/*
 *******************************************************************************
 * Copyright (C) 1996-2006, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 */

package com.ibm.icu.text;

import java.text.FieldPosition;
import java.text.Format;
import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Date;
import java.util.Locale;

import com.ibm.icu.util.Calendar;
import com.ibm.icu.util.TimeZone;
import com.ibm.icu.util.ULocale;

/**
 * DateFormat is an abstract class for date/time formatting subclasses which
 * formats and parses dates or time in a language-independent manner.
 * The date/time formatting subclass, such as SimpleDateFormat, allows for
 * formatting (i.e., date -> text), parsing (text -> date), and
 * normalization.  The date is represented as a <code>Date</code> object or
 * as the milliseconds since January 1, 1970, 00:00:00 GMT.
 *
 * <p>DateFormat provides many class methods for obtaining default date/time
 * formatters based on the default or a given loacle and a number of formatting
 * styles. The formatting styles include FULL, LONG, MEDIUM, and SHORT. More
 * detail and examples of using these styles are provided in the method
 * descriptions.
 *
 * <p>DateFormat helps you to format and parse dates for any locale.
 * Your code can be completely independent of the locale conventions for
 * months, days of the week, or even the calendar format: lunar vs. solar.
 *
 * <p>To format a date for the current Locale, use one of the
 * static factory methods:
 * <pre>
 *  myString = DateFormat.getDateInstance().format(myDate);
 * </pre>
 * <p>If you are formatting multiple numbers, it is
 * more efficient to get the format and use it multiple times so that
 * the system doesn't have to fetch the information about the local
 * language and country conventions multiple times.
 * <pre>
 *  DateFormat df = DateFormat.getDateInstance();
 *  for (int i = 0; i < a.length; ++i) {
 *    output.println(df.format(myDate[i]) + "; ");
 *  }
 * </pre>
 * <p>To format a number for a different Locale, specify it in the
 * call to getDateInstance().
 * <pre>
 *  DateFormat df = DateFormat.getDateInstance(DateFormat.LONG, Locale.FRANCE);
 * </pre>
 * <p>You can use a DateFormat to parse also.
 * <pre>
 *  myDate = df.parse(myString);
 * </pre>
 * <p>Use getDateInstance to get the normal date format for that country.
 * There are other static factory methods available.
 * Use getTimeInstance to get the time format for that country.
 * Use getDateTimeInstance to get a date and time format. You can pass in 
 * different options to these factory methods to control the length of the
 * result; from SHORT to MEDIUM to LONG to FULL. The exact result depends
 * on the locale, but generally:
 * <ul><li>SHORT is completely numeric, such as 12.13.52 or 3:30pm
 * <li>MEDIUM is longer, such as Jan 12, 1952
 * <li>LONG is longer, such as January 12, 1952 or 3:30:32pm
 * <li>FULL is pretty completely specified, such as
 * Tuesday, April 12, 1952 AD or 3:30:42pm PST.
 * </ul>
 *
 * <p>You can also set the time zone on the format if you wish.
 * If you want even more control over the format or parsing,
 * (or want to give your users more control),
 * you can try casting the DateFormat you get from the factory methods
 * to a SimpleDateFormat. This will work for the majority
 * of countries; just remember to put it in a try block in case you
 * encounter an unusual one.
 *
 * <p>You can also use forms of the parse and format methods with
 * ParsePosition and FieldPosition to
 * allow you to
 * <ul><li>progressively parse through pieces of a string.
 * <li>align any particular field, or find out where it is for selection
 * on the screen.
 * </ul>
 *
 * <h4>Synchronization</h4>
 *
 * Date formats are not synchronized. It is recommended to create separate 
 * format instances for each thread. If multiple threads access a format 
 * concurrently, it must be synchronized externally. 
 *
 * @see          UFormat
 * @see          NumberFormat
 * @see          SimpleDateFormat
 * @see          com.ibm.icu.util.Calendar
 * @see          com.ibm.icu.util.GregorianCalendar
 * @see          com.ibm.icu.util.TimeZone
 * @author       Mark Davis, Chen-Lieh Huang, Alan Liu
 * @stable ICU 2.0
 */
public class DateFormat extends Format {
    private static final long serialVersionUID = 1;

    /**
     * @internal
     */
    public final java.text.DateFormat dateFormat;
        
    /**
     * @internal
     * @param delegate the DateFormat to which to delegate
     */
    public DateFormat(java.text.DateFormat delegate) {
        this.dateFormat = delegate;
    }
    
