/*
******************************************************************************
* Copyright (C) 2003-2014, International Business Machines Corporation and
* others. All Rights Reserved.
******************************************************************************
*/

package com.ibm.icu.util;

import java.io.Serializable;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.AccessControlException;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.ParseException;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Map.Entry;
import java.util.MissingResourceException;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;

import com.ibm.icu.impl.ICUCache;
import com.ibm.icu.impl.ICUResourceBundle;
import com.ibm.icu.impl.ICUResourceTableAccess;
import com.ibm.icu.impl.LocaleIDParser;
import com.ibm.icu.impl.LocaleIDs;
import com.ibm.icu.impl.LocaleUtility;
import com.ibm.icu.impl.SimpleCache;
import com.ibm.icu.impl.locale.AsciiUtil;
import com.ibm.icu.impl.locale.BaseLocale;
import com.ibm.icu.impl.locale.Extension;
import com.ibm.icu.impl.locale.InternalLocaleBuilder;
import com.ibm.icu.impl.locale.KeyTypeData;
import com.ibm.icu.impl.locale.LanguageTag;
import com.ibm.icu.impl.locale.LocaleExtensions;
import com.ibm.icu.impl.locale.LocaleSyntaxException;
import com.ibm.icu.impl.locale.ParseStatus;
import com.ibm.icu.impl.locale.UnicodeLocaleExtension;
import com.ibm.icu.lang.UScript;
import com.ibm.icu.text.LocaleDisplayNames;
import com.ibm.icu.text.LocaleDisplayNames.DialectHandling;

/**
 * {@icuenhanced java.util.Locale}.{@icu _usage_}
 *
 * A class analogous to {@link java.util.Locale} that provides additional
 * support for ICU protocol.  In ICU 3.0 this class is enhanced to support
 * RFC 3066 language identifiers.
 *
 * <p>Many classes and services in ICU follow a factory idiom, in
 * which a factory method or object responds to a client request with
 * an object.  The request includes a locale (the <i>requested</i>
 * locale), and the returned object is constructed using data for that
 * locale.  The system may lack data for the requested locale, in
 * which case the locale fallback mechanism will be invoked until a
 * populated locale is found (the <i>valid</i> locale).  Furthermore,
 * even when a populated locale is found (the <i>valid</i> locale),
 * further fallback may be required to reach a locale containing the
 * specific data required by the service (the <i>actual</i> locale).
 *
 * <p>ULocale performs <b>'normalization'</b> and <b>'canonicalization'</b> of locale ids.
 * Normalization 'cleans up' ICU locale ids as follows:
 * <ul>
 * <li>language, script, country, variant, and keywords are properly cased<br>
 * (lower, title, upper, upper, and lower case respectively)</li>
 * <li>hyphens used as separators are converted to underscores</li>
 * <li>three-letter language and country ids are converted to two-letter
 * equivalents where available</li>
 * <li>surrounding spaces are removed from keywords and values</li>
 * <li>if there are multiple keywords, they are put in sorted order</li>
 * </ul>
 * Canonicalization additionally performs the following:
 * <ul>
 * <li>POSIX ids are converted to ICU format IDs</li>
 * <li>'grandfathered' 3066 ids are converted to ICU standard form</li>
 * <li>'PREEURO' and 'EURO' variants are converted to currency keyword form,
 * with the currency
 * id appropriate to the country of the locale (for PREEURO) or EUR (for EURO).
 * </ul>
 * All ULocale constructors automatically normalize the locale id.  To handle
 * POSIX ids, <code>canonicalize</code> can be called to convert the id
 * to canonical form, or the <code>canonicalInstance</code> factory method
 * can be called.</p>
 *
 * <p>This class provides selectors {@link #VALID_LOCALE} and {@link
 * #ACTUAL_LOCALE} intended for use in methods named
 * <tt>getLocale()</tt>.  These methods exist in several ICU classes,
 * including {@link com.ibm.icu.util.Calendar}, {@link
 * com.ibm.icu.util.Currency}, {@link com.ibm.icu.text.UFormat},
 * {@link com.ibm.icu.text.BreakIterator},
 * <a href="../text/Collator.html" title="class in com.ibm.icu.text"><code>Collator</code></a>,
 * {@link com.ibm.icu.text.DateFormatSymbols}, and {@link
 * com.ibm.icu.text.DecimalFormatSymbols} and their subclasses, if
 * any.  Once an object of one of these classes has been created,
 * <tt>getLocale()</tt> may be called on it to determine the valid and
 * actual locale arrived at during the object's construction.
 *
 * <p>Note: The <i>actual</i> locale is returned correctly, but the <i>valid</i>
 * locale is not, in most cases.
 *
 * @see java.util.Locale
 * @author weiv
 * @author Alan Liu
 * @author Ram Viswanadha
 * @stable ICU 2.8
 */
public final class ULocale implements Serializable, Comparable<ULocale> {
    // using serialver from jdk1.4.2_05
    private static final long serialVersionUID = 3715177670352309217L;

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale ENGLISH = new ULocale("en", Locale.ENGLISH);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale FRENCH = new ULocale("fr", Locale.FRENCH);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale GERMAN = new ULocale("de", Locale.GERMAN);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale ITALIAN = new ULocale("it", Locale.ITALIAN);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale JAPANESE = new ULocale("ja", Locale.JAPANESE);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale KOREAN = new ULocale("ko", Locale.KOREAN);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale CHINESE = new ULocale("zh", Locale.CHINESE);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale SIMPLIFIED_CHINESE = new ULocale("zh_Hans", Locale.CHINESE);

    /**
     * Useful constant for language.
     * @stable ICU 3.0
     */
    public static final ULocale TRADITIONAL_CHINESE = new ULocale("zh_Hant", Locale.CHINESE);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale FRANCE = new ULocale("fr_FR", Locale.FRANCE);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale GERMANY = new ULocale("de_DE", Locale.GERMANY);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale ITALY = new ULocale("it_IT", Locale.ITALY);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale JAPAN = new ULocale("ja_JP", Locale.JAPAN);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale KOREA = new ULocale("ko_KR", Locale.KOREA);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale CHINA = new ULocale("zh_Hans_CN", Locale.CHINA);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale PRC = CHINA;

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale TAIWAN = new ULocale("zh_Hant_TW", Locale.TAIWAN);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale UK = new ULocale("en_GB", Locale.UK);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale US = new ULocale("en_US", Locale.US);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale CANADA = new ULocale("en_CA", Locale.CANADA);

    /**
     * Useful constant for country/region.
     * @stable ICU 3.0
     */
    public static final ULocale CANADA_FRENCH = new ULocale("fr_CA", Locale.CANADA_FRENCH);

    /**
     * Handy constant.
     */
    private static final String EMPTY_STRING = "";

    // Used in both ULocale and LocaleIDParser, so moved up here.
    private static final char UNDERSCORE            = '_';

    // default empty locale
    private static final Locale EMPTY_LOCALE = new Locale("", "");

    // special keyword key for Unicode locale attributes
    private static final String LOCALE_ATTRIBUTE_KEY = "attribute";

    /**
     * The root ULocale.
     * @stable ICU 2.8
     */
    public static final ULocale ROOT = new ULocale("", EMPTY_LOCALE);

    /**
     * Enum for locale categories. These locale categories are used to get/set the default locale for
     * the specific functionality represented by the category.
     * @stable ICU 49
     */
    public enum Category {
        /**
         * Category used to represent the default locale for displaying user interfaces.
         * @stable ICU 49
         */
        DISPLAY,
        /**
         * Category used to represent the default locale for formatting date, number and/or currency.
         * @stable ICU 49
         */
        FORMAT
    }

    private static final SimpleCache<Locale, ULocale> CACHE = new SimpleCache<Locale, ULocale>();

    /**
     * Cache the locale.
     */
    private transient volatile Locale locale;

    /**
     * The raw localeID that we were passed in.
     */
    private String localeID;

    /**
     * Cache the locale data container fields.
     * In future, we want to use them as the primary locale identifier storage.
     */
    private transient volatile BaseLocale baseLocale;
    private transient volatile LocaleExtensions extensions;


    private static String[][] CANONICALIZE_MAP;
    private static String[][] variantsToKeywords;

    private static void initCANONICALIZE_MAP() {
        if (CANONICALIZE_MAP == null) {
            /**
             * This table lists pairs of locale ids for canonicalization.  The
             * The 1st item is the normalized id. The 2nd item is the
             * canonicalized id. The 3rd is the keyword. The 4th is the keyword value.
             */
            String[][] tempCANONICALIZE_MAP = {
//              { EMPTY_STRING,     "en_US_POSIX", null, null }, /* .NET name */
                { "C",              "en_US_POSIX", null, null }, /* POSIX name */
                { "art_LOJBAN",     "jbo", null, null }, /* registered name */
                { "az_AZ_CYRL",     "az_Cyrl_AZ", null, null }, /* .NET name */
                { "az_AZ_LATN",     "az_Latn_AZ", null, null }, /* .NET name */
                { "ca_ES_PREEURO",  "ca_ES", "currency", "ESP" },
                { "cel_GAULISH",    "cel__GAULISH", null, null }, /* registered name */
                { "de_1901",        "de__1901", null, null }, /* registered name */
                { "de_1906",        "de__1906", null, null }, /* registered name */
                { "de__PHONEBOOK",  "de", "collation", "phonebook" }, /* Old ICU name */
                { "de_AT_PREEURO",  "de_AT", "currency", "ATS" },
                { "de_DE_PREEURO",  "de_DE", "currency", "DEM" },
                { "de_LU_PREEURO",  "de_LU", "currency", "EUR" },
                { "el_GR_PREEURO",  "el_GR", "currency", "GRD" },
                { "en_BOONT",       "en__BOONT", null, null }, /* registered name */
                { "en_SCOUSE",      "en__SCOUSE", null, null }, /* registered name */
                { "en_BE_PREEURO",  "en_BE", "currency", "BEF" },
                { "en_IE_PREEURO",  "en_IE", "currency", "IEP" },
                { "es__TRADITIONAL", "es", "collation", "traditional" }, /* Old ICU name */
                { "es_ES_PREEURO",  "es_ES", "currency", "ESP" },
                { "eu_ES_PREEURO",  "eu_ES", "currency", "ESP" },
                { "fi_FI_PREEURO",  "fi_FI", "currency", "FIM" },
                { "fr_BE_PREEURO",  "fr_BE", "currency", "BEF" },
                { "fr_FR_PREEURO",  "fr_FR", "currency", "FRF" },
                { "fr_LU_PREEURO",  "fr_LU", "currency", "LUF" },
                { "ga_IE_PREEURO",  "ga_IE", "currency", "IEP" },
                { "gl_ES_PREEURO",  "gl_ES", "currency", "ESP" },
                { "hi__DIRECT",     "hi", "collation", "direct" }, /* Old ICU name */
                { "it_IT_PREEURO",  "it_IT", "currency", "ITL" },
                { "ja_JP_TRADITIONAL", "ja_JP", "calendar", "japanese" },
//              { "nb_NO_NY",       "nn_NO", null, null },
                { "nl_BE_PREEURO",  "nl_BE", "currency", "BEF" },
                { "nl_NL_PREEURO",  "nl_NL", "currency", "NLG" },
                { "pt_PT_PREEURO",  "pt_PT", "currency", "PTE" },
                { "sl_ROZAJ",       "sl__ROZAJ", null, null }, /* registered name */
                { "sr_SP_CYRL",     "sr_Cyrl_RS", null, null }, /* .NET name */
                { "sr_SP_LATN",     "sr_Latn_RS", null, null }, /* .NET name */
                { "sr_YU_CYRILLIC", "sr_Cyrl_RS", null, null }, /* Linux name */
                { "th_TH_TRADITIONAL", "th_TH", "calendar", "buddhist" }, /* Old ICU name */
                { "uz_UZ_CYRILLIC", "uz_Cyrl_UZ", null, null }, /* Linux name */
                { "uz_UZ_CYRL",     "uz_Cyrl_UZ", null, null }, /* .NET name */
                { "uz_UZ_LATN",     "uz_Latn_UZ", null, null }, /* .NET name */
                { "zh_CHS",         "zh_Hans", null, null }, /* .NET name */
                { "zh_CHT",         "zh_Hant", null, null }, /* .NET name */
                { "zh_GAN",         "zh__GAN", null, null }, /* registered name */
                { "zh_GUOYU",       "zh", null, null }, /* registered name */
                { "zh_HAKKA",       "zh__HAKKA", null, null }, /* registered name */
                { "zh_MIN",         "zh__MIN", null, null }, /* registered name */
                { "zh_MIN_NAN",     "zh__MINNAN", null, null }, /* registered name */
                { "zh_WUU",         "zh__WUU", null, null }, /* registered name */
                { "zh_XIANG",       "zh__XIANG", null, null }, /* registered name */
                { "zh_YUE",         "zh__YUE", null, null } /* registered name */
            };

            synchronized (ULocale.class) {
                if (CANONICALIZE_MAP == null) {
                    CANONICALIZE_MAP = tempCANONICALIZE_MAP;
                }
            }
        }
        if (variantsToKeywords == null) {
            /**
             * This table lists pairs of locale ids for canonicalization.  The
             * The first item is the normalized variant id.
             */
            String[][] tempVariantsToKeywords = {
                    { "EURO",   "currency", "EUR" },
                    { "PINYIN", "collation", "pinyin" }, /* Solaris variant */
                    { "STROKE", "collation", "stroke" }  /* Solaris variant */
            };

            synchronized (ULocale.class) {
                if (variantsToKeywords == null) {
                    variantsToKeywords = tempVariantsToKeywords;
                }
            }
        }
    }

    /**
     * Private constructor used by static initializers.
     */
    private ULocale(String localeID, Locale locale) {
        this.localeID = localeID;
        this.locale = locale;
    }

    /**
     * Construct a ULocale object from a {@link java.util.Locale}.
     * @param loc a JDK locale
     */
    private ULocale(Locale loc) {
        this.localeID = getName(forLocale(loc).toString());
        this.locale = loc;
    }

    /**
     * {@icu} Returns a ULocale object for a {@link java.util.Locale}.
     * The ULocale is canonicalized.
     * @param loc a JDK locale
     * @stable ICU 3.2
     */
    public static ULocale forLocale(Locale loc) {
        if (loc == null) {
            return null;
        }
        ULocale result = CACHE.get(loc);
        if (result == null) {
            result = JDKLocaleHelper.toULocale(loc);
            CACHE.put(loc, result);
        }
        return result;
    }

    /**
     * {@icu} Constructs a ULocale from a RFC 3066 locale ID. The locale ID consists
     * of optional language, script, country, and variant fields in that order,
     * separated by underscores, followed by an optional keyword list.  The
     * script, if present, is four characters long-- this distinguishes it
     * from a country code, which is two characters long.  Other fields
     * are distinguished by position as indicated by the underscores.  The
     * start of the keyword list is indicated by '@', and consists of two
     * or more keyword/value pairs separated by semicolons(';').
     * 
     * <p>This constructor does not canonicalize the localeID.  So, for
     * example, "zh__pinyin" remains unchanged instead of converting
     * to "zh@collation=pinyin".  By default ICU only recognizes the
     * latter as specifying pinyin collation.  Use {@link #createCanonical}
     * or {@link #canonicalize} if you need to canonicalize the localeID.
     *
     * @param localeID string representation of the locale, e.g:
     * "en_US", "sy_Cyrl_YU", "zh__pinyin", "es_ES@currency=EUR;collation=traditional"
     * @stable ICU 2.8
     */
    public ULocale(String localeID) {
        this.localeID = getName(localeID);
    }

    /**
     * Convenience overload of ULocale(String, String, String) for
     * compatibility with java.util.Locale.
     * @see #ULocale(String, String, String)
     * @stable ICU 3.4
     */
    public ULocale(String a, String b) {
        this(a, b, null);
    }

    /**
     * Constructs a ULocale from a localeID constructed from the three 'fields' a, b, and
     * c.  These fields are concatenated using underscores to form a localeID of the form
     * a_b_c, which is then handled like the localeID passed to <code>ULocale(String
     * localeID)</code>.
     *
     * <p>Java locale strings consisting of language, country, and
     * variant will be handled by this form, since the country code
     * (being shorter than four letters long) will not be interpreted
     * as a script code.  If a script code is present, the final
     * argument ('c') will be interpreted as the country code.  It is
     * recommended that this constructor only be used to ease porting,
     * and that clients instead use the single-argument constructor
     * when constructing a ULocale from a localeID.
     * @param a first component of the locale id
     * @param b second component of the locale id
     * @param c third component of the locale id
     * @see #ULocale(String)
     * @stable ICU 3.0
     */
    public ULocale(String a, String b, String c) {
        localeID = getName(lscvToID(a, b, c, EMPTY_STRING));
    }

    /**
     * {@icu} Creates a ULocale from the id by first canonicalizing the id.
     * @param nonCanonicalID the locale id to canonicalize
     * @return the locale created from the canonical version of the ID.
     * @stable ICU 3.0
     */
    public static ULocale createCanonical(String nonCanonicalID) {
        return new ULocale(canonicalize(nonCanonicalID), (Locale)null);
    }

    private static String lscvToID(String lang, String script, String country, String variant) {
        StringBuilder buf = new StringBuilder();

        if (lang != null && lang.length() > 0) {
            buf.append(lang);
        }
        if (script != null && script.length() > 0) {
            buf.append(UNDERSCORE);
            buf.append(script);
        }
        if (country != null && country.length() > 0) {
            buf.append(UNDERSCORE);
            buf.append(country);
        }
        if (variant != null && variant.length() > 0) {
            if (country == null || country.length() == 0) {
                buf.append(UNDERSCORE);
            }
            buf.append(UNDERSCORE);
            buf.append(variant);
        }
        return buf.toString();
    }

    /**
     * {@icu} Converts this ULocale object to a {@link java.util.Locale}.
     * @return a JDK locale that either exactly represents this object
     * or is the closest approximation.
     * @stable ICU 2.8
     */
    public Locale toLocale() {
        if (locale == null) {
            locale = JDKLocaleHelper.toLocale(this);
        }
        return locale;
    }

    private static ICUCache<String, String> nameCache = new SimpleCache<String, String>();

    /**
     * Keep our own default ULocale.
     */
    private static Locale defaultLocale = Locale.getDefault();
    private static ULocale defaultULocale;

    private static Locale[] defaultCategoryLocales = new Locale[Category.values().length];
    private static ULocale[] defaultCategoryULocales = new ULocale[Category.values().length];

    static {
        defaultULocale = forLocale(defaultLocale);

        // For Java 6 or older JRE, ICU initializes the default script from
        // "user.script" system property. The system property was added
        // in Java 7. On JRE 7, Locale.getDefault() should reflect the
        // property value to the Locale's default. So ICU just relies on
        // Locale.getDefault().
        