    /**
     * For subclass use.  Subclasses will generally not
     * work correctly unless they manipulate the delegate.
     */
    protected DateFormat() {
    	this.dateFormat = java.text.DateFormat.getInstance();
    }

    /**
     * FieldPosition selector for 'G' field alignment,
     * corresponding to the {@link Calendar#ERA} field.
     * @stable ICU 2.0
     */
    public final static int ERA_FIELD = 0;

    /**
     * FieldPosition selector for 'y' field alignment,
     * corresponding to the {@link Calendar#YEAR} field.
     * @stable ICU 2.0
     */
    public final static int YEAR_FIELD = 1;

    /**
     * FieldPosition selector for 'M' field alignment,
     * corresponding to the {@link Calendar#MONTH} field.
     * @stable ICU 2.0
     */
    public final static int MONTH_FIELD = 2;

    /**
     * FieldPosition selector for 'd' field alignment,
     * corresponding to the {@link Calendar#DATE} field.
     * @stable ICU 2.0
     */
    public final static int DATE_FIELD = 3;

    /**
     * FieldPosition selector for 'k' field alignment,
     * corresponding to the {@link Calendar#HOUR_OF_DAY} field.
     * HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
     * For example, 23:59 + 01:00 results in 24:59.
     * @stable ICU 2.0
     */
    public final static int HOUR_OF_DAY1_FIELD = 4;

    /**
     * FieldPosition selector for 'H' field alignment,
     * corresponding to the {@link Calendar#HOUR_OF_DAY} field.
     * HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
     * For example, 23:59 + 01:00 results in 00:59.
     * @stable ICU 2.0
     */
    public final static int HOUR_OF_DAY0_FIELD = 5;

    /**
     * FieldPosition selector for 'm' field alignment,
     * corresponding to the {@link Calendar#MINUTE} field.
     * @stable ICU 2.0
     */
    public final static int MINUTE_FIELD = 6;

    /**
     * FieldPosition selector for 's' field alignment,
     * corresponding to the {@link Calendar#SECOND} field.
     * @stable ICU 2.0
     */
    public final static int SECOND_FIELD = 7;

    /**
     * FieldPosition selector for 'S' field alignment,
     * corresponding to the {@link Calendar#MILLISECOND} field.
     * @draft ICU 3.0
     * @provisional
     */
    public final static int FRACTIONAL_SECOND_FIELD = 8;

    /**
     * Alias for FRACTIONAL_SECOND_FIELD.
     * @stable ICU 3.4.3
     */
    public final static int MILLISECOND_FIELD = FRACTIONAL_SECOND_FIELD;

    /**
     * FieldPosition selector for 'E' field alignment,
     * corresponding to the {@link Calendar#DAY_OF_WEEK} field.
     * @stable ICU 2.0
     */
    public final static int DAY_OF_WEEK_FIELD = 9;

    /**
     * FieldPosition selector for 'D' field alignment,
     * corresponding to the {@link Calendar#DAY_OF_YEAR} field.
     * @stable ICU 2.0
     */
    public final static int DAY_OF_YEAR_FIELD = 10;

    /**
     * FieldPosition selector for 'F' field alignment,
     * corresponding to the {@link Calendar#DAY_OF_WEEK_IN_MONTH} field.
     * @stable ICU 2.0
     */
    public final static int DAY_OF_WEEK_IN_MONTH_FIELD = 11;

    /**
     * FieldPosition selector for 'w' field alignment,
     * corresponding to the {@link Calendar#WEEK_OF_YEAR} field.
     * @stable ICU 2.0
     */
    public final static int WEEK_OF_YEAR_FIELD = 12;

    /**
     * FieldPosition selector for 'W' field alignment,
     * corresponding to the {@link Calendar#WEEK_OF_MONTH} field.
     * @stable ICU 2.0
     */
    public final static int WEEK_OF_MONTH_FIELD = 13;

    /**
     * FieldPosition selector for 'a' field alignment,
     * corresponding to the {@link Calendar#AM_PM} field.
     * @stable ICU 2.0
     */
    public final static int AM_PM_FIELD = 14;

    /**
     * FieldPosition selector for 'h' field alignment,
     * corresponding to the {@link Calendar#HOUR} field.
     * HOUR1_FIELD is used for the one-based 12-hour clock.
     * For example, 11:30 PM + 1 hour results in 12:30 AM.
     * @stable ICU 2.0
     */
    public final static int HOUR1_FIELD = 15;