        // Note: The "user.script" property is only used by initialization.
        // 
        if (JDKLocaleHelper.isJava7orNewer()) {
            for (Category cat: Category.values()) {
                int idx = cat.ordinal();
                defaultCategoryLocales[idx] = JDKLocaleHelper.getDefault(cat);
                defaultCategoryULocales[idx] = forLocale(defaultCategoryLocales[idx]);
            }
        } else {
            // Make sure the current default Locale is original.
            // If not, it means that someone updated the default Locale.
            // In this case, user.XXX properties are already out of date
            // and we should not use user.script.
            if (JDKLocaleHelper.isOriginalDefaultLocale(defaultLocale)) {
                // Use "user.script" if available
                String userScript = JDKLocaleHelper.getSystemProperty("user.script");
                if (userScript != null && LanguageTag.isScript(userScript)) {
                    // Note: Builder or forLanguageTag cannot be used here
                    // when one of Locale fields is not well-formed.
                    BaseLocale base = defaultULocale.base();
                    BaseLocale newBase = BaseLocale.getInstance(base.getLanguage(), userScript,
                            base.getRegion(), base.getVariant());
                    defaultULocale = getInstance(newBase, defaultULocale.extensions());
                }
            }

            // Java 6 or older does not have separated category locales,
            // use the non-category default for all
            for (Category cat: Category.values()) {
                int idx = cat.ordinal();
                defaultCategoryLocales[idx] = defaultLocale;
                defaultCategoryULocales[idx] = defaultULocale;
            }
        }
    }

    /**
     * Returns the current default ULocale.
     * <p>
     * The default ULocale is synchronized to the default Java Locale. This method checks
     * the current default Java Locale and returns an equivalent ULocale.
     * <p>
     * <b>Note:</b> Before Java 7, the JDK Locale was not able to represent a locale's script.
     * Therefore, the script field in the default ULocale is always empty unless
     * a ULocale with non-empty script is explicitly set by {@link #setDefault(ULocale)}
     * on Java 6 or older systems.
     * <p>
     * <b>Note for ICU 49 or later:</b> Some JRE implementations allow users to override the default
     * JDK Locale using system properties - <code>user.language</code>, <code>user.country</code>
     * and <code>user.variant</code>. In addition to these system properties, some Java 7
     * implementations support <code>user.script</code> for overriding the default Locale's script.
     * ICU 49 and later versions use the <code>user.script</code> system property on Java 6
     * or older systems supporting other <code>user.*</code> system properties to initialize
     * the default ULocale. The <code>user.script</code> override for default ULocale is not
     * used on Java 7, or if the current Java default Locale is changed after start up.
     * 
     * @return the default ULocale.
     * @stable ICU 2.8
     */
    public static ULocale getDefault() {
        synchronized (ULocale.class) {
            if (defaultULocale == null) {
                // When Java's default locale has extensions (such as ja-JP-u-ca-japanese),
                // Locale -> ULocale mapping requires BCP47 keyword mapping data that is currently
                // stored in a resource bundle. However, UResourceBundle currently requires
                // non-null default ULocale. For now, this implementation returns ULocale.ROOT
                // to avoid the problem.

                // TODO: Consider moving BCP47 mapping data out of resource bundle later.

                return ULocale.ROOT;
            }
            Locale currentDefault = Locale.getDefault();
            if (!defaultLocale.equals(currentDefault)) {
                defaultLocale = currentDefault;
                defaultULocale = forLocale(currentDefault);

                if (!JDKLocaleHelper.isJava7orNewer()) {
                    // Detected Java default Locale change.
                    // We need to update category defaults to match the
                    // Java 7's behavior on Java 6 or older environment.
                    for (Category cat : Category.values()) {
                        int idx = cat.ordinal();
                        defaultCategoryLocales[idx] = currentDefault;
                        defaultCategoryULocales[idx] = forLocale(currentDefault);
                    }
                }
            }
            return defaultULocale;
        }
    }

    /**
     * Sets the default ULocale.  This also sets the default Locale.
     * If the caller does not have write permission to the
     * user.language property, a security exception will be thrown,
     * and the default ULocale will remain unchanged.
     * <p>
     * By setting the default ULocale with this method, all of the default categoy locales
     * are also set to the specified default ULocale.
     * @param newLocale the new default locale
     * @throws SecurityException if a security manager exists and its
     *        <code>checkPermission</code> method doesn't allow the operation.
     * @throws NullPointerException if <code>newLocale</code> is null
     * @see SecurityManager#checkPermission(java.security.Permission)
     * @see java.util.PropertyPermission
     * @see ULocale#setDefault(Category, ULocale)
     * @stable ICU 3.0
     */
    public static synchronized void setDefault(ULocale newLocale){
        defaultLocale = newLocale.toLocale();
        Locale.setDefault(defaultLocale);
        defaultULocale = newLocale;
        // This method also updates all category default locales
        for (Category cat : Category.values()) {
            setDefault(cat, newLocale);
        }
    }

    /**
     * Returns the current default ULocale for the specified category.
     * 
     * @param category the category
     * @return the default ULocale for the specified category.
     * @stable ICU 49
     */
    public static ULocale getDefault(Category category) {
        synchronized (ULocale.class) {
            int idx = category.ordinal();
            if (defaultCategoryULocales[idx] == null) {
                // Just in case this method is called during ULocale class
                // initialization. Unlike getDefault(), we do not have
                // cyclic dependency for category default.
                return ULocale.ROOT;
            }
            if (JDKLocaleHelper.isJava7orNewer()) {
                Locale currentCategoryDefault = JDKLocaleHelper.getDefault(category);
                if (!defaultCategoryLocales[idx].equals(currentCategoryDefault)) {
                    defaultCategoryLocales[idx] = currentCategoryDefault;
                    defaultCategoryULocales[idx] = forLocale(currentCategoryDefault);
                }
            } else {
                // java.util.Locale.setDefault(Locale) in Java 7 updates
                // category locale defaults. On Java 6 or older environment,
                // ICU4J checks if the default locale has changed and update
                // category ULocales here if necessary.
                
                // Note: When java.util.Locale.setDefault(Locale) is called
                // with a Locale same with the previous one, Java 7 still
                // updates category locale defaults. On Java 6 or older env,
                // there is no good way to detect the event, ICU4J simply
                // check if the default Java Locale has changed since last
                // time.

                Locale currentDefault = Locale.getDefault();
                if (!defaultLocale.equals(currentDefault)) {
                    defaultLocale = currentDefault;
                    defaultULocale = forLocale(currentDefault);

                    for (Category cat : Category.values()) {
                        int tmpIdx = cat.ordinal();
                        defaultCategoryLocales[tmpIdx] = currentDefault;
                        defaultCategoryULocales[tmpIdx] = forLocale(currentDefault);
                    }
                }
                
                // No synchronization with JDK Locale, because category default
                // is not supported in Java 6 or older versions
            }
            return defaultCategoryULocales[idx];
        }
    }

    /**
     * Sets the default <code>ULocale</code> for the specified <code>Category</code>.
     * This also sets the default <code>Locale</code> for the specified <code>Category</code>
     * of the JVM. If the caller does not have write permission to the
     * user.language property, a security exception will be thrown,
     * and the default ULocale for the specified Category will remain unchanged.
     * 
     * @param category the specified category to set the default locale
     * @param newLocale the new default locale
     * @see SecurityManager#checkPermission(java.security.Permission)
     * @see java.util.PropertyPermission
     * @stable ICU 49
     */
    public static synchronized void setDefault(Category category, ULocale newLocale) {
        Locale newJavaDefault = newLocale.toLocale();
        int idx = category.ordinal();
        defaultCategoryULocales[idx] = newLocale;
        defaultCategoryLocales[idx] = newJavaDefault;
        JDKLocaleHelper.setDefault(category, newJavaDefault);
    }

    /**
     * This is for compatibility with Locale-- in actuality, since ULocale is
     * immutable, there is no reason to clone it, so this API returns 'this'.
     * @stable ICU 3.0
     */
    public Object clone() {
        return this;
    }

    /**
     * Returns the hashCode.
     * @stable ICU 3.0
     */
    public int hashCode() {
        return localeID.hashCode();
    }

    /**
     * Returns true if the other object is another ULocale with the
     * same full name.
     * Note that since names are not canonicalized, two ULocales that
     * function identically might not compare equal.
     *
     * @return true if this Locale is equal to the specified object.
     * @stable ICU 3.0
     */
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof ULocale) {
            return localeID.equals(((ULocale)obj).localeID);
        }
        return false;
    }

    /**
     * Compares two ULocale for ordering.
     * <p><b>Note:</b> The order might change in future.</p>
     * 
     * @param other the ULocale to be compared.
     * @return a negative integer, zero, or a positive integer as this ULocale is less than, equal to, or greater
     * than the specified ULocale.
     * @throws NullPointerException if <code>other</code> is null.
     * 
     * @draft ICU 53
     * @provisional This API might change or be removed in a future release.
     */
    public int compareTo(ULocale other) {
        if (this == other) {
            return 0;
        }

        int cmp = 0;

        // Language
        cmp = getLanguage().compareTo(other.getLanguage());
        if (cmp == 0) {
            // Script
            cmp = getScript().compareTo(other.getScript());
            if (cmp == 0) {
                // Region
                cmp = getCountry().compareTo(other.getCountry());
                if (cmp == 0) {
                    // Variant
                    cmp = getVariant().compareTo(other.getVariant());
                    if (cmp == 0) {
                        // Keywords
                        Iterator<String> thisKwdItr = getKeywords();
                        Iterator<String> otherKwdItr = other.getKeywords();

                        if (thisKwdItr == null) {
                            cmp = otherKwdItr == null ? 0 : -1;
                        } else if (otherKwdItr == null) {
                            cmp = 1;
                        } else {
                            // Both have keywords
                            while (cmp == 0 && thisKwdItr.hasNext()) {
                                if (!otherKwdItr.hasNext()) {
                                    cmp = 1;
                                    break;
                                }
                                // Compare keyword keys
                                String thisKey = thisKwdItr.next();
                                String otherKey = otherKwdItr.next();
                                cmp = thisKey.compareTo(otherKey);
                                if (cmp == 0) {
                                    // Compare keyword values
                                    String thisVal = getKeywordValue(thisKey);
                                    String otherVal = other.getKeywordValue(otherKey);
                                    if (thisVal == null) {
                                        cmp = otherVal == null ? 0 : -1;
                                    } else if (otherVal == null) {
                                        cmp = 1;
                                    } else {
                                        cmp = thisVal.compareTo(otherVal);
                                    }
                                }
                            }
                            if (cmp == 0 && otherKwdItr.hasNext()) {
                                cmp = -1;
                            }
                        }
                    }
                }
            }
        }

        // Normalize the result value:
        // Note: String.compareTo() may return value other than -1, 0, 1.
        // A value other than those are OK by the definition, but we don't want
        // associate any semantics other than negative/zero/positive.
        return (cmp < 0) ? -1 : ((cmp > 0) ? 1 : 0);
    }

    /**
     * {@icunote} Unlike the Locale API, this returns an array of <code>ULocale</code>,
     * not <code>Locale</code>.  Returns a list of all installed locales.
     * @stable ICU 3.0
     */
    public static ULocale[] getAvailableLocales() {
        return ICUResourceBundle.getAvailableULocales();
    }

    /**
     * Returns a list of all 2-letter country codes defined in ISO 3166.
     * Can be used to create Locales.
     * @stable ICU 3.0
     */
    public static String[] getISOCountries() {
        return LocaleIDs.getISOCountries();
    }

    /**
     * Returns a list of all 2-letter language codes defined in ISO 639.
     * Can be used to create Locales.
     * [NOTE:  ISO 639 is not a stable standard-- some languages' codes have changed.
     * The list this function returns includes both the new and the old codes for the
     * languages whose codes have changed.]
     * @stable ICU 3.0
     */
    public static String[] getISOLanguages() {
        return LocaleIDs.getISOLanguages();
    }

    /**
     * Returns the language code for this locale, which will either be the empty string
     * or a lowercase ISO 639 code.
     * @see #getDisplayLanguage()
     * @see #getDisplayLanguage(ULocale)
     * @stable ICU 3.0
     */
    public String getLanguage() {
        return base().getLanguage();
    }

    /**
     * Returns the language code for the locale ID,
     * which will either be the empty string
     * or a lowercase ISO 639 code.
     * @see #getDisplayLanguage()
     * @see #getDisplayLanguage(ULocale)
     * @stable ICU 3.0
     */
    public static String getLanguage(String localeID) {
        return new LocaleIDParser(localeID).getLanguage();
    }

    /**
     * Returns the script code for this locale, which might be the empty string.
     * @see #getDisplayScript()
     * @see #getDisplayScript(ULocale)
     * @stable ICU 3.0
     */
    public String getScript() {
        return base().getScript();
    }

    /**
     * {@icu} Returns the script code for the specified locale, which might be the empty
     * string.
     * @see #getDisplayScript()
     * @see #getDisplayScript(ULocale)
     * @stable ICU 3.0
     */
    public static String getScript(String localeID) {
        return new LocaleIDParser(localeID).getScript();
    }

    /**
     * Returns the country/region code for this locale, which will either be the empty string
     * or an uppercase ISO 3166 2-letter code.
     * @see #getDisplayCountry()
     * @see #getDisplayCountry(ULocale)
     * @stable ICU 3.0
     */
    public String getCountry() {
        return base().getRegion();
    }

    /**
     * {@icu} Returns the country/region code for this locale, which will either be the empty string
     * or an uppercase ISO 3166 2-letter code.
     * @param localeID The locale identification string.
     * @see #getDisplayCountry()
     * @see #getDisplayCountry(ULocale)
     * @stable ICU 3.0
     */
    public static String getCountry(String localeID) {
        return new LocaleIDParser(localeID).getCountry();
    }

    /**
     * Returns the variant code for this locale, which might be the empty string.
     * @see #getDisplayVariant()
     * @see #getDisplayVariant(ULocale)
     * @stable ICU 3.0
     */
    public String getVariant() {
        return base().getVariant();
    }

    /**
     * {@icu} Returns the variant code for the specified locale, which might be the empty string.
     * @see #getDisplayVariant()
     * @see #getDisplayVariant(ULocale)
     * @stable ICU 3.0
     */
    public static String getVariant(String localeID) {
        return new LocaleIDParser(localeID).getVariant();
    }

    /**
     * {@icu} Returns the fallback locale for the specified locale, which might be the
     * empty string.
     * @stable ICU 3.2
     */
    public static String getFallback(String localeID) {
        return getFallbackString(getName(localeID));
    }

    /**
     * {@icu} Returns the fallback locale for this locale.  If this locale is root,
     * returns null.
     * @stable ICU 3.2
     */
    public ULocale getFallback() {
        if (localeID.length() == 0 || localeID.charAt(0) == '@') {
            return null;
        }
        return new ULocale(getFallbackString(localeID), (Locale)null);
    }

    /**
     * Returns the given (canonical) locale id minus the last part before the tags.
     */
    private static String getFallbackString(String fallback) {
        int extStart = fallback.indexOf('@');
        if (extStart == -1) {
            extStart = fallback.length();
        }
        int last = fallback.lastIndexOf('_', extStart);
        if (last == -1) {
            last = 0;
        } else {
            // truncate empty segment
            while (last > 0) {
                if (fallback.charAt(last - 1) != '_') {
                    break;
                }
                last--;
            }
        }
        return fallback.substring(0, last) + fallback.substring(extStart);
    }

    /**
     * {@icu} Returns the (normalized) base name for this locale,
     * like {@link #getName()}, but without keywords.
     *
     * @return the base name as a String.
     * @stable ICU 3.0
     */
    public String getBaseName() {
        return getBaseName(localeID);
    }

    /**
     * {@icu} Returns the (normalized) base name for the specified locale,
     * like {@link #getName(String)}, but without keywords.
     *
     * @param localeID the locale ID as a string
     * @return the base name as a String.
     * @stable ICU 3.0
     */
    public static String getBaseName(String localeID){
        if (localeID.indexOf('@') == -1) {
            return localeID;
        }
        return new LocaleIDParser(localeID).getBaseName();
    }

    /**
     * {@icu} Returns the (normalized) full name for this locale.
     *
     * @return String the full name of the localeID
     * @stable ICU 3.0
     */
    public String getName() {
        return localeID; // always normalized
    }
    
    /**
     * Gets the shortest length subtag's size.
     *
     * @param localeID
     * @return The size of the shortest length subtag
     **/
    private static int getShortestSubtagLength(String localeID) {
        int localeIDLength = localeID.length();
        int length = localeIDLength;
        boolean reset = true;
        int tmpLength = 0;
        
        for (int i = 0; i < localeIDLength; i++) {
            if (localeID.charAt(i) != '_' && localeID.charAt(i) != '-') {
                if (reset) {
                    reset = false;
                    tmpLength = 0;
                }
                tmpLength++;
            } else {
                if (tmpLength != 0 && tmpLength < length) {
                    length = tmpLength;
                }
                reset = true;
            }
        }
        
        return length;
    }

    /**
     * {@icu} Returns the (normalized) full name for the specified locale.
     *
     * @param localeID the localeID as a string
     * @return String the full name of the localeID
     * @stable ICU 3.0
     */
    public static String getName(String localeID){
        String tmpLocaleID;
        // Convert BCP47 id if necessary
        if (localeID != null && !localeID.contains("@") && getShortestSubtagLength(localeID) == 1) {
            tmpLocaleID = forLanguageTag(localeID).getName();
            if (tmpLocaleID.length() == 0) {
                tmpLocaleID = localeID;
            }
        } else {
            tmpLocaleID = localeID;
        }
        String name = nameCache.get(tmpLocaleID);
        if (name == null) {
            name = new LocaleIDParser(tmpLocaleID).getName();
            nameCache.put(tmpLocaleID, name);
        }
        return name;
    }

    /**
     * Returns a string representation of this object.
     * @stable ICU 3.0
     */
    public String toString() {
        return localeID;
    }

    /**
     * {@icu} Returns an iterator over keywords for this locale.  If there
     * are no keywords, returns null.
     * @return iterator over keywords, or null if there are no keywords.
     * @stable ICU 3.0
     */
    public Iterator<String> getKeywords() {
        return getKeywords(localeID);
    }

    /**
     * {@icu} Returns an iterator over keywords for the specified locale.  If there
     * are no keywords, returns null.
     * @return an iterator over the keywords in the specified locale, or null
     * if there are no keywords.
     * @stable ICU 3.0
     */
    public static Iterator<String> getKeywords(String localeID){
        return new LocaleIDParser(localeID).getKeywords();
    }

    /**
     * {@icu} Returns the value for a keyword in this locale. If the keyword is not
     * defined, returns null.
     * @param keywordName name of the keyword whose value is desired. Case insensitive.
     * @return the value of the keyword, or null.
     * @stable ICU 3.0
     */
    public String getKeywordValue(String keywordName){
        return getKeywordValue(localeID, keywordName);
    }

    /**
     * {@icu} Returns the value for a keyword in the specified locale. If the keyword is
     * not defined, returns null.  The locale name does not need to be normalized.
     * @param keywordName name of the keyword whose value is desired. Case insensitive.
     * @return String the value of the keyword as a string
     * @stable ICU 3.0
     */
    public static String getKeywordValue(String localeID, String keywordName) {
        return new LocaleIDParser(localeID).getKeywordValue(keywordName);
    }

    /**
     * {@icu} Returns the canonical name for the specified locale ID.  This is used to
     * convert POSIX and other grandfathered IDs to standard ICU form.
     * @param localeID the locale id
     * @return the canonicalized id
     * @stable ICU 3.0
     */
    public static String canonicalize(String localeID){
        LocaleIDParser parser = new LocaleIDParser(localeID, true);
        String baseName = parser.getBaseName();
        boolean foundVariant = false;

        // formerly, we always set to en_US_POSIX if the basename was empty, but
        // now we require that the entire id be empty, so that "@foo=bar"
        // will pass through unchanged.
        // {dlf} I'd rather keep "" unchanged.
        if (localeID.equals("")) {
            return "";
//              return "en_US_POSIX";
        }

        // we have an ID in the form xx_Yyyy_ZZ_KKKKK

        initCANONICALIZE_MAP();

        /* convert the variants to appropriate ID */
        for (int i = 0; i < variantsToKeywords.length; i++) {
            String[] vals = variantsToKeywords[i];
            int idx = baseName.lastIndexOf("_" + vals[0]);
            if (idx > -1) {
                foundVariant = true;

                baseName = baseName.substring(0, idx);
                if (baseName.endsWith("_")) {
                    baseName = baseName.substring(0, --idx);
                }
                parser.setBaseName(baseName);
                parser.defaultKeywordValue(vals[1], vals[2]);
                break;
            }
        }

        /* See if this is an already known locale */
        for (int i = 0; i < CANONICALIZE_MAP.length; i++) {
            if (CANONICALIZE_MAP[i][0].equals(baseName)) {
                foundVariant = true;

                String[] vals = CANONICALIZE_MAP[i];
                parser.setBaseName(vals[1]);
                if (vals[2] != null) {
                    parser.defaultKeywordValue(vals[2], vals[3]);
                }
                break;
            }
        }

        /* total mondo hack for Norwegian, fortunately the main NY case is handled earlier */
        if (!foundVariant) {
            if (parser.getLanguage().equals("nb") && parser.getVariant().equals("NY")) {
                parser.setBaseName(lscvToID("nn", parser.getScript(), parser.getCountry(), null));
            }
        }

        return parser.getName();
    }

    /**
     * {@icu} Given a keyword and a value, return a new locale with an updated
     * keyword and value.  If the keyword is null, this removes all keywords from the locale id.
     * Otherwise, if the value is null, this removes the value for this keyword from the
     * locale id.  Otherwise, this adds/replaces the value for this keyword in the locale id.
     * The keyword and value must not be empty.
     *
     * <p>Related: {@link #getBaseName()} returns the locale ID string with all keywords removed.
     *
     * @param keyword the keyword to add/remove, or null to remove all keywords.
     * @param value the value to add/set, or null to remove this particular keyword.
     * @return the updated locale
     * @stable ICU 3.2
     */
    public ULocale setKeywordValue(String keyword, String value) {
        return new ULocale(setKeywordValue(localeID, keyword, value), (Locale)null);
    }

    /**
     * Given a locale id, a keyword, and a value, return a new locale id with an updated
     * keyword and value.  If the keyword is null, this removes all keywords from the locale id.
     * Otherwise, if the value is null, this removes the value for this keyword from the
     * locale id.  Otherwise, this adds/replaces the value for this keyword in the locale id.
     * The keyword and value must not be empty.
     *
     * <p>Related: {@link #getBaseName(String)} returns the locale ID string with all keywords removed.
     *
     * @param localeID the locale id to modify
     * @param keyword the keyword to add/remove, or null to remove all keywords.
     * @param value the value to add/set, or null to remove this particular keyword.
     * @return the updated locale id
     * @stable ICU 3.2
     */
    public static String setKeywordValue(String localeID, String keyword, String value) {
        LocaleIDParser parser = new LocaleIDParser(localeID);
        parser.setKeywordValue(keyword, value);
        return parser.getName();
    }

    /*
     * Given a locale id, a keyword, and a value, return a new locale id with an updated
     * keyword and value, if the keyword does not already have a value.  The keyword and
     * value must not be null or empty.
     * @param localeID the locale id to modify
     * @param keyword the keyword to add, if not already present
     * @param value the value to add, if not already present
     * @return the updated locale id
     */
/*    private static String defaultKeywordValue(String localeID, String keyword, String value) {
        LocaleIDParser parser = new LocaleIDParser(localeID);
        parser.defaultKeywordValue(keyword, value);
        return parser.getName();
    }*/

    /**
     * Returns a three-letter abbreviation for this locale's language.  If the locale
     * doesn't specify a language, returns the empty string.  Otherwise, returns
     * a lowercase ISO 639-2/T language code.
     * The ISO 639-2 language codes can be found on-line at
     *   <a href="ftp://dkuug.dk/i18n/iso-639-2.txt"><code>ftp://dkuug.dk/i18n/iso-639-2.txt</code></a>
     * @exception MissingResourceException Throws MissingResourceException if the
     * three-letter language abbreviation is not available for this locale.
     * @stable ICU 3.0
     */
    public String getISO3Language(){
        return getISO3Language(localeID);
    }

    /**
     * {@icu} Returns a three-letter abbreviation for this locale's language.  If the locale
     * doesn't specify a language, returns the empty string.  Otherwise, returns
     * a lowercase ISO 639-2/T language code.
     * The ISO 639-2 language codes can be found on-line at
     *   <a href="ftp://dkuug.dk/i18n/iso-639-2.txt"><code>ftp://dkuug.dk/i18n/iso-639-2.txt</code></a>
     * @exception MissingResourceException Throws MissingResourceException if the
     * three-letter language abbreviation is not available for this locale.
     * @stable ICU 3.0
     */
    public static String getISO3Language(String localeID) {
        return LocaleIDs.getISO3Language(getLanguage(localeID));
    }

    /**
     * Returns a three-letter abbreviation for this locale's country/region.  If the locale
     * doesn't specify a country, returns the empty string.  Otherwise, returns
     * an uppercase ISO 3166 3-letter country code.
     * @exception MissingResourceException Throws MissingResourceException if the
     * three-letter country abbreviation is not available for this locale.
     * @stable ICU 3.0
     */
    public String getISO3Country() {
        return getISO3Country(localeID);
    }

    /**
     * {@icu} Returns a three-letter abbreviation for this locale's country/region.  If the locale
     * doesn't specify a country, returns the empty string.  Otherwise, returns
     * an uppercase ISO 3166 3-letter country code.
     * @exception MissingResourceException Throws MissingResourceException if the
     * three-letter country abbreviation is not available for this locale.
     * @stable ICU 3.0
     */
    public static String getISO3Country(String localeID) {
        return LocaleIDs.getISO3Country(getCountry(localeID));
    }

    /**
     * Pairs of (language subtag, + or -) for finding out fast if common languages
     * are LTR (minus) or RTL (plus).
     */
    private static final String LANG_DIR_STRING =
            "root-en-es-pt-zh-ja-ko-de-fr-it-ar+he+fa+ru-nl-pl-th-tr-";

    /**
     * {@icu} Returns whether this locale's script is written right-to-left.
     * If there is no script subtag, then the likely script is used,
     * see {@link #addLikelySubtags(ULocale)}.
     * If no likely script is known, then false is returned.
     *
     * <p>A script is right-to-left according to the CLDR script metadata
     * which corresponds to whether the script's letters have Bidi_Class=R or AL.
     *
     * <p>Returns true for "ar" and "en-Hebr", false for "zh" and "fa-Cyrl".
     *
     * @return true if the locale's script is written right-to-left
     * @draft ICU 54
     * @provisional This API might change or be removed in a future release.
     */
    public boolean isRightToLeft() {
        String script = getScript();
        if (script.length() == 0) {
            // Fastpath: We know the likely scripts and their writing direction
            // for some common languages.
            String lang = getLanguage();
            if (lang.length() == 0) {
                return false;
            }
            int langIndex = LANG_DIR_STRING.indexOf(lang);
            if (langIndex >= 0) {
                switch (LANG_DIR_STRING.charAt(langIndex + lang.length())) {
                case '-': return false;
                case '+': return true;
                default: break;  // partial match of a longer code
                }
            }
            // Otherwise, find the likely script.
            ULocale likely = addLikelySubtags(this);
            script = likely.getScript();
            if (script.length() == 0) {
                return false;
            }
        }
        int scriptCode = UScript.getCodeFromName(script);
        return UScript.isRightToLeft(scriptCode);
    }

    // display names

    /**
     * Returns this locale's language localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized language name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayLanguage() {
        return getDisplayLanguageInternal(this, getDefault(Category.DISPLAY), false);
    }

    /**
     * Returns this locale's language localized for display in the provided locale.
     * @param displayLocale the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 3.0
     */
    public String getDisplayLanguage(ULocale displayLocale) {
        return getDisplayLanguageInternal(this, displayLocale, false);
    }

    /**
     * {@icu} Returns a locale's language localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose language will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 3.0
     */
    public static String getDisplayLanguage(String localeID, String displayLocaleID) {
        return getDisplayLanguageInternal(new ULocale(localeID), new ULocale(displayLocaleID),
                false);
    }

    /**
     * {@icu} Returns a locale's language localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose language will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 3.0
     */
    public static String getDisplayLanguage(String localeID, ULocale displayLocale) {
        return getDisplayLanguageInternal(new ULocale(localeID), displayLocale, false);
    }
    /**
     * {@icu} Returns this locale's language localized for display in the default <code>DISPLAY</code> locale.
     * If a dialect name is present in the data, then it is returned.
     * @return the localized language name.
     * @see Category#DISPLAY
     * @stable ICU 4.4
     */
    public String getDisplayLanguageWithDialect() {
        return getDisplayLanguageInternal(this, getDefault(Category.DISPLAY), true);
    }

    /**
     * {@icu} Returns this locale's language localized for display in the provided locale.
     * If a dialect name is present in the data, then it is returned.
     * @param displayLocale the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 4.4
     */
    public String getDisplayLanguageWithDialect(ULocale displayLocale) {
        return getDisplayLanguageInternal(this, displayLocale, true);
    }

    /**
     * {@icu} Returns a locale's language localized for display in the provided locale.
     * If a dialect name is present in the data, then it is returned.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose language will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 4.4
     */
    public static String getDisplayLanguageWithDialect(String localeID, String displayLocaleID) {
        return getDisplayLanguageInternal(new ULocale(localeID), new ULocale(displayLocaleID),
                true);
    }

    /**
     * {@icu} Returns a locale's language localized for display in the provided locale.
     * If a dialect name is present in the data, then it is returned.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose language will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized language name.
     * @stable ICU 4.4
     */
    public static String getDisplayLanguageWithDialect(String localeID, ULocale displayLocale) {
        return getDisplayLanguageInternal(new ULocale(localeID), displayLocale, true);
    }

    private static String getDisplayLanguageInternal(ULocale locale, ULocale displayLocale,
            boolean useDialect) {
        String lang = useDialect ? locale.getBaseName() : locale.getLanguage();
        return LocaleDisplayNames.getInstance(displayLocale).languageDisplayName(lang);
    }

    /**
     * Returns this locale's script localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized script name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayScript() {
        return getDisplayScriptInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * {@icu} Returns this locale's script localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized script name.
     * @see Category#DISPLAY
     * @internal
     * @deprecated This API is ICU internal only.
     */
    @Deprecated
    public String getDisplayScriptInContext() {
        return getDisplayScriptInContextInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * Returns this locale's script localized for display in the provided locale.
     * @param displayLocale the locale in which to display the name.
     * @return the localized script name.
     * @stable ICU 3.0
     */
    public String getDisplayScript(ULocale displayLocale) {
        return getDisplayScriptInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns this locale's script localized for display in the provided locale.
     * @param displayLocale the locale in which to display the name.
     * @return the localized script name.
     * @internal
     * @deprecated This API is ICU internal only.
     */
    @Deprecated
    public String getDisplayScriptInContext(ULocale displayLocale) {
        return getDisplayScriptInContextInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns a locale's script localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose script will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized script name.
     * @stable ICU 3.0
     */
    public static String getDisplayScript(String localeID, String displayLocaleID) {
        return getDisplayScriptInternal(new ULocale(localeID), new ULocale(displayLocaleID));
    }
    /**
     * {@icu} Returns a locale's script localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose script will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized script name.
     * @internal
     * @deprecated This API is ICU internal only.
     */
    @Deprecated
    public static String getDisplayScriptInContext(String localeID, String displayLocaleID) {
        return getDisplayScriptInContextInternal(new ULocale(localeID), new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns a locale's script localized for display in the provided locale.
     * @param localeID the id of the locale whose script will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized script name.
     * @stable ICU 3.0
     */
    public static String getDisplayScript(String localeID, ULocale displayLocale) {
        return getDisplayScriptInternal(new ULocale(localeID), displayLocale);
    }
    /**
     * {@icu} Returns a locale's script localized for display in the provided locale.
     * @param localeID the id of the locale whose script will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized script name.
     * @internal
     * @deprecated This API is ICU internal only.
     */
    @Deprecated
    public static String getDisplayScriptInContext(String localeID, ULocale displayLocale) {
        return getDisplayScriptInContextInternal(new ULocale(localeID), displayLocale);
    }

    // displayLocaleID is canonical, localeID need not be since parsing will fix this.
    private static String getDisplayScriptInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale)
            .scriptDisplayName(locale.getScript());
    }

    private static String getDisplayScriptInContextInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale)
            .scriptDisplayNameInContext(locale.getScript());
    }