    /**
     * FieldPosition selector for 'K' field alignment,
     * corresponding to the {@link Calendar#HOUR} field.
     * HOUR0_FIELD is used for the zero-based 12-hour clock.
     * For example, 11:30 PM + 1 hour results in 00:30 AM.
     * @stable ICU 2.0
     */
    public final static int HOUR0_FIELD = 16;

    /**
     * FieldPosition selector for 'z' field alignment,
     * corresponding to the {@link Calendar#ZONE_OFFSET} and
     * {@link Calendar#DST_OFFSET} fields.
     * @stable ICU 2.0
     */
    public final static int TIMEZONE_FIELD = 17;

    /**
     * Overrides Format.
     * Formats a time object into a time string. Examples of time objects
     * are a time value expressed in milliseconds and a Date object.
     * @param obj must be a Number or a Date or a Calendar.
     * @param toAppendTo the string buffer for the returning time string.
     * @return the formatted time string.
     * @param fieldPosition keeps track of the position of the field
     * within the returned string.
     * On input: an alignment field,
     * if desired. On output: the offsets of the alignment field. For
     * example, given a time text "1996.07.10 AD at 15:08:56 PDT",
     * if the given fieldPosition is DateFormat.YEAR_FIELD, the
     * begin index and end index of fieldPosition will be set to
     * 0 and 4, respectively.
     * Notice that if the same time field appears
     * more than once in a pattern, the fieldPosition will be set for the first
     * occurence of that time field. For instance, formatting a Date to
     * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
     * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
     * the begin index and end index of fieldPosition will be set to
     * 5 and 8, respectively, for the first occurence of the timezone
     * pattern character 'z'.
     * @see java.text.Format
     * @stable ICU 2.0
     */
    public final StringBuffer format(Object obj, StringBuffer toAppendTo, FieldPosition fieldPosition) {
        if (obj instanceof Calendar) {
            return format((Calendar)obj, toAppendTo, fieldPosition);
        } else if (obj instanceof Date) {
            return format((Date)obj, toAppendTo, fieldPosition);
        } else if (obj instanceof Number) {
            return format(new Date(((Number)obj).longValue()), toAppendTo, fieldPosition );
        } else {
            throw new IllegalArgumentException("Cannot format given Object as a Date");
        }
    }

    /**
     * Formats a date into a date/time string.
     * @param cal a Calendar set to the date and time to be formatted
     * into a date/time string.
     * @param toAppendTo the string buffer for the returning date/time string.
     * @param fieldPosition keeps track of the position of the field
     * within the returned string.
     * On input: an alignment field,
     * if desired. On output: the offsets of the alignment field. For
     * example, given a time text "1996.07.10 AD at 15:08:56 PDT",
     * if the given fieldPosition is DateFormat.YEAR_FIELD, the
     * begin index and end index of fieldPosition will be set to
     * 0 and 4, respectively.
     * Notice that if the same time field appears
     * more than once in a pattern, the fieldPosition will be set for the first
     * occurence of that time field. For instance, formatting a Date to
     * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
     * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
     * the begin index and end index of fieldPosition will be set to
     * 5 and 8, respectively, for the first occurence of the timezone
     * pattern character 'z'.
     * @return the formatted date/time string.
     * @stable ICU 2.0
     */
    public StringBuffer format(Calendar cal, StringBuffer toAppendTo, FieldPosition fieldPosition) {
        return format(cal.getTime(), toAppendTo, fieldPosition);
    }
    

    /**
     * Formats a Date into a date/time string.
     * @param date a Date to be formatted into a date/time string.
     * @param toAppendTo the string buffer for the returning date/time string.
     * @param fieldPosition keeps track of the position of the field
     * within the returned string.
     * On input: an alignment field,
     * if desired. On output: the offsets of the alignment field. For
     * example, given a time text "1996.07.10 AD at 15:08:56 PDT",
     * if the given fieldPosition is DateFormat.YEAR_FIELD, the
     * begin index and end index of fieldPosition will be set to
     * 0 and 4, respectively.
     * Notice that if the same time field appears
     * more than once in a pattern, the fieldPosition will be set for the first
     * occurence of that time field. For instance, formatting a Date to
     * the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
     * "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
     * the begin index and end index of fieldPosition will be set to
     * 5 and 8, respectively, for the first occurence of the timezone
     * pattern character 'z'.
     * @return the formatted date/time string.
     * @stable ICU 2.0
     */
    public StringBuffer format(Date date, StringBuffer toAppendTo, FieldPosition fieldPosition) {
        return dateFormat.format(date, toAppendTo, fieldPosition);
    }