    /**
     * Returns this locale's country localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized country name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayCountry() {
        return getDisplayCountryInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * Returns this locale's country localized for display in the provided locale.
     * @param displayLocale the locale in which to display the name.
     * @return the localized country name.
     * @stable ICU 3.0
     */
    public String getDisplayCountry(ULocale displayLocale){
        return getDisplayCountryInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns a locale's country localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose country will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized country name.
     * @stable ICU 3.0
     */
    public static String getDisplayCountry(String localeID, String displayLocaleID) {
        return getDisplayCountryInternal(new ULocale(localeID), new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns a locale's country localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose country will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized country name.
     * @stable ICU 3.0
     */
    public static String getDisplayCountry(String localeID, ULocale displayLocale) {
        return getDisplayCountryInternal(new ULocale(localeID), displayLocale);
    }

    // displayLocaleID is canonical, localeID need not be since parsing will fix this.
    private static String getDisplayCountryInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale)
            .regionDisplayName(locale.getCountry());
    }

    /**
     * Returns this locale's variant localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized variant name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayVariant() {
        return getDisplayVariantInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * Returns this locale's variant localized for display in the provided locale.
     * @param displayLocale the locale in which to display the name.
     * @return the localized variant name.
     * @stable ICU 3.0
     */
    public String getDisplayVariant(ULocale displayLocale) {
        return getDisplayVariantInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns a locale's variant localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose variant will be displayed
     * @param displayLocaleID the id of the locale in which to display the name.
     * @return the localized variant name.
     * @stable ICU 3.0
     */
    public static String getDisplayVariant(String localeID, String displayLocaleID){
        return getDisplayVariantInternal(new ULocale(localeID), new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns a locale's variant localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose variant will be displayed.
     * @param displayLocale the locale in which to display the name.
     * @return the localized variant name.
     * @stable ICU 3.0
     */
    public static String getDisplayVariant(String localeID, ULocale displayLocale) {
        return getDisplayVariantInternal(new ULocale(localeID), displayLocale);
    }

    private static String getDisplayVariantInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale)
            .variantDisplayName(locale.getVariant());
    }

    /**
     * {@icu} Returns a keyword localized for display in the default <code>DISPLAY</code> locale.
     * @param keyword the keyword to be displayed.
     * @return the localized keyword name.
     * @see #getKeywords()
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public static String getDisplayKeyword(String keyword) {
        return getDisplayKeywordInternal(keyword, getDefault(Category.DISPLAY));
    }

    /**
     * {@icu} Returns a keyword localized for display in the specified locale.
     * @param keyword the keyword to be displayed.
     * @param displayLocaleID the id of the locale in which to display the keyword.
     * @return the localized keyword name.
     * @see #getKeywords(String)
     * @stable ICU 3.0
     */
    public static String getDisplayKeyword(String keyword, String displayLocaleID) {
        return getDisplayKeywordInternal(keyword, new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns a keyword localized for display in the specified locale.
     * @param keyword the keyword to be displayed.
     * @param displayLocale the locale in which to display the keyword.
     * @return the localized keyword name.
     * @see #getKeywords(String)
     * @stable ICU 3.0
     */
    public static String getDisplayKeyword(String keyword, ULocale displayLocale) {
        return getDisplayKeywordInternal(keyword, displayLocale);
    }

    private static String getDisplayKeywordInternal(String keyword, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale).keyDisplayName(keyword);
    }

    /**
     * {@icu} Returns a keyword value localized for display in the default <code>DISPLAY</code> locale.
     * @param keyword the keyword whose value is to be displayed.
     * @return the localized value name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayKeywordValue(String keyword) {
        return getDisplayKeywordValueInternal(this, keyword, getDefault(Category.DISPLAY));
    }

    /**
     * {@icu} Returns a keyword value localized for display in the specified locale.
     * @param keyword the keyword whose value is to be displayed.
     * @param displayLocale the locale in which to display the value.
     * @return the localized value name.
     * @stable ICU 3.0
     */
    public String getDisplayKeywordValue(String keyword, ULocale displayLocale) {
        return getDisplayKeywordValueInternal(this, keyword, displayLocale);
    }

    /**
     * {@icu} Returns a keyword value localized for display in the specified locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose keyword value is to be displayed.
     * @param keyword the keyword whose value is to be displayed.
     * @param displayLocaleID the id of the locale in which to display the value.
     * @return the localized value name.
     * @stable ICU 3.0
     */
    public static String getDisplayKeywordValue(String localeID, String keyword,
            String displayLocaleID) {
        return getDisplayKeywordValueInternal(new ULocale(localeID), keyword,
                new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns a keyword value localized for display in the specified locale.
     * This is a cover for the ICU4C API.
     * @param localeID the id of the locale whose keyword value is to be displayed.
     * @param keyword the keyword whose value is to be displayed.
     * @param displayLocale the id of the locale in which to display the value.
     * @return the localized value name.
     * @stable ICU 3.0
     */
    public static String getDisplayKeywordValue(String localeID, String keyword,
            ULocale displayLocale) {
        return getDisplayKeywordValueInternal(new ULocale(localeID), keyword, displayLocale);
    }

    // displayLocaleID is canonical, localeID need not be since parsing will fix this.
    private static String getDisplayKeywordValueInternal(ULocale locale, String keyword,
            ULocale displayLocale) {
        keyword = AsciiUtil.toLowerString(keyword.trim());
        String value = locale.getKeywordValue(keyword);
        return LocaleDisplayNames.getInstance(displayLocale).keyValueDisplayName(keyword, value);
    }

    /**
     * Returns this locale name localized for display in the default <code>DISPLAY</code> locale.
     * @return the localized locale name.
     * @see Category#DISPLAY
     * @stable ICU 3.0
     */
    public String getDisplayName() {
        return getDisplayNameInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * Returns this locale name localized for display in the provided locale.
     * @param displayLocale the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 3.0
     */
    public String getDisplayName(ULocale displayLocale) {
        return getDisplayNameInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns the locale ID localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the locale whose name is to be displayed.
     * @param displayLocaleID the id of the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 3.0
     */
    public static String getDisplayName(String localeID, String displayLocaleID) {
        return getDisplayNameInternal(new ULocale(localeID), new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns the locale ID localized for display in the provided locale.
     * This is a cover for the ICU4C API.
     * @param localeID the locale whose name is to be displayed.
     * @param displayLocale the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 3.0
     */
    public static String getDisplayName(String localeID, ULocale displayLocale) {
        return getDisplayNameInternal(new ULocale(localeID), displayLocale);
    }

    private static String getDisplayNameInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale).localeDisplayName(locale);
    }

    /**
     * {@icu} Returns this locale name localized for display in the default <code>DISPLAY</code> locale.
     * If a dialect name is present in the locale data, then it is returned.
     * @return the localized locale name.
     * @see Category#DISPLAY
     * @stable ICU 4.4
     */
    public String getDisplayNameWithDialect() {
        return getDisplayNameWithDialectInternal(this, getDefault(Category.DISPLAY));
    }

    /**
     * {@icu} Returns this locale name localized for display in the provided locale.
     * If a dialect name is present in the locale data, then it is returned.
     * @param displayLocale the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 4.4
     */
    public String getDisplayNameWithDialect(ULocale displayLocale) {
        return getDisplayNameWithDialectInternal(this, displayLocale);
    }

    /**
     * {@icu} Returns the locale ID localized for display in the provided locale.
     * If a dialect name is present in the locale data, then it is returned.
     * This is a cover for the ICU4C API.
     * @param localeID the locale whose name is to be displayed.
     * @param displayLocaleID the id of the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 4.4
     */
    public static String getDisplayNameWithDialect(String localeID, String displayLocaleID) {
        return getDisplayNameWithDialectInternal(new ULocale(localeID),
                new ULocale(displayLocaleID));
    }

    /**
     * {@icu} Returns the locale ID localized for display in the provided locale.
     * If a dialect name is present in the locale data, then it is returned.
     * This is a cover for the ICU4C API.
     * @param localeID the locale whose name is to be displayed.
     * @param displayLocale the locale in which to display the locale name.
     * @return the localized locale name.
     * @stable ICU 4.4
     */
    public static String getDisplayNameWithDialect(String localeID, ULocale displayLocale) {
        return getDisplayNameWithDialectInternal(new ULocale(localeID), displayLocale);
    }

    private static String getDisplayNameWithDialectInternal(ULocale locale, ULocale displayLocale) {
        return LocaleDisplayNames.getInstance(displayLocale, DialectHandling.DIALECT_NAMES)
            .localeDisplayName(locale);
    }

    /**
     * {@icu} Returns this locale's layout orientation for characters.  The possible
     * values are "left-to-right", "right-to-left", "top-to-bottom" or
     * "bottom-to-top".
     * @return The locale's layout orientation for characters.
     * @stable ICU 4.0
     */
    public String getCharacterOrientation() {
        return ICUResourceTableAccess.getTableString(ICUResourceBundle.ICU_BASE_NAME, this,
                "layout", "characters");
    }

    /**
     * {@icu} Returns this locale's layout orientation for lines.  The possible
     * values are "left-to-right", "right-to-left", "top-to-bottom" or
     * "bottom-to-top".
     * @return The locale's layout orientation for lines.
     * @stable ICU 4.0
     */
    public String getLineOrientation() {
        return ICUResourceTableAccess.getTableString(ICUResourceBundle.ICU_BASE_NAME, this,
                "layout", "lines");
    }

    /**
     * {@icu} Selector for <tt>getLocale()</tt> indicating the locale of the
     * resource containing the data.  This is always at or above the
     * valid locale.  If the valid locale does not contain the
     * specific data being requested, then the actual locale will be
     * above the valid locale.  If the object was not constructed from
     * locale data, then the valid locale is <i>null</i>.
     *
     * @draft ICU 2.8 (retain)
     * @provisional This API might change or be removed in a future release.
     */
    public static Type ACTUAL_LOCALE = new Type();

    /**
     * {@icu} Selector for <tt>getLocale()</tt> indicating the most specific
     * locale for which any data exists.  This is always at or above
     * the requested locale, and at or below the actual locale.  If
     * the requested locale does not correspond to any resource data,
     * then the valid locale will be above the requested locale.  If
     * the object was not constructed from locale data, then the
     * actual locale is <i>null</i>.
     *
     * <p>Note: The valid locale will be returned correctly in ICU
     * 3.0 or later.  In ICU 2.8, it is not returned correctly.
     * @draft ICU 2.8 (retain)
     * @provisional This API might change or be removed in a future release.
     */
    public static Type VALID_LOCALE = new Type();

    /**
     * Opaque selector enum for <tt>getLocale()</tt>.
     * @see com.ibm.icu.util.ULocale
     * @see com.ibm.icu.util.ULocale#ACTUAL_LOCALE
     * @see com.ibm.icu.util.ULocale#VALID_LOCALE
     * @draft ICU 2.8 (retainAll)
     * @provisional This API might change or be removed in a future release.
     */
    public static final class Type {
        private Type() {}
    }

  /**
    * {@icu} Based on a HTTP formatted list of acceptable locales, determine an available
    * locale for the user.  NullPointerException is thrown if acceptLanguageList or
    * availableLocales is null.  If fallback is non-null, it will contain true if a
    * fallback locale (one not in the acceptLanguageList) was returned.  The value on
    * entry is ignored.  ULocale will be one of the locales in availableLocales, or the
    * ROOT ULocale if if a ROOT locale was used as a fallback (because nothing else in
    * availableLocales matched).  No ULocale array element should be null; behavior is
    * undefined if this is the case.
    * @param acceptLanguageList list in HTTP "Accept-Language:" format of acceptable locales
    * @param availableLocales list of available locales. One of these will be returned.
    * @param fallback if non-null, a 1-element array containing a boolean to be set with
    * the fallback status
    * @return one of the locales from the availableLocales list, or null if none match
    * @stable ICU 3.4
    */
    public static ULocale acceptLanguage(String acceptLanguageList, ULocale[] availableLocales,
                                         boolean[] fallback) {
        if (acceptLanguageList == null) {
            throw new NullPointerException();
        }
        ULocale acceptList[] = null;
        try {
            acceptList = parseAcceptLanguage(acceptLanguageList, true);
        } catch (ParseException pe) {
            acceptList = null;
        }
        if (acceptList == null) {
            return null;
        }
        return acceptLanguage(acceptList, availableLocales, fallback);
    }

    /**
    * {@icu} Based on a list of acceptable locales, determine an available locale for the
    * user.  NullPointerException is thrown if acceptLanguageList or availableLocales is
    * null.  If fallback is non-null, it will contain true if a fallback locale (one not
    * in the acceptLanguageList) was returned.  The value on entry is ignored.  ULocale
    * will be one of the locales in availableLocales, or the ROOT ULocale if if a ROOT
    * locale was used as a fallback (because nothing else in availableLocales matched).
    * No ULocale array element should be null; behavior is undefined if this is the case.
    * @param acceptLanguageList list of acceptable locales
    * @param availableLocales list of available locales. One of these will be returned.
    * @param fallback if non-null, a 1-element array containing a boolean to be set with
    * the fallback status
    * @return one of the locales from the availableLocales list, or null if none match
    * @stable ICU 3.4
    */

    public static ULocale acceptLanguage(ULocale[] acceptLanguageList, ULocale[]
    availableLocales, boolean[] fallback) {
        // fallbacklist
        int i,j;
        if(fallback != null) {
            fallback[0]=true;
        }
        for(i=0;i<acceptLanguageList.length;i++) {
            ULocale aLocale = acceptLanguageList[i];
            boolean[] setFallback = fallback;
            do {
                for(j=0;j<availableLocales.length;j++) {
                    if(availableLocales[j].equals(aLocale)) {
                        if(setFallback != null) {
                            setFallback[0]=false; // first time with this locale - not a fallback.
                        }
                        return availableLocales[j];
                    }
                    // compare to scriptless alias, so locales such as
                    // zh_TW, zh_CN are considered as available locales - see #7190
                    if (aLocale.getScript().length() == 0
                            && availableLocales[j].getScript().length() > 0
                            && availableLocales[j].getLanguage().equals(aLocale.getLanguage())
                            && availableLocales[j].getCountry().equals(aLocale.getCountry())
                            && availableLocales[j].getVariant().equals(aLocale.getVariant())) {
                        ULocale minAvail = ULocale.minimizeSubtags(availableLocales[j]);
                        if (minAvail.getScript().length() == 0) {
                            if(setFallback != null) {
                                setFallback[0] = false; // not a fallback.
                            }
                            return aLocale;
                        }
                    }
                }
                Locale loc = aLocale.toLocale();
                Locale parent = LocaleUtility.fallback(loc);
                if(parent != null) {
                    aLocale = new ULocale(parent);
                } else {
                    aLocale = null;
                }
                setFallback = null; // Do not set fallback in later iterations
            } while (aLocale != null);
        }
        return null;
    }

   /**
    * {@icu} Based on a HTTP formatted list of acceptable locales, determine an available
    * locale for the user.  NullPointerException is thrown if acceptLanguageList or
    * availableLocales is null.  If fallback is non-null, it will contain true if a
    * fallback locale (one not in the acceptLanguageList) was returned.  The value on
    * entry is ignored.  ULocale will be one of the locales in availableLocales, or the
    * ROOT ULocale if if a ROOT locale was used as a fallback (because nothing else in
    * availableLocales matched).  No ULocale array element should be null; behavior is
    * undefined if this is the case.  This function will choose a locale from the
    * ULocale.getAvailableLocales() list as available.
    * @param acceptLanguageList list in HTTP "Accept-Language:" format of acceptable locales
    * @param fallback if non-null, a 1-element array containing a boolean to be set with
    * the fallback status
    * @return one of the locales from the ULocale.getAvailableLocales() list, or null if
    * none match
    * @stable ICU 3.4
    */
    public static ULocale acceptLanguage(String acceptLanguageList, boolean[] fallback) {
        return acceptLanguage(acceptLanguageList, ULocale.getAvailableLocales(),
                                fallback);
    }

   /**
    * {@icu} Based on an ordered array of acceptable locales, determine an available
    * locale for the user.  NullPointerException is thrown if acceptLanguageList or
    * availableLocales is null.  If fallback is non-null, it will contain true if a
    * fallback locale (one not in the acceptLanguageList) was returned.  The value on
    * entry is ignored.  ULocale will be one of the locales in availableLocales, or the
    * ROOT ULocale if if a ROOT locale was used as a fallback (because nothing else in
    * availableLocales matched).  No ULocale array element should be null; behavior is
    * undefined if this is the case.  This function will choose a locale from the
    * ULocale.getAvailableLocales() list as available.
    * @param acceptLanguageList ordered array of acceptable locales (preferred are listed first)
    * @param fallback if non-null, a 1-element array containing a boolean to be set with
    * the fallback status
    * @return one of the locales from the ULocale.getAvailableLocales() list, or null if none match
    * @stable ICU 3.4
    */
    public static ULocale acceptLanguage(ULocale[] acceptLanguageList, boolean[] fallback) {
        return acceptLanguage(acceptLanguageList, ULocale.getAvailableLocales(),
                fallback);
    }

    /**
     * Package local method used for parsing Accept-Language string
     */
    static ULocale[] parseAcceptLanguage(String acceptLanguage, boolean isLenient) 
        throws ParseException {
        class ULocaleAcceptLanguageQ implements Comparable<ULocaleAcceptLanguageQ> {
            private double q;
            private double serial;
            public ULocaleAcceptLanguageQ(double theq, int theserial) {
                q = theq;
                serial = theserial;
            }
            public int compareTo(ULocaleAcceptLanguageQ other) {
                if (q > other.q) { // reverse - to sort in descending order
                    return -1;
                } else if (q < other.q) {
                    return 1;
                }
                if (serial < other.serial) {
                    return -1;
                } else if (serial > other.serial) {
                    return 1;
                } else {
                    return 0; // same object
                }
            }
        }

        // parse out the acceptLanguage into an array
        TreeMap<ULocaleAcceptLanguageQ, ULocale> map = 
            new TreeMap<ULocaleAcceptLanguageQ, ULocale>();
        StringBuilder languageRangeBuf = new StringBuilder();
        StringBuilder qvalBuf = new StringBuilder();
        int state = 0;
        acceptLanguage += ","; // append comma to simplify the parsing code
        int n;
        boolean subTag = false;
        boolean q1 = false;
        for (n = 0; n < acceptLanguage.length(); n++) {
            boolean gotLanguageQ = false;
            char c = acceptLanguage.charAt(n);
            switch (state) {
            case 0: // before language-range start
                if (('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z')) {
                    // in language-range
                    languageRangeBuf.append(c);
                    state = 1;
                    subTag = false;
                } else if (c == '*') {
                    languageRangeBuf.append(c);
                    state = 2;
                } else if (c != ' ' && c != '\t') {
                    // invalid character
                    state = -1;
                }
                break;
            case 1: // in language-range
                if (('A' <= c && c <= 'Z') || ('a' <= c && c <= 'z')) {
                    languageRangeBuf.append(c);
                } else if (c == '-') {
                    subTag = true;
                    languageRangeBuf.append(c);
                } else if (c == '_') {
                    if (isLenient) {
                        subTag = true;
                        languageRangeBuf.append(c);
                    } else {
                        state = -1;
                    }
                } else if ('0' <= c && c <= '9') {
                    if (subTag) {
                        languageRangeBuf.append(c);
                    } else {
                        // DIGIT is allowed only in language sub tag
                        state = -1;
                    }
                } else if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c == ' ' || c == '\t') {
                    // language-range end
                    state = 3;
                } else if (c == ';') {
                    // before q
                    state = 4;
                } else {
                    // invalid character for language-range
                    state = -1;
                }
                break;
            case 2: // saw wild card range
                if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c == ' ' || c == '\t') {
                    // language-range end
                    state = 3;
                } else if (c == ';') {
                    // before q
                    state = 4;
                } else {
                    // invalid
                    state = -1;
                }
                break;
            case 3: // language-range end
                if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c == ';') {
                    // before q
                    state =4;
                } else if (c != ' ' && c != '\t') {
                    // invalid
                    state = -1;
                }
                break;
            case 4: // before q
                if (c == 'q') {
                    // before equal
                    state = 5;
                } else if (c != ' ' && c != '\t') {
                    // invalid
                    state = -1;
                }
                break;
            case 5: // before equal
                if (c == '=') {
                    // before q value
                    state = 6;
                } else if (c != ' ' && c != '\t') {
                    // invalid
                    state = -1;
                }
                break;
            case 6: // before q value
                if (c == '0') {
                    // q value start with 0
                    q1 = false;
                    qvalBuf.append(c);
                    state = 7;
                } else if (c == '1') {
                    // q value start with 1
                    qvalBuf.append(c);
                    state = 7;
                } else if (c == '.') {
                    if (isLenient) {
                        qvalBuf.append(c);
                        state = 8;
                    } else {
                        state = -1;
                    }
                } else if (c != ' ' && c != '\t') {
                    // invalid
                    state = -1;
                }
                break;
            case 7: // q value start
                if (c == '.') {
                    // before q value fraction part
                    qvalBuf.append(c);
                    state = 8;
                } else if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c == ' ' || c == '\t') {
                    // after q value
                    state = 10;
                } else {
                    // invalid
                    state = -1;
                }
                break;
            case 8: // before q value fraction part
                if ('0' <= c || c <= '9') {
                    if (q1 && c != '0' && !isLenient) {
                        // if q value starts with 1, the fraction part must be 0
                        state = -1;
                    } else {
                        // in q value fraction part
                        qvalBuf.append(c);
                        state = 9;
                    }
                } else {
                    // invalid
                    state = -1;
                }
                break;
            case 9: // in q value fraction part
                if ('0' <= c && c <= '9') {
                    if (q1 && c != '0') {
                        // if q value starts with 1, the fraction part must be 0
                        state = -1;
                    } else {
                        qvalBuf.append(c);
                    }
                } else if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c == ' ' || c == '\t') {
                    // after q value
                    state = 10;
                } else {
                    // invalid
                    state = -1;
                }
                break;
            case 10: // after q value
                if (c == ',') {
                    // language-q end
                    gotLanguageQ = true;
                } else if (c != ' ' && c != '\t') {
                    // invalid
                    state = -1;
                }
                break;
            }
            if (state == -1) {
                // error state
                throw new ParseException("Invalid Accept-Language", n);
            }
            if (gotLanguageQ) {
                double q = 1.0;
                if (qvalBuf.length() != 0) {
                    try {
                        q = Double.parseDouble(qvalBuf.toString());
                    } catch (NumberFormatException nfe) {
                        // Already validated, so it should never happen
                        q = 1.0;
                    }
                    if (q > 1.0) {
                        q = 1.0;
                    }
                }
                if (languageRangeBuf.charAt(0) != '*') {
                    int serial = map.size();
                    ULocaleAcceptLanguageQ entry = new ULocaleAcceptLanguageQ(q, serial);
                    // sort in reverse order..   1.0, 0.9, 0.8 .. etc
                    map.put(entry, new ULocale(canonicalize(languageRangeBuf.toString())));
                }

                // reset buffer and parse state
                languageRangeBuf.setLength(0);
                qvalBuf.setLength(0);
                state = 0;
            }
        }
        if (state != 0) {
            // Well, the parser should handle all cases.  So just in case.
            throw new ParseException("Invalid AcceptlLanguage", n);
        }

        // pull out the map
        ULocale acceptList[] = map.values().toArray(new ULocale[map.size()]);
        return acceptList;
    }

    private static final String UNDEFINED_LANGUAGE = "und";
    private static final String UNDEFINED_SCRIPT = "Zzzz";
    private static final String UNDEFINED_REGION = "ZZ";

    /**
     * {@icu} Adds the likely subtags for a provided locale ID, per the algorithm
     * described in the following CLDR technical report:
     *
     *   http://www.unicode.org/reports/tr35/#Likely_Subtags
     *
     * If the provided ULocale instance is already in the maximal form, or there is no
     * data available available for maximization, it will be returned.  For example,
     * "und-Zzzz" cannot be maximized, since there is no reasonable maximization.
     * Otherwise, a new ULocale instance with the maximal form is returned.
     *
     * Examples:
     *
     * "en" maximizes to "en_Latn_US"
     *
     * "de" maximizes to "de_Latn_US"
     *
     * "sr" maximizes to "sr_Cyrl_RS"
     *
     * "sh" maximizes to "sr_Latn_RS" (Note this will not reverse.)
     *
     * "zh_Hani" maximizes to "zh_Hans_CN" (Note this will not reverse.)
     *
     * @param loc The ULocale to maximize
     * @return The maximized ULocale instance.
     * @stable ICU 4.0
     */
    public static ULocale addLikelySubtags(ULocale loc) {
        String[] tags = new String[3];
        String trailing = null;

        int trailingIndex = parseTagString(
            loc.localeID,
            tags);

        if (trailingIndex < loc.localeID.length()) {
            trailing = loc.localeID.substring(trailingIndex);
        }

        String newLocaleID =
            createLikelySubtagsString(
                tags[0],
                tags[1],
                tags[2],
                trailing);

        return newLocaleID == null ? loc : new ULocale(newLocaleID);
    }

    /**
     * {@icu} Minimizes the subtags for a provided locale ID, per the algorithm described
     * in the following CLDR technical report:<blockquote>
     *
     *   <a href="http://www.unicode.org/reports/tr35/#Likely_Subtags"
     *>http://www.unicode.org/reports/tr35/#Likely_Subtags</a></blockquote>
     *
     * If the provided ULocale instance is already in the minimal form, or there
     * is no data available for minimization, it will be returned.  Since the
     * minimization algorithm relies on proper maximization, see the comments
     * for addLikelySubtags for reasons why there might not be any data.
     *
     * Examples:<pre>
     *
     * "en_Latn_US" minimizes to "en"
     *
     * "de_Latn_US" minimizes to "de"
     *
     * "sr_Cyrl_RS" minimizes to "sr"
     *
     * "zh_Hant_TW" minimizes to "zh_TW" (The region is preferred to the
     * script, and minimizing to "zh" would imply "zh_Hans_CN".) </pre>
     *
     * @param loc The ULocale to minimize
     * @return The minimized ULocale instance.
     * @stable ICU 4.0
     */
    public static ULocale minimizeSubtags(ULocale loc) {
        String[] tags = new String[3];

        int trailingIndex = parseTagString(
                loc.localeID,
                tags);

        String originalLang = tags[0];
        String originalScript = tags[1];
        String originalRegion = tags[2];
        String originalTrailing = null;

        if (trailingIndex < loc.localeID.length()) {
            /*
             * Create a String that contains everything
             * after the language, script, and region.
             */
            originalTrailing = loc.localeID.substring(trailingIndex);
        }

        /**
         * First, we need to first get the maximization
         * by adding any likely subtags.
         **/
        String maximizedLocaleID =
            createLikelySubtagsString(
                originalLang,
                originalScript,
                originalRegion,
                null);

        /**
         * If maximization fails, there's nothing
         * we can do.
         **/
        if (isEmptyString(maximizedLocaleID)) {
            return loc;
        }
        else {
            /**
             * Start first with just the language.
             **/
            String tag =
                createLikelySubtagsString(
                    originalLang,
                    null,
                    null,
                    null);

            if (tag.equals(maximizedLocaleID)) {
                String newLocaleID =
                    createTagString(
                        originalLang,
                        null,
                        null,
                        originalTrailing);

                return new ULocale(newLocaleID);
            }
        }

        /**
         * Next, try the language and region.
         **/
        if (originalRegion.length() != 0) {

            String tag =
                createLikelySubtagsString(
                    originalLang,
                    null,
                    originalRegion,
                    null);

            if (tag.equals(maximizedLocaleID)) {
                String newLocaleID =
                    createTagString(
                        originalLang,
                        null,
                        originalRegion,
                        originalTrailing);

                return new ULocale(newLocaleID);
            }
        }

        /**
         * Finally, try the language and script.  This is our last chance,
         * since trying with all three subtags would only yield the
         * maximal version that we already have.
         **/
        if (originalRegion.length() != 0 &&
            originalScript.length() != 0) {

            String tag =
                createLikelySubtagsString(
                    originalLang,
                    originalScript,
                    null,
                    null);

            if (tag.equals(maximizedLocaleID)) {
                String newLocaleID =
                    createTagString(
                        originalLang,
                        originalScript,
                        null,
                        originalTrailing);

                return new ULocale(newLocaleID);
            }
        }

        return loc;
    }

    /**
     * A trivial utility function that checks for a null
     * reference or checks the length of the supplied String.
     *
     *   @param string The string to check
     *
     *   @return true if the String is empty, or if the reference is null.
     */
    private static boolean isEmptyString(String string) {
      return string == null || string.length() == 0;
    }

    /**
     * Append a tag to a StringBuilder, adding the separator if necessary.The tag must
     * not be a zero-length string.
     *
     * @param tag The tag to add.
     * @param buffer The output buffer.
     **/
    private static void appendTag(String tag, StringBuilder buffer) {
        if (buffer.length() != 0) {
            buffer.append(UNDERSCORE);
        }

        buffer.append(tag);
    }

    /**
     * Create a tag string from the supplied parameters.  The lang, script and region
     * parameters may be null references.
     *
     * If any of the language, script or region parameters are empty, and the alternateTags
     * parameter is not null, it will be parsed for potential language, script and region tags
     * to be used when constructing the new tag.  If the alternateTags parameter is null, or
     * it contains no language tag, the default tag for the unknown language is used.
     *
     * @param lang The language tag to use.
     * @param script The script tag to use.
     * @param region The region tag to use.
     * @param trailing Any trailing data to append to the new tag.
     * @param alternateTags A string containing any alternate tags.
     * @return The new tag string.
     **/
    private static String createTagString(String lang, String script, String region,
        String trailing, String alternateTags) {

        LocaleIDParser parser = null;
        boolean regionAppended = false;

        StringBuilder tag = new StringBuilder();

        if (!isEmptyString(lang)) {
            appendTag(
                lang,
                tag);
        }
        else if (isEmptyString(alternateTags)) {
            /*
             * Append the value for an unknown language, if
             * we found no language.
             */
            appendTag(
                UNDEFINED_LANGUAGE,
                tag);
        }
        else {
            parser = new LocaleIDParser(alternateTags);

            String alternateLang = parser.getLanguage();

            /*
             * Append the value for an unknown language, if
             * we found no language.
             */
            appendTag(
                !isEmptyString(alternateLang) ? alternateLang : UNDEFINED_LANGUAGE,
                tag);
        }

        if (!isEmptyString(script)) {
            appendTag(
                script,
                tag);
        }
        else if (!isEmptyString(alternateTags)) {
            /*
             * Parse the alternateTags string for the script.
             */
            if (parser == null) {
                parser = new LocaleIDParser(alternateTags);
            }

            String alternateScript = parser.getScript();

            if (!isEmptyString(alternateScript)) {
                appendTag(
                    alternateScript,
                    tag);
            }
        }

        if (!isEmptyString(region)) {
            appendTag(
                region,
                tag);

            regionAppended = true;
        }
        else if (!isEmptyString(alternateTags)) {
            /*
             * Parse the alternateTags string for the region.
             */
            if (parser == null) {
                parser = new LocaleIDParser(alternateTags);
            }

            String alternateRegion = parser.getCountry();

            if (!isEmptyString(alternateRegion)) {
                appendTag(
                    alternateRegion,
                    tag);

                regionAppended = true;
            }
        }

        if (trailing != null && trailing.length() > 1) {
            /*
             * The current ICU format expects two underscores
             * will separate the variant from the preceeding
             * parts of the tag, if there is no region.
             */
            int separators = 0;

            if (trailing.charAt(0) == UNDERSCORE) {
                if (trailing.charAt(1) == UNDERSCORE) {
                    separators = 2;
                }
                }
                else {
                    separators = 1;
                }

            if (regionAppended) {
                /*
                 * If we appended a region, we may need to strip
                 * the extra separator from the variant portion.
                 */
                if (separators == 2) {
                    tag.append(trailing.substring(1));
                }
                else {
                    tag.append(trailing);
                }
            }
            else {
                /*
                 * If we did not append a region, we may need to add
                 * an extra separator to the variant portion.
                 */
                if (separators == 1) {
                    tag.append(UNDERSCORE);
                }
                tag.append(trailing);
            }
        }

        return tag.toString();
    }

    /**
     * Create a tag string from the supplied parameters.  The lang, script and region
     * parameters may be null references.If the lang parameter is an empty string, the
     * default value for an unknown language is written to the output buffer.
     *
     * @param lang The language tag to use.
     * @param script The script tag to use.
     * @param region The region tag to use.
     * @param trailing Any trailing data to append to the new tag.
     * @return The new String.
     **/
    static String createTagString(String lang, String script, String region, String trailing) {
        return createTagString(lang, script, region, trailing, null);
    }

    /**
     * Parse the language, script, and region subtags from a tag string, and return the results.
     *
     * This function does not return the canonical strings for the unknown script and region.
     *
     * @param localeID The locale ID to parse.
     * @param tags An array of three String references to return the subtag strings.
     * @return The number of chars of the localeID parameter consumed.
     **/
    private static int parseTagString(String localeID, String tags[]) {
        LocaleIDParser parser = new LocaleIDParser(localeID);

        String lang = parser.getLanguage();
        String script = parser.getScript();
        String region = parser.getCountry();

        if (isEmptyString(lang)) {
            tags[0] = UNDEFINED_LANGUAGE;
        }
        else {
            tags[0] = lang;
        }

        if (script.equals(UNDEFINED_SCRIPT)) {
            tags[1] = "";
        }
        else {
            tags[1] = script;
        }

        if (region.equals(UNDEFINED_REGION)) {
            tags[2] = "";
        }
        else {
            tags[2] = region;
        }

        /*
         * Search for the variant.  If there is one, then return the index of
         * the preceeding separator.
         * If there's no variant, search for the keyword delimiter,
         * and return its index.  Otherwise, return the length of the
         * string.
         *
         * $TOTO(dbertoni) we need to take into account that we might
         * find a part of the language as the variant, since it can
         * can have a variant portion that is long enough to contain
         * the same characters as the variant.
         */
        String variant = parser.getVariant();

        if (!isEmptyString(variant)){
            int index = localeID.indexOf(variant);


            return  index > 0 ? index - 1 : index;
        }
        else
        {
            int index = localeID.indexOf('@');

            return index == -1 ? localeID.length() : index;
        }
    }

    private static String lookupLikelySubtags(String localeId) {
        UResourceBundle bundle =
            UResourceBundle.getBundleInstance(
                    ICUResourceBundle.ICU_BASE_NAME, "likelySubtags");
        try {
            return bundle.getString(localeId);
        }
        catch(MissingResourceException e) {
            return null;
        }
    }

    private static String createLikelySubtagsString(String lang, String script, String region,
        String variants) {