    /**
     * Formats a Date into a date/time string.
     * @param date the time value to be formatted into a time string.
     * @return the formatted time string.
     * @stable ICU 2.0
     */
    public final String format(Date date) {
        return dateFormat.format(date);
    }

    /**
     * Parse a date/time string.
     *
     * @param text  The date/time string to be parsed
     *
     * @return      A Date, or null if the input could not be parsed
     *
     * @exception  ParseException  If the given string cannot be parsed as a date.
     *
     * @see #parse(String, ParsePosition)
     * @stable ICU 2.0
     */
    public Date parse(String text) throws ParseException {
        return dateFormat.parse(text);
    }

    /**
     * Parse a date/time string according to the given parse position.
     * For example, a time text "07/10/96 4:5 PM, PDT" will be parsed
     * into a Calendar that is equivalent to Date(837039928046).  The
     * caller should clear the calendar before calling this method,
     * unless existing field information is to be kept.
     *
     * <p> By default, parsing is lenient: If the input is not in the form used
     * by this object's format method but can still be parsed as a date, then
     * the parse succeeds.  Clients may insist on strict adherence to the
     * format by calling setLenient(false).
     *
     * @see #setLenient(boolean)
     *
     * @param text  The date/time string to be parsed
     *
     * @param cal   The calendar into which parsed data will be stored.
     *              In general, this should be cleared before calling this
     *              method.  If this parse fails, the calendar may still
     *              have been modified.
     *
     * @param pos   On input, the position at which to start parsing; on
     *              output, the position at which parsing terminated, or the
     *              start position if the parse failed.
     * @stable ICU 2.0
     */
    public void parse(String text, Calendar cal, ParsePosition pos) {
        Date result = dateFormat.parse(text, pos);
        cal.setTime(result);
    }

    /**
     * Parse a date/time string according to the given parse position.  For
     * example, a time text "07/10/96 4:5 PM, PDT" will be parsed into a Date
     * that is equivalent to Date(837039928046).
     *
     * <p> By default, parsing is lenient: If the input is not in the form used
     * by this object's format method but can still be parsed as a date, then
     * the parse succeeds.  Clients may insist on strict adherence to the
     * format by calling setLenient(false).
     *
     * @see #setLenient(boolean)
     *
     * @param text  The date/time string to be parsed
     *
     * @param pos   On input, the position at which to start parsing; on
     *              output, the position at which parsing terminated, or the
     *              start position if the parse failed.
     *
     * @return      A Date, or null if the input could not be parsed
     * @stable ICU 2.0
     */
    public Date parse(String text, ParsePosition pos) {
        return dateFormat.parse(text, pos);
    }

    /**
     * Parse a date/time string into an Object.  This convenience method simply
     * calls parse(String, ParsePosition).
     *
     * @see #parse(String, ParsePosition)
     * @stable ICU 2.0
     */
    public Object parseObject(String source, ParsePosition pos) {
        return parse(source, pos);
    }

    /**
     * Constant for full style pattern.
     * @stable ICU 2.0
     */
    public static final int FULL = 0;

    /**
     * Constant for long style pattern.
     * @stable ICU 2.0
     */
    public static final int LONG = 1;

    /**
     * Constant for medium style pattern.
     * @stable ICU 2.0
     */
    public static final int MEDIUM = 2;

    /**
     * Constant for short style pattern.
     * @stable ICU 2.0
     */
    public static final int SHORT = 3;

    /**
     * Constant for default style pattern.  Its value is MEDIUM.
     * @stable ICU 2.0
     */
    public static final int DEFAULT = MEDIUM;

    /**
     * Gets the time formatter with the default formatting style
     * for the default locale.
     * @return a time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getTimeInstance() {
        return new DateFormat(java.text.DateFormat.getTimeInstance());
    }

    /**
     * Gets the time formatter with the given formatting style
     * for the default locale.
     * @param style the given formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @return a time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getTimeInstance(int style) {
        return new DateFormat(java.text.DateFormat.getTimeInstance(style));
    }

    /**
     * Gets the time formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @param aLocale the given locale.
     * @return a time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getTimeInstance(int style, Locale aLocale) {
        return new DateFormat(java.text.DateFormat.getTimeInstance(style, aLocale));
    }