        /**
         * Try the language with the script and region first.
         */
        if (!isEmptyString(script) && !isEmptyString(region)) {

            String searchTag =
                createTagString(
                    lang,
                    script,
                    region,
                    null);

            String likelySubtags = lookupLikelySubtags(searchTag);

            /*
            if (likelySubtags == null) {
                if (likelySubtags2 != null) {
                    System.err.println("Tag mismatch: \"(null)\" \"" + likelySubtags2 + "\"");
                }
            }
            else if (likelySubtags2 == null) {
                System.err.println("Tag mismatch: \"" + likelySubtags + "\" \"(null)\"");
            }
            else if (!likelySubtags.equals(likelySubtags2)) {
                System.err.println("Tag mismatch: \"" + likelySubtags + "\" \"" + likelySubtags2 
                    + "\"");
            }
            */
            if (likelySubtags != null) {
                // Always use the language tag from the
                // maximal string, since it may be more
                // specific than the one provided.
                return createTagString(
                            null,
                            null,
                            null,
                            variants,
                            likelySubtags);
            }
        }

        /**
         * Try the language with just the script.
         **/
        if (!isEmptyString(script)) {

            String searchTag =
                createTagString(
                    lang,
                    script,
                    null,
                    null);

            String likelySubtags = lookupLikelySubtags(searchTag);
            if (likelySubtags != null) {
                // Always use the language tag from the
                // maximal string, since it may be more
                // specific than the one provided.
                return createTagString(
                            null,
                            null,
                            region,
                            variants,
                            likelySubtags);
            }
        }

        /**
         * Try the language with just the region.
         **/
        if (!isEmptyString(region)) {

            String searchTag =
                createTagString(
                    lang,
                    null,
                    region,
                    null);

            String likelySubtags = lookupLikelySubtags(searchTag);

            if (likelySubtags != null) {
                // Always use the language tag from the
                // maximal string, since it may be more
                // specific than the one provided.
                return createTagString(
                            null,
                            script,
                            null,
                            variants,
                            likelySubtags);
            }
        }

        /**
         * Finally, try just the language.
         **/
        {
            String searchTag =
                createTagString(
                    lang,
                    null,
                    null,
                    null);

            String likelySubtags = lookupLikelySubtags(searchTag);

            if (likelySubtags != null) {
                // Always use the language tag from the
                // maximal string, since it may be more
                // specific than the one provided.
                return createTagString(
                            null,
                            script,
                            region,
                            variants,
                            likelySubtags);
            }
        }

        return null;
    }

    // --------------------------------
    //      BCP47/OpenJDK APIs
    // --------------------------------

    /**
     * The key for the private use locale extension ('x').
     *
     * @see #getExtension(char)
     * @see Builder#setExtension(char, String)
     *
     * @stable ICU 4.2
     */
    public static final char PRIVATE_USE_EXTENSION = 'x';

    /**
     * The key for Unicode locale extension ('u').
     *
     * @see #getExtension(char)
     * @see Builder#setExtension(char, String)
     *
     * @stable ICU 4.2
     */
    public static final char UNICODE_LOCALE_EXTENSION = 'u';

    /**
     * Returns the extension (or private use) value associated with
     * the specified key, or null if there is no extension
     * associated with the key. To be well-formed, the key must be one
     * of <code>[0-9A-Za-z]</code>. Keys are case-insensitive, so
     * for example 'z' and 'Z' represent the same extension.
     *
     * @param key the extension key
     * @return The extension, or null if this locale defines no
     * extension for the specified key.
     * @throws IllegalArgumentException if key is not well-formed
     * @see #PRIVATE_USE_EXTENSION
     * @see #UNICODE_LOCALE_EXTENSION
     *
     * @stable ICU 4.2
     */
    public String getExtension(char key) {
        if (!LocaleExtensions.isValidKey(key)) {
            throw new IllegalArgumentException("Invalid extension key: " + key);
        }
        return extensions().getExtensionValue(key);
    }

    /**
     * Returns the set of extension keys associated with this locale, or the
     * empty set if it has no extensions. The returned set is unmodifiable.
     * The keys will all be lower-case.
     *
     * @return the set of extension keys, or the empty set if this locale has
     * no extensions
     * @stable ICU 4.2
     */
    public Set<Character> getExtensionKeys() {
        return extensions().getKeys();
    }

    /**
     * Returns the set of unicode locale attributes associated with
     * this locale, or the empty set if it has no attributes. The
     * returned set is unmodifiable.
     *
     * @return The set of attributes.
     * @stable ICU 4.6
     */
    public Set<String> getUnicodeLocaleAttributes() {
        return extensions().getUnicodeLocaleAttributes();
    }

    /**
     * Returns the Unicode locale type associated with the specified Unicode locale key
     * for this locale. Returns the empty string for keys that are defined with no type.
     * Returns null if the key is not defined. Keys are case-insensitive. The key must
     * be two alphanumeric characters ([0-9a-zA-Z]), or an IllegalArgumentException is
     * thrown.
     *
     * @param key the Unicode locale key
     * @return The Unicode locale type associated with the key, or null if the
     * locale does not define the key.
     * @throws IllegalArgumentException if the key is not well-formed
     * @throws NullPointerException if <code>key</code> is null
     * 
     * @stable ICU 4.4
     */
    public String getUnicodeLocaleType(String key) {
        if (!LocaleExtensions.isValidUnicodeLocaleKey(key)) {
            throw new IllegalArgumentException("Invalid Unicode locale key: " + key);
        }
        return extensions().getUnicodeLocaleType(key);
    }

    /**
     * Returns the set of Unicode locale keys defined by this locale, or the empty set if
     * this locale has none.  The returned set is immutable.  Keys are all lower case.
     *
     * @return The set of Unicode locale keys, or the empty set if this locale has
     * no Unicode locale keywords.
     * 
     * @stable ICU 4.4
     */
    public Set<String> getUnicodeLocaleKeys() {
        return extensions().getUnicodeLocaleKeys();
    }

    /**
     * Returns a well-formed IETF BCP 47 language tag representing
     * this locale.
     *
     * <p>If this <code>ULocale</code> has a language, script, country, or
     * variant that does not satisfy the IETF BCP 47 language tag
     * syntax requirements, this method handles these fields as
     * described below:
     *
     * <p><b>Language:</b> If language is empty, or not well-formed
     * (for example "a" or "e2"), it will be emitted as "und" (Undetermined).
     *
     * <p><b>Script:</b> If script is not well-formed (for example "12"
     * or "Latin"), it will be omitted.
     * 
     * <p><b>Country:</b> If country is not well-formed (for example "12"
     * or "USA"), it will be omitted.
     *
     * <p><b>Variant:</b> If variant <b>is</b> well-formed, each sub-segment
     * (delimited by '-' or '_') is emitted as a subtag.  Otherwise:
     * <ul>
     *
     * <li>if all sub-segments match <code>[0-9a-zA-Z]{1,8}</code>
     * (for example "WIN" or "Oracle_JDK_Standard_Edition"), the first
     * ill-formed sub-segment and all following will be appended to
     * the private use subtag.  The first appended subtag will be
     * "lvariant", followed by the sub-segments in order, separated by
     * hyphen. For example, "x-lvariant-WIN",
     * "Oracle-x-lvariant-JDK-Standard-Edition".
     *
     * <li>if any sub-segment does not match
     * <code>[0-9a-zA-Z]{1,8}</code>, the variant will be truncated
     * and the problematic sub-segment and all following sub-segments
     * will be omitted.  If the remainder is non-empty, it will be
     * emitted as a private use subtag as above (even if the remainder
     * turns out to be well-formed).  For example,
     * "Solaris_isjustthecoolestthing" is emitted as
     * "x-lvariant-Solaris", not as "solaris".</li></ul>
     *
     * <p><b>Note:</b> Although the language tag created by this
     * method is well-formed (satisfies the syntax requirements
     * defined by the IETF BCP 47 specification), it is not
     * necessarily a valid BCP 47 language tag.  For example,
     * <pre>
     *   new Locale("xx", "YY").toLanguageTag();</pre>
     * 
     * will return "xx-YY", but the language subtag "xx" and the
     * region subtag "YY" are invalid because they are not registered
     * in the IANA Language Subtag Registry.
     *
     * @return a BCP47 language tag representing the locale
     * @see #forLanguageTag(String)
     *
     * @stable ICU 4.2
     */
    public String toLanguageTag() {
        BaseLocale base = base();
        LocaleExtensions exts = extensions();

        if (base.getVariant().equalsIgnoreCase("POSIX")) {
            // special handling for variant POSIX
            base = BaseLocale.getInstance(base.getLanguage(), base.getScript(), base.getRegion(), "");
            if (exts.getUnicodeLocaleType("va") == null) {
                // add va-posix
                InternalLocaleBuilder ilocbld = new InternalLocaleBuilder();
                try {
                    ilocbld.setLocale(BaseLocale.ROOT, exts);
                    ilocbld.setUnicodeLocaleKeyword("va", "posix");
                    exts = ilocbld.getLocaleExtensions();
                } catch (LocaleSyntaxException e) {
                    // this should not happen
                    throw new RuntimeException(e);
                }
            }
        }

        LanguageTag tag = LanguageTag.parseLocale(base, exts);

        StringBuilder buf = new StringBuilder();
        String subtag = tag.getLanguage();
        if (subtag.length() > 0) {
            buf.append(LanguageTag.canonicalizeLanguage(subtag));
        }
 
        subtag = tag.getScript();
        if (subtag.length() > 0) {
            buf.append(LanguageTag.SEP);
            buf.append(LanguageTag.canonicalizeScript(subtag));
        }

        subtag = tag.getRegion();
        if (subtag.length() > 0) {
            buf.append(LanguageTag.SEP);
            buf.append(LanguageTag.canonicalizeRegion(subtag));
        }

        List<String>subtags = tag.getVariants();
        for (String s : subtags) {
            buf.append(LanguageTag.SEP);
            buf.append(LanguageTag.canonicalizeVariant(s));
        }

        subtags = tag.getExtensions();
        for (String s : subtags) {
            buf.append(LanguageTag.SEP);
            buf.append(LanguageTag.canonicalizeExtension(s));
        }

        subtag = tag.getPrivateuse();
        if (subtag.length() > 0) {
            if (buf.length() > 0) {
                buf.append(LanguageTag.SEP);
            }
            buf.append(LanguageTag.PRIVATEUSE).append(LanguageTag.SEP);
            buf.append(LanguageTag.canonicalizePrivateuse(subtag));
        }

        return buf.toString();
    }

    /**
     * Returns a locale for the specified IETF BCP 47 language tag string.
     *
     * <p>If the specified language tag contains any ill-formed subtags,
     * the first such subtag and all following subtags are ignored.  Compare
     * to {@link ULocale.Builder#setLanguageTag} which throws an exception
     * in this case.
     *
     * <p>The following <b>conversions</b> are performed:<ul>
     *
     * <li>The language code "und" is mapped to language "".
     *
     * <li>The portion of a private use subtag prefixed by "lvariant",
     * if any, is removed and appended to the variant field in the
     * result locale (without case normalization).  If it is then
     * empty, the private use subtag is discarded:
     *
     * <pre>
     *     ULocale loc;
     *     loc = ULocale.forLanguageTag("en-US-x-lvariant-icu4j);
     *     loc.getVariant(); // returns "ICU4J"
     *     loc.getExtension('x'); // returns null
     *
     *     loc = Locale.forLanguageTag("de-icu4j-x-URP-lvariant-Abc-Def");
     *     loc.getVariant(); // returns "ICU4J_ABC_DEF"
     *     loc.getExtension('x'); // returns "urp"
     * </pre>
     *
     * <li>When the languageTag argument contains an extlang subtag,
     * the first such subtag is used as the language, and the primary
     * language subtag and other extlang subtags are ignored:
     *
     * <pre>
     *     ULocale.forLanguageTag("ar-aao").getLanguage(); // returns "aao"
     *     ULocale.forLanguageTag("en-abc-def-us").toString(); // returns "abc_US"
     * </pre>
     *
     * <li>Case is normalized. Language is normalized to lower case,
     * script to title case, country to upper case, variant to upper case,
     * and extensions to lower case.
     *
     * <p>This implements the 'Language-Tag' production of BCP47, and
     * so supports grandfathered (regular and irregular) as well as
     * private use language tags.  Stand alone private use tags are
     * represented as empty language and extension 'x-whatever',
     * and grandfathered tags are converted to their canonical replacements
     * where they exist.  
     *
     * <p>Grandfathered tags with canonical replacements are as follows:
     *
     * <table>
     * <tbody align="center">
     * <tr><th>grandfathered tag</th><th>&nbsp;</th><th>modern replacement</th></tr>
     * <tr><td>art-lojban</td><td>&nbsp;</td><td>jbo</td></tr>
     * <tr><td>i-ami</td><td>&nbsp;</td><td>ami</td></tr>
     * <tr><td>i-bnn</td><td>&nbsp;</td><td>bnn</td></tr>
     * <tr><td>i-hak</td><td>&nbsp;</td><td>hak</td></tr>
     * <tr><td>i-klingon</td><td>&nbsp;</td><td>tlh</td></tr>
     * <tr><td>i-lux</td><td>&nbsp;</td><td>lb</td></tr>
     * <tr><td>i-navajo</td><td>&nbsp;</td><td>nv</td></tr>
     * <tr><td>i-pwn</td><td>&nbsp;</td><td>pwn</td></tr>
     * <tr><td>i-tao</td><td>&nbsp;</td><td>tao</td></tr>
     * <tr><td>i-tay</td><td>&nbsp;</td><td>tay</td></tr>
     * <tr><td>i-tsu</td><td>&nbsp;</td><td>tsu</td></tr>
     * <tr><td>no-bok</td><td>&nbsp;</td><td>nb</td></tr>
     * <tr><td>no-nyn</td><td>&nbsp;</td><td>nn</td></tr>
     * <tr><td>sgn-BE-FR</td><td>&nbsp;</td><td>sfb</td></tr>
     * <tr><td>sgn-BE-NL</td><td>&nbsp;</td><td>vgt</td></tr>
     * <tr><td>sgn-CH-DE</td><td>&nbsp;</td><td>sgg</td></tr>
     * <tr><td>zh-guoyu</td><td>&nbsp;</td><td>cmn</td></tr>
     * <tr><td>zh-hakka</td><td>&nbsp;</td><td>hak</td></tr>
     * <tr><td>zh-min-nan</td><td>&nbsp;</td><td>nan</td></tr>
     * <tr><td>zh-xiang</td><td>&nbsp;</td><td>hsn</td></tr>
     * </tbody>
     * </table>
     *
     * <p>Grandfathered tags with no modern replacement will be
     * converted as follows:
     *
     * <table>
     * <tbody align="center">
     * <tr><th>grandfathered tag</th><th>&nbsp;</th><th>converts to</th></tr>
     * <tr><td>cel-gaulish</td><td>&nbsp;</td><td>xtg-x-cel-gaulish</td></tr>
     * <tr><td>en-GB-oed</td><td>&nbsp;</td><td>en-GB-x-oed</td></tr>
     * <tr><td>i-default</td><td>&nbsp;</td><td>en-x-i-default</td></tr>
     * <tr><td>i-enochian</td><td>&nbsp;</td><td>und-x-i-enochian</td></tr>
     * <tr><td>i-mingo</td><td>&nbsp;</td><td>see-x-i-mingo</td></tr>
     * <tr><td>zh-min</td><td>&nbsp;</td><td>nan-x-zh-min</td></tr>
     * </tbody>
     * </table>
     *
     * <p>For a list of all grandfathered tags, see the
     * IANA Language Subtag Registry (search for "Type: grandfathered").
     *
     * <p><b>Note</b>: there is no guarantee that <code>toLanguageTag</code>
     * and <code>forLanguageTag</code> will round-trip.
     *
     * @param languageTag the language tag
     * @return The locale that best represents the language tag.
     * @throws NullPointerException if <code>languageTag</code> is <code>null</code>
     * @see #toLanguageTag()
     * @see ULocale.Builder#setLanguageTag(String)
     *
     * @stable ICU 4.2
     */
    public static ULocale forLanguageTag(String languageTag) {
        LanguageTag tag = LanguageTag.parse(languageTag, null);
        InternalLocaleBuilder bldr = new InternalLocaleBuilder();
        bldr.setLanguageTag(tag);
        return getInstance(bldr.getBaseLocale(), bldr.getLocaleExtensions());
    }

    /**
     * {@icu} Converts the specified keyword (legacy key, or BCP 47 Unicode locale
     * extension key) to the equivalent BCP 47 Unicode locale extension key.
     * For example, BCP 47 Unicode locale extension key "co" is returned for
     * the input keyword "collation".
     * <p>
     * When the specified keyword is unknown, but satisfies the BCP syntax,
     * then the lower-case version of the input keyword will be returned.
     * For example,
     * <code>toUnicodeLocaleKey("ZZ")</code> returns "zz".
     * 
     * @param keyword       the input locale keyword (either legacy key
     *                      such as "collation" or BCP 47 Unicode locale extension
     *                      key such as "co").
     * @return              the well-formed BCP 47 Unicode locale extension key,
     *                      or null if the specified locale keyword cannot be mapped
     *                      to a well-formed BCP 47 Unicode locale extension key. 
     * @see #toLegacyKey(String)
     * @draft ICU 54
     * @provisional This API might change or be removed in a future release.
     */
    public static String toUnicodeLocaleKey(String keyword) {
        String bcpKey = KeyTypeData.toBcpKey(keyword);
        if (bcpKey == null && UnicodeLocaleExtension.isKey(keyword)) {
            // unknown keyword, but syntax is fine..
            bcpKey = AsciiUtil.toLowerString(keyword);
        }
        return bcpKey;
    }

    /**
     * {@icu} Converts the specified keyword value (legacy type, or BCP 47
     * Unicode locale extension type) to the well-formed BCP 47 Unicode locale
     * extension type for the specified keyword (category). For example, BCP 47
     * Unicode locale extension type "phonebk" is returned for the input
     * keyword value "phonebook", with the keyword "collation" (or "co").
     * <p>
     * When the specified keyword is not recognized, but the specified value
     * satisfies the syntax of the BCP 47 Unicode locale extension type,
     * or when the specified keyword allows 'variable' type and the specified
     * value satisfies the syntax, the lower-case version of the input value
     * will be returned. For example,
     * <code>toUnicodeLocaleType("Foo", "Bar")</code> returns "bar",
     * <code>toUnicodeLocaleType("variableTop", "00A4")</code> returns "00a4".
     * 
     * @param keyword       the locale keyword (either legacy key such as
     *                      "collation" or BCP 47 Unicode locale extension
     *                      key such as "co").
     * @param value         the locale keyword value (either legacy type
     *                      such as "phonebook" or BCP 47 Unicode locale extension
     *                      type such as "phonebk").
     * @return              the well-formed BCP47 Unicode locale extension type,
     *                      or null if the locale keyword value cannot be mapped to
     *                      a well-formed BCP 47 Unicode locale extension type.
     * @see #toLegacyType(String, String)
     * @draft ICU 54
     * @provisional This API might change or be removed in a future release.
     */
    public static String toUnicodeLocaleType(String keyword, String value) {
        String bcpType = KeyTypeData.toBcpType(keyword, value, null, null);
        if (bcpType == null && UnicodeLocaleExtension.isType(value)) {
            // unknown keyword, but syntax is fine..
            bcpType = AsciiUtil.toLowerString(value);
        }
        return bcpType;
    }

    /**
     * {@icu} Converts the specified keyword (BCP 47 Unicode locale extension key, or
     * legacy key) to the legacy key. For example, legacy key "collation" is
     * returned for the input BCP 47 Unicode locale extension key "co".
     * 
     * @param keyword       the input locale keyword (either BCP 47 Unicode locale
     *                      extension key or legacy key).
     * @return              the well-formed legacy key, or null if the specified
     *                      keyword cannot be mapped to a well-formed legacy key.
     * @see #toUnicodeLocaleKey(String)
     * @draft ICU 54
     * @provisional This API might change or be removed in a future release.
     */
    public static String toLegacyKey(String keyword) {
        String legacyKey = KeyTypeData.toLegacyKey(keyword);
        if (legacyKey == null) {
            // Checks if the specified locale key is well-formed with the legacy locale syntax.
            //
            // Note:
            //  Neither ICU nor LDML/CLDR provides the definition of keyword syntax.
            //  However, a key should not contain '=' obviously. For now, all existing
            //  keys are using ASCII alphabetic letters only. We won't add any new key
            //  that is not compatible with the BCP 47 syntax. Therefore, we assume
            //  a valid key consist from [0-9a-zA-Z], no symbols.
            if (keyword.matches("[0-9a-zA-Z]+")) {
                legacyKey = AsciiUtil.toLowerString(keyword);
            }
        }
        return legacyKey;
    }

    /**
     * {@icu} Converts the specified keyword value (BCP 47 Unicode locale extension type,
     * or legacy type or type alias) to the canonical legacy type. For example,
     * the legacy type "phonebook" is returned for the input BCP 47 Unicode
     * locale extension type "phonebk" with the keyword "collation" (or "co").
     * <p>
     * When the specified keyword is not recognized, but the specified value
     * satisfies the syntax of legacy key, or when the specified keyword
     * allows 'variable' type and the specified value satisfies the syntax,
     * the lower-case version of the input value will be returned.
     * For example,
     * <code>toLegacyType("Foo", "Bar")</code> returns "bar",
     * <code>toLegacyType("vt", "00A4")</code> returns "00a4".
     *
     * @param keyword       the locale keyword (either legacy keyword such as
     *                      "collation" or BCP 47 Unicode locale extension
     *                      key such as "co").
     * @param value         the locale keyword value (either BCP 47 Unicode locale
     *                      extension type such as "phonebk" or legacy keyword value
     *                      such as "phonebook").
     * @return              the well-formed legacy type, or null if the specified
     *                      keyword value cannot be mapped to a well-formed legacy
     *                      type.
     * @see #toUnicodeLocaleType(String, String)
     * @draft ICU 54
     * @provisional This API might change or be removed in a future release.
     */
    public static String toLegacyType(String keyword, String value) {
        String legacyType = KeyTypeData.toLegacyType(keyword, value, null, null);
        if (legacyType == null) {
            // Checks if the specified locale type is well-formed with the legacy locale syntax.
            //
            // Note:
            //  Neither ICU nor LDML/CLDR provides the definition of keyword syntax.
            //  However, a type should not contain '=' obviously. For now, all existing
            //  types are using ASCII alphabetic letters with a few symbol letters. We won't
            //  add any new type that is not compatible with the BCP 47 syntax except timezone
            //  IDs. For now, we assume a valid type start with [0-9a-zA-Z], but may contain
            //  '-' '_' '/' in the middle.
            if (value.matches("[0-9a-zA-Z]+([_/\\-][0-9a-zA-Z]+)*")) {
                legacyType = AsciiUtil.toLowerString(value);
            }
        }
        return legacyType;
    }

    /**
     * <code>Builder</code> is used to build instances of <code>ULocale</code>
     * from values configured by the setters.  Unlike the <code>ULocale</code>
     * constructors, the <code>Builder</code> checks if a value configured by a
     * setter satisfies the syntax requirements defined by the <code>ULocale</code>
     * class.  A <code>ULocale</code> object created by a <code>Builder</code> is
     * well-formed and can be transformed to a well-formed IETF BCP 47 language tag
     * without losing information.
     *
     * <p><b>Note:</b> The <code>ULocale</code> class does not provide any
     * syntactic restrictions on variant, while BCP 47 requires each variant
     * subtag to be 5 to 8 alphanumerics or a single numeric followed by 3
     * alphanumerics.  The method <code>setVariant</code> throws
     * <code>IllformedLocaleException</code> for a variant that does not satisfy
     * this restriction. If it is necessary to support such a variant, use a
     * ULocale constructor.  However, keep in mind that a <code>ULocale</code>
     * object created this way might lose the variant information when
     * transformed to a BCP 47 language tag.
     *
     * <p>The following example shows how to create a <code>Locale</code> object
     * with the <code>Builder</code>.
     * <blockquote>
     * <pre>
     *     ULocale aLocale = new Builder().setLanguage("sr").setScript("Latn").setRegion("RS").build();
     * </pre>
     * </blockquote>
     *
     * <p>Builders can be reused; <code>clear()</code> resets all
     * fields to their default values.
     *
     * @see ULocale#toLanguageTag()
     *
     * @stable ICU 4.2
     */
    public static final class Builder {

        private final InternalLocaleBuilder _locbld;

        /**
         * Constructs an empty Builder. The default value of all
         * fields, extensions, and private use information is the
         * empty string.
         *
         * @stable ICU 4.2
         */
        public Builder() {
            _locbld = new InternalLocaleBuilder();
        }

        /**
         * Resets the <code>Builder</code> to match the provided
         * <code>locale</code>.  Existing state is discarded.
         *
         * <p>All fields of the locale must be well-formed, see {@link Locale}.
         *
         * <p>Locales with any ill-formed fields cause
         * <code>IllformedLocaleException</code> to be thrown.
         *
         * @param locale the locale
         * @return This builder.
         * @throws IllformedLocaleException if <code>locale</code> has
         * any ill-formed fields.
         * @throws NullPointerException if <code>locale</code> is null.
         *
         * @stable ICU 4.2
         */
        public Builder setLocale(ULocale locale) {
            try {
                _locbld.setLocale(locale.base(), locale.extensions());
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Resets the Builder to match the provided IETF BCP 47
         * language tag.  Discards the existing state.  Null and the
         * empty string cause the builder to be reset, like {@link
         * #clear}.  Grandfathered tags (see {@link
         * ULocale#forLanguageTag}) are converted to their canonical
         * form before being processed.  Otherwise, the language tag
         * must be well-formed (see {@link ULocale}) or an exception is
         * thrown (unlike <code>ULocale.forLanguageTag</code>, which
         * just discards ill-formed and following portions of the
         * tag).
         *
         * @param languageTag the language tag
         * @return This builder.
         * @throws IllformedLocaleException if <code>languageTag</code> is ill-formed
         * @see ULocale#forLanguageTag(String)
         *
         * @stable ICU 4.2
         */
        public Builder setLanguageTag(String languageTag) {
            ParseStatus sts = new ParseStatus();
            LanguageTag tag = LanguageTag.parse(languageTag, sts);
            if (sts.isError()) {
                throw new IllformedLocaleException(sts.getErrorMessage(), sts.getErrorIndex());
            }
            _locbld.setLanguageTag(tag);

            return this;
        }

        /**
         * Sets the language.  If <code>language</code> is the empty string or
         * null, the language in this <code>Builder</code> is removed.  Otherwise,
         * the language must be <a href="./Locale.html#def_language">well-formed</a>
         * or an exception is thrown.
         *
         * <p>The typical language value is a two or three-letter language
         * code as defined in ISO639.
         *
         * @param language the language
         * @return This builder.
         * @throws IllformedLocaleException if <code>language</code> is ill-formed
         *
         * @stable ICU 4.2
         */
        public Builder setLanguage(String language) {
            try {
                _locbld.setLanguage(language);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Sets the script. If <code>script</code> is null or the empty string,
         * the script in this <code>Builder</code> is removed.
         * Otherwise, the script must be well-formed or an exception is thrown.
         *
         * <p>The typical script value is a four-letter script code as defined by ISO 15924.
         *
         * @param script the script
         * @return This builder.
         * @throws IllformedLocaleException if <code>script</code> is ill-formed
         *
         * @stable ICU 4.2
         */
        public Builder setScript(String script) {
            try {
                _locbld.setScript(script);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Sets the region.  If region is null or the empty string, the region
         * in this <code>Builder</code> is removed.  Otherwise,
         * the region must be well-formed or an exception is thrown.
         *
         * <p>The typical region value is a two-letter ISO 3166 code or a
         * three-digit UN M.49 area code.
         *
         * <p>The country value in the <code>Locale</code> created by the
         * <code>Builder</code> is always normalized to upper case.
         *
         * @param region the region
         * @return This builder.
         * @throws IllformedLocaleException if <code>region</code> is ill-formed
         *
         * @stable ICU 4.2
         */
        public Builder setRegion(String region) {
            try {
                _locbld.setRegion(region);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Sets the variant.  If variant is null or the empty string, the
         * variant in this <code>Builder</code> is removed.  Otherwise, it
         * must consist of one or more well-formed subtags, or an exception is thrown.
         *
         * <p><b>Note:</b> This method checks if <code>variant</code>
         * satisfies the IETF BCP 47 variant subtag's syntax requirements,
         * and normalizes the value to lowercase letters.  However,
         * the <code>ULocale</code> class does not impose any syntactic
         * restriction on variant.  To set such a variant,
         * use a ULocale constructor.
         *
         * @param variant the variant
         * @return This builder.
         * @throws IllformedLocaleException if <code>variant</code> is ill-formed
         *
         * @stable ICU 4.2
         */
        public Builder setVariant(String variant) {
            try {
                _locbld.setVariant(variant);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Sets the extension for the given key. If the value is null or the
         * empty string, the extension is removed.  Otherwise, the extension
         * must be well-formed or an exception is thrown.
         *
         * <p><b>Note:</b> The key {@link ULocale#UNICODE_LOCALE_EXTENSION
         * UNICODE_LOCALE_EXTENSION} ('u') is used for the Unicode locale extension.
         * Setting a value for this key replaces any existing Unicode locale key/type
         * pairs with those defined in the extension.
         *
         * <p><b>Note:</b> The key {@link ULocale#PRIVATE_USE_EXTENSION
         * PRIVATE_USE_EXTENSION} ('x') is used for the private use code. To be
         * well-formed, the value for this key needs only to have subtags of one to
         * eight alphanumeric characters, not two to eight as in the general case.
         *
         * @param key the extension key
         * @param value the extension value
         * @return This builder.
         * @throws IllformedLocaleException if <code>key</code> is illegal
         * or <code>value</code> is ill-formed
         * @see #setUnicodeLocaleKeyword(String, String)
         *
         * @stable ICU 4.2
         */
        public Builder setExtension(char key, String value) {
            try {
                _locbld.setExtension(key, value);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Sets the Unicode locale keyword type for the given key.  If the type
         * is null, the Unicode keyword is removed.  Otherwise, the key must be
         * non-null and both key and type must be well-formed or an exception
         * is thrown.
         *
         * <p>Keys and types are converted to lower case.
         *
         * <p><b>Note</b>:Setting the 'u' extension via {@link #setExtension}
         * replaces all Unicode locale keywords with those defined in the
         * extension.
         *
         * @param key the Unicode locale key
         * @param type the Unicode locale type
         * @return This builder.
         * @throws IllformedLocaleException if <code>key</code> or <code>type</code>
         * is ill-formed
         * @throws NullPointerException if <code>key</code> is null
         * @see #setExtension(char, String)
         *
         * @stable ICU 4.4
         */
        public Builder setUnicodeLocaleKeyword(String key, String type) {
            try {
                _locbld.setUnicodeLocaleKeyword(key, type);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Adds a unicode locale attribute, if not already present, otherwise
         * has no effect.  The attribute must not be null and must be well-formed
         * or an exception is thrown.
         *
         * @param attribute the attribute
         * @return This builder.
         * @throws NullPointerException if <code>attribute</code> is null
         * @throws IllformedLocaleException if <code>attribute</code> is ill-formed
         * @see #setExtension(char, String)
         *
         * @stable ICU 4.6
         */
        public Builder addUnicodeLocaleAttribute(String attribute) {
            try {
                _locbld.addUnicodeLocaleAttribute(attribute);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Removes a unicode locale attribute, if present, otherwise has no
         * effect.  The attribute must not be null and must be well-formed
         * or an exception is thrown.
         *
         * <p>Attribute comparision for removal is case-insensitive.
         *
         * @param attribute the attribute
         * @return This builder.
         * @throws NullPointerException if <code>attribute</code> is null
         * @throws IllformedLocaleException if <code>attribute</code> is ill-formed
         * @see #setExtension(char, String)
         *
         * @stable ICU 4.6
         */
        public Builder removeUnicodeLocaleAttribute(String attribute) {
            try {
                _locbld.removeUnicodeLocaleAttribute(attribute);
            } catch (LocaleSyntaxException e) {
                throw new IllformedLocaleException(e.getMessage(), e.getErrorIndex());
            }
            return this;
        }

        /**
         * Resets the builder to its initial, empty state.
         *
         * @return this builder
         *
         * @stable ICU 4.2
         */
        public Builder clear() {
            _locbld.clear();
            return this;
        }

        /**
         * Resets the extensions to their initial, empty state.
         * Language, script, region and variant are unchanged.
         *
         * @return this builder
         * @see #setExtension(char, String)
         *
         * @stable ICU 4.2
         */
        public Builder clearExtensions() {
            _locbld.clearExtensions();
            return this;
        }

        /**
         * Returns an instance of <code>ULocale</code> created from the fields set
         * on this builder.
         *
         * @return a new Locale
         *
         * @stable ICU 4.4
         */
        public ULocale build() {
            return getInstance(_locbld.getBaseLocale(), _locbld.getLocaleExtensions());
        }
    }

    private static ULocale getInstance(BaseLocale base, LocaleExtensions exts) {
        String id = lscvToID(base.getLanguage(), base.getScript(), base.getRegion(),
                base.getVariant());

        Set<Character> extKeys = exts.getKeys();
        if (!extKeys.isEmpty()) {
            // legacy locale ID assume Unicode locale keywords and
            // other extensions are at the same level.
            // e.g. @a=ext-for-aa;calendar=japanese;m=ext-for-mm;x=priv-use

            TreeMap<String, String> kwds = new TreeMap<String, String>();
            for (Character key : extKeys) {
                Extension ext = exts.getExtension(key);
                if (ext instanceof UnicodeLocaleExtension) {
                    UnicodeLocaleExtension uext = (UnicodeLocaleExtension)ext;
                    Set<String> ukeys = uext.getUnicodeLocaleKeys();
                    for (String bcpKey : ukeys) {
                        String bcpType = uext.getUnicodeLocaleType(bcpKey);
                        // convert to legacy key/type
                        String lkey = toLegacyKey(bcpKey);
                        String ltype = toLegacyType(bcpKey, ((bcpType.length() == 0) ? "yes" : bcpType)); // use "yes" as the value of typeless keywords
                        // special handling for u-va-posix, since this is a variant, not a keyword
                        if (lkey.equals("va") && ltype.equals("posix") && base.getVariant().length() == 0) {
                            id = id + "_POSIX";
                        } else {
                            kwds.put(lkey, ltype);
                        }
                    }
                    // Mapping Unicode locale attribute to the special keyword, attribute=xxx-yyy
                    Set<String> uattributes = uext.getUnicodeLocaleAttributes();
                    if (uattributes.size() > 0) {
                        StringBuilder attrbuf = new StringBuilder();
                        for (String attr : uattributes) {
                            if (attrbuf.length() > 0) {
                                attrbuf.append('-');
                            }
                            attrbuf.append(attr);
                        }
                        kwds.put(LOCALE_ATTRIBUTE_KEY, attrbuf.toString());
                    }
                } else {
                    kwds.put(String.valueOf(key), ext.getValue());
                }
            }

            if (!kwds.isEmpty()) {
                StringBuilder buf = new StringBuilder(id);
                buf.append("@");
                Set<Map.Entry<String, String>> kset = kwds.entrySet();
                boolean insertSep = false;
                for (Map.Entry<String, String> kwd : kset) {
                    if (insertSep) {
                        buf.append(";");
                    } else {
                        insertSep = true;
                    }
                    buf.append(kwd.getKey());
                    buf.append("=");
                    buf.append(kwd.getValue());
                }

                id = buf.toString();
            }
        }
        return new ULocale(id);
    }

    private BaseLocale base() {
        if (baseLocale == null) {
            String language, script, region, variant;
            language = script = region = variant = "";
            if (!equals(ULocale.ROOT)) {
                LocaleIDParser lp = new LocaleIDParser(localeID);
                language = lp.getLanguage();
                script = lp.getScript();
                region = lp.getCountry();
                variant = lp.getVariant();
            }
            baseLocale = BaseLocale.getInstance(language, script, region, variant);
        }
        return baseLocale;
    }

    private LocaleExtensions extensions() {
        if (extensions == null) {
            Iterator<String> kwitr = getKeywords();
            if (kwitr == null) {
                extensions = LocaleExtensions.EMPTY_EXTENSIONS;
            } else {
                InternalLocaleBuilder intbld = new InternalLocaleBuilder();
                while (kwitr.hasNext()) {
                    String key = kwitr.next();
                    if (key.equals(LOCALE_ATTRIBUTE_KEY)) {
                        // special keyword used for representing Unicode locale attributes
                        String[] uattributes = getKeywordValue(key).split("[-_]");
                        for (String uattr : uattributes) {
                            try {
                                intbld.addUnicodeLocaleAttribute(uattr);
                            } catch (LocaleSyntaxException e) {
                                // ignore and fall through
                            }
                        }
                    } else if (key.length() >= 2) {
                        String bcpKey = toUnicodeLocaleKey(key);
                        String bcpType = toUnicodeLocaleType(key, getKeywordValue(key));
                        if (bcpKey != null && bcpType != null) {
                            try {
                                intbld.setUnicodeLocaleKeyword(bcpKey, bcpType);
                            } catch (LocaleSyntaxException e) {
                                // ignore and fall through
                            }
                        }
                    } else if (key.length() == 1 && (key.charAt(0) != UNICODE_LOCALE_EXTENSION)) {
                        try  {
                            intbld.setExtension(key.charAt(0), getKeywordValue(key).replace("_",
                                    LanguageTag.SEP));
                        } catch (LocaleSyntaxException e) {
                            // ignore and fall through
                        }
                    }
                }
                extensions = intbld.getLocaleExtensions();
            }
        }
        return extensions;
    }

    /*
     * JDK Locale Helper
     */
    private static final class JDKLocaleHelper {
        private static boolean isJava7orNewer = false;

        /*
         * New methods in Java 7 Locale class
         */
        private static Method mGetScript;
        private static Method mGetExtensionKeys;
        private static Method mGetExtension;
        private static Method mGetUnicodeLocaleKeys;
        private static Method mGetUnicodeLocaleAttributes;
        private static Method mGetUnicodeLocaleType;
        private static Method mForLanguageTag;

        private static Method mGetDefault;
        private static Method mSetDefault;
        private static Object eDISPLAY;
        private static Object eFORMAT;

        /*
         * This table is used for mapping between ICU and special Java
         * 6 locales.  When an ICU locale matches <minumum base> with
         * <keyword>/<value>, the ICU locale is mapped to <Java> locale.
         * For example, both ja_JP@calendar=japanese and ja@calendar=japanese
         * are mapped to Java locale "ja_JP_JP".  ICU locale "nn" is mapped
         * to Java locale "no_NO_NY".
         */
        private static final String[][] JAVA6_MAPDATA = {
        //  { <Java>,       <ICU base>, <keyword>,  <value>,    <minimum base>
            { "ja_JP_JP",   "ja_JP",    "calendar", "japanese", "ja"},
            { "no_NO_NY",   "nn_NO",    null,       null,       "nn"},
            { "th_TH_TH",   "th_TH",    "numbers",  "thai",     "th"},
        };

        static {
            do {
                try {
                    mGetScript = Locale.class.getMethod("getScript", (Class[]) null);
                    mGetExtensionKeys = Locale.class.getMethod("getExtensionKeys", (Class[]) null);
                    mGetExtension = Locale.class.getMethod("getExtension", char.class);
                    mGetUnicodeLocaleKeys = Locale.class.getMethod("getUnicodeLocaleKeys", (Class[]) null);
                    mGetUnicodeLocaleAttributes = Locale.class.getMethod("getUnicodeLocaleAttributes", (Class[]) null);
                    mGetUnicodeLocaleType = Locale.class.getMethod("getUnicodeLocaleType", String.class);
                    mForLanguageTag = Locale.class.getMethod("forLanguageTag", String.class);
    
                    Class<?> cCategory = null;
                    Class<?>[] classes = Locale.class.getDeclaredClasses();
                    for (Class<?> c : classes) {
                        if (c.getName().equals("java.util.Locale$Category")) {
                            cCategory = c;
                            break;
                        }
                    }
                    if (cCategory == null) {
                        break;
                    }
                    mGetDefault = Locale.class.getDeclaredMethod("getDefault", cCategory);
                    mSetDefault = Locale.class.getDeclaredMethod("setDefault", cCategory, Locale.class);
    
                    Method mName = cCategory.getMethod("name", (Class[]) null);
                    Object[] enumConstants = cCategory.getEnumConstants();
                    for (Object e : enumConstants) {
                        String catVal = (String)mName.invoke(e, (Object[])null);
                        if (catVal.equals("DISPLAY")) {
                            eDISPLAY = e;
                        } else if (catVal.equals("FORMAT")) {
                            eFORMAT = e;
                        }
                    }
                    if (eDISPLAY == null || eFORMAT == null) {
                        break;
                    }    
                    isJava7orNewer = true;
                } catch (NoSuchMethodException e) {
                } catch (IllegalArgumentException e) {
                } catch (IllegalAccessException e) {
                } catch (InvocationTargetException e) {
                } catch (SecurityException e) {
                    // TODO : report?
                }
            } while (false);
        }

        private JDKLocaleHelper() {
        }

        public static boolean isJava7orNewer() {
            return isJava7orNewer;
        }

        public static ULocale toULocale(Locale loc) {
            return isJava7orNewer ? toULocale7(loc) : toULocale6(loc);
        }

        public static Locale toLocale(ULocale uloc) {
            return isJava7orNewer ? toLocale7(uloc) : toLocale6(uloc);
        }

        private static ULocale toULocale7(Locale loc) {
            String language = loc.getLanguage();
            String script = "";
            String country = loc.getCountry();
            String variant = loc.getVariant();

            Set<String> attributes = null;
            Map<String, String> keywords = null;

            try {
                script = (String) mGetScript.invoke(loc, (Object[]) null);
                @SuppressWarnings("unchecked")
                Set<Character> extKeys = (Set<Character>) mGetExtensionKeys.invoke(loc, (Object[]) null);
                if (!extKeys.isEmpty()) {
                    for (Character extKey : extKeys) {
                        if (extKey.charValue() == 'u') {
                            // Found Unicode locale extension

                            // attributes
                            @SuppressWarnings("unchecked")
                            Set<String> uAttributes = (Set<String>) mGetUnicodeLocaleAttributes.invoke(loc, (Object[]) null);
                            if (!uAttributes.isEmpty()) {
                                attributes = new TreeSet<String>();
                                for (String attr : uAttributes) {
                                    attributes.add(attr);
                                }
                            }

                            // keywords
                            @SuppressWarnings("unchecked")
                            Set<String> uKeys = (Set<String>) mGetUnicodeLocaleKeys.invoke(loc, (Object[]) null);
                            for (String kwKey : uKeys) {
                                String kwVal = (String) mGetUnicodeLocaleType.invoke(loc, kwKey);
                                if (kwVal != null) {
                                    if (kwKey.equals("va")) {
                                        // va-* is interpreted as a variant
                                        variant = (variant.length() == 0) ? kwVal : kwVal + "_" + variant;
                                    } else {
                                        if (keywords == null) {
                                            keywords = new TreeMap<String, String>();
                                        }
                                        keywords.put(kwKey, kwVal);
                                    }
                                }
                            }
                        } else {
                            String extVal = (String) mGetExtension.invoke(loc, extKey);
                            if (extVal != null) {
                                if (keywords == null) {
                                    keywords = new TreeMap<String, String>();
                                }
                                keywords.put(String.valueOf(extKey), extVal);
                            }
                        }
                    }
                }
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            } catch (InvocationTargetException e) {
                throw new RuntimeException(e);
            }

            // JDK locale no_NO_NY is not interpreted as Nynorsk by ICU,
            // and it should be transformed to nn_NO.

            // Note: JDK7+ unerstand both no_NO_NY and nn_NO. When convert
            // ICU locale to JDK, we do not need to map nn_NO back to no_NO_NY.

            if (language.equals("no") && country.equals("NO") && variant.equals("NY")) {
                language = "nn";
                variant = "";
            }

            // Constructing ID
            StringBuilder buf = new StringBuilder(language);

            if (script.length() > 0) {
                buf.append('_');
                buf.append(script);
            }

            if (country.length() > 0) {
                buf.append('_');
                buf.append(country);
            }

            if (variant.length() > 0) {
                if (country.length() == 0) {
                    buf.append('_');
                }
                buf.append('_');
                buf.append(variant);
            }

            if (attributes != null) {
                // transform Unicode attributes into a keyword
                StringBuilder attrBuf = new StringBuilder();
                for (String attr : attributes) {
                    if (attrBuf.length() != 0) {
                        attrBuf.append('-');
                    }
                    attrBuf.append(attr);
                }
                if (keywords == null) {
                    keywords = new TreeMap<String, String>();
                }
                keywords.put(LOCALE_ATTRIBUTE_KEY, attrBuf.toString());
            }

            if (keywords != null) {
                buf.append('@');
                boolean addSep = false;
                for (Entry<String, String> kwEntry : keywords.entrySet()) {
                    String kwKey = kwEntry.getKey();
                    String kwVal = kwEntry.getValue();

                    if (kwKey.length() != 1) {
                        // Unicode locale key
                        kwKey = toLegacyKey(kwKey);
                        // use "yes" as the value of typeless keywords
                        kwVal = toLegacyType(kwKey, ((kwVal.length() == 0) ? "yes" : kwVal));
                    }

                    if (addSep) {
                        buf.append(';');
                    } else {
                        addSep = true;
                    }
                    buf.append(kwKey);
                    buf.append('=');
                    buf.append(kwVal);
                }
            }

            return new ULocale(getName(buf.toString()), loc);
        }

        private static ULocale toULocale6(Locale loc) {
            ULocale uloc = null;
            String locStr = loc.toString();
            if (locStr.length() == 0) {
                uloc = ULocale.ROOT;
            } else {
                for (int i = 0; i < JAVA6_MAPDATA.length; i++) {
                    if (JAVA6_MAPDATA[i][0].equals(locStr)) {
                        LocaleIDParser p = new LocaleIDParser(JAVA6_MAPDATA[i][1]);
                        p.setKeywordValue(JAVA6_MAPDATA[i][2], JAVA6_MAPDATA[i][3]);
                        locStr = p.getName();
                        break;
                    }
                }
                uloc = new ULocale(getName(locStr), loc);
            }
            return uloc;
        }

        private static Locale toLocale7(ULocale uloc) {
            Locale loc = null;
            String ulocStr = uloc.getName();
            if (uloc.getScript().length() > 0 || ulocStr.contains("@")) {
                // With script or keywords available, the best way
                // to get a mapped Locale is to go through a language tag.
                // A Locale with script or keywords can only have variants
                // that is 1 to 8 alphanum. If this ULocale has a variant
                // subtag not satisfying the criteria, the variant subtag
                // will be lost.
                String tag = uloc.toLanguageTag();

                // Workaround for variant casing problem:
                //
                // The variant field in ICU is case insensitive and normalized
                // to upper case letters by getVariant(), while
                // the variant field in JDK Locale is case sensitive.
                // ULocale#toLanguageTag use lower case characters for
                // BCP 47 variant and private use x-lvariant.
                //
                // Locale#forLanguageTag in JDK preserves character casing
                // for variant. Because ICU always normalizes variant to
                // upper case, we convert language tag to upper case here.
                tag = AsciiUtil.toUpperString(tag);

                try {
                    loc = (Locale)mForLanguageTag.invoke(null, tag);
                } catch (IllegalAccessException e) {
                    throw new RuntimeException(e);
                } catch (InvocationTargetException e) {
                    throw new RuntimeException(e);
                }
            }
            if (loc == null) {
                // Without script or keywords, use a Locale constructor,
                // so we can preserve any ill-formed variants.
                loc = new Locale(uloc.getLanguage(), uloc.getCountry(), uloc.getVariant());
            }
            return loc;
        }

        private static Locale toLocale6(ULocale uloc) {
            String locstr = uloc.getBaseName();
            for (int i = 0; i < JAVA6_MAPDATA.length; i++) {
                if (locstr.equals(JAVA6_MAPDATA[i][1]) || locstr.equals(JAVA6_MAPDATA[i][4])) {
                    if (JAVA6_MAPDATA[i][2] != null) {
                        String val = uloc.getKeywordValue(JAVA6_MAPDATA[i][2]);
                        if (val != null && val.equals(JAVA6_MAPDATA[i][3])) {
                            locstr = JAVA6_MAPDATA[i][0];
                            break;
                        }
                    } else {
                        locstr = JAVA6_MAPDATA[i][0];
                        break;
                    }
                }
            }
            LocaleIDParser p = new LocaleIDParser(locstr);
            String[] names = p.getLanguageScriptCountryVariant();
            return new Locale(names[0], names[2], names[3]);
        }

        public static Locale getDefault(Category category) {
            Locale loc = Locale.getDefault();
            if (isJava7orNewer) {
                Object cat = null;
                switch (category) {
                case DISPLAY:
                    cat = eDISPLAY;
                    break;
                case FORMAT:
                    cat = eFORMAT;
                    break;
                }
                if (cat != null) {
                    try {
                        loc = (Locale)mGetDefault.invoke(null, cat);
                    } catch (InvocationTargetException e) {
                        // fall through - use the base default
                    } catch (IllegalArgumentException e) {
                        // fall through - use the base default
                    } catch (IllegalAccessException e) {
                        // fall through - use the base default
                    }
                }
            }
            return loc;
        }

        public static void setDefault(Category category, Locale newLocale) {
            if (isJava7orNewer) {
                Object cat = null;
                switch (category) {
                case DISPLAY:
                    cat = eDISPLAY;
                    break;
                case FORMAT:
                    cat = eFORMAT;
                    break;
                }
                if (cat != null) {
                    try {
                        mSetDefault.invoke(null, cat, newLocale);
                    } catch (InvocationTargetException e) {
                        // fall through - no effects
                    } catch (IllegalArgumentException e) {
                        // fall through - no effects
                    } catch (IllegalAccessException e) {
                        // fall through - no effects
                    }
                }
            }
        }

        // Returns true if the given Locale matches the original
        // default locale initialized by JVM by checking user.XXX
        // system properties. When the system properties are not accessible,
        // this method returns false.
        public static boolean isOriginalDefaultLocale(Locale loc) {
            if (isJava7orNewer) {
                String script = "";
                try {
                    script = (String) mGetScript.invoke(loc, (Object[]) null);
                } catch (Exception e) {
                    return false;
                }

                return loc.getLanguage().equals(getSystemProperty("user.language"))
                        && loc.getCountry().equals(getSystemProperty("user.country"))
                        && loc.getVariant().equals(getSystemProperty("user.variant"))
                        && script.equals(getSystemProperty("user.script"));
            }
            return loc.getLanguage().equals(getSystemProperty("user.language"))
                    && loc.getCountry().equals(getSystemProperty("user.country"))
                    && loc.getVariant().equals(getSystemProperty("user.variant"));
        }

        public static String getSystemProperty(String key) {
            String val = null;
            final String fkey = key;
            if (System.getSecurityManager() != null) {
                try {
                    val = AccessController.doPrivileged(new PrivilegedAction<String>() {
                        public String run() {
                            return System.getProperty(fkey);
                        }
                    });
                } catch (AccessControlException e) {
                    // ignore
                }
            } else {
                val = System.getProperty(fkey);
            }
            return val;
        }
    }
}