    /**
     * Gets the time formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @param aLocale the given locale.
     * @return a time formatter.
     * @draft ICU 3.2
     */
    public final static DateFormat getTimeInstance(int style, ULocale aLocale) {
        return new DateFormat(java.text.DateFormat.getTimeInstance(style, aLocale.toLocale()));
    }

    /**
     * Gets the date formatter with the default formatting style
     * for the default locale.
     * @return a date formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateInstance() {
        return new DateFormat(java.text.DateFormat.getDateInstance());
    }

    /**
     * Gets the date formatter with the given formatting style
     * for the default locale.
     * @param style the given formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @return a date formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateInstance(int style) {
        return new DateFormat(java.text.DateFormat.getDateInstance(style));
    }

    /**
     * Gets the date formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @param aLocale the given locale.
     * @return a date formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateInstance(int style, Locale aLocale) {
        return new DateFormat(java.text.DateFormat.getDateInstance(style, aLocale));
    }

    /**
     * Gets the date formatter with the given formatting style
     * for the given locale.
     * @param style the given formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @param aLocale the given locale.
     * @return a date formatter.
     * @stable ICU 3.4.3
     */
    public final static DateFormat getDateInstance(int style, ULocale aLocale) {
        return new DateFormat(java.text.DateFormat.getDateInstance(style, aLocale.toLocale()));
    }

    /**
     * Gets the date/time formatter with the default formatting style
     * for the default locale.
     * @return a date/time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateTimeInstance() {
        return new DateFormat(java.text.DateFormat.getDateTimeInstance());
    }

    /**
     * Gets the date/time formatter with the given date and time
     * formatting styles for the default locale.
     * @param dateStyle the given date formatting style. For example,
     * SHORT for "M/d/yy" in the US locale.
     * @param timeStyle the given time formatting style. For example,
     * SHORT for "h:mm a" in the US locale.
     * @return a date/time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateTimeInstance(int dateStyle, int timeStyle) {
        return new DateFormat(java.text.DateFormat.getDateTimeInstance(dateStyle, timeStyle));
    }

    /**
     * Gets the date/time formatter with the given formatting styles
     * for the given locale.
     * @param dateStyle the given date formatting style.
     * @param timeStyle the given time formatting style.
     * @param aLocale the given locale.
     * @return a date/time formatter.
     * @stable ICU 2.0
     */
    public final static DateFormat getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale) {
        return new DateFormat(java.text.DateFormat.getDateTimeInstance(dateStyle, timeStyle, aLocale));
    }

    /**
     * Gets the date/time formatter with the given formatting styles
     * for the given locale.
     * @param dateStyle the given date formatting style.
     * @param timeStyle the given time formatting style.
     * @param aLocale the given locale.
     * @return a date/time formatter.
     * @stable ICU 3.4.3
     */
    public final static DateFormat getDateTimeInstance(int dateStyle, int timeStyle, ULocale aLocale) {
        return new DateFormat(java.text.DateFormat.getDateTimeInstance(dateStyle, timeStyle, aLocale.toLocale()));
    }

    /**
     * Get a default date/time formatter that uses the SHORT style for both the
     * date and the time.
     * @stable ICU 2.0
     */
    public final static DateFormat getInstance() {
        return new DateFormat(java.text.DateFormat.getInstance());
    }

    /**
     * Gets the set of locales for which DateFormats are installed.
     * @return the set of locales for which DateFormats are installed.
     * @stable ICU 2.0
     */
    public static Locale[] getAvailableLocales() {
        return java.text.DateFormat.getAvailableLocales();
    }

    /**
     * Gets the set of locales for which DateFormats are installed.
     * @return the set of locales for which DateFormats are installed.
     * @stable ICU 3.4.3
     */
    public static ULocale[] getAvailableULocales() {
        Locale[] locales = java.text.DateFormat.getAvailableLocales();
        ULocale[] ulocales = new ULocale[locales.length];
        for (int i = 0; i < locales.length; ++i) {
            ulocales[i] = ULocale.forLocale(locales[i]);
        }
        return ulocales;
    }

    /**
     * Set the calendar to be used by this date format.  Initially, the default
     * calendar for the specified or default locale is used.
     * @param newCalendar the new Calendar to be used by the date format
     * @stable ICU 2.0
     */
    public void setCalendar(Calendar newCalendar) {
        dateFormat.setCalendar(newCalendar.calendar);
    }

    /**
     * Gets the calendar associated with this date/time formatter.
     * @return the calendar associated with this date/time formatter.
     * @stable ICU 2.0
     */
    public Calendar getCalendar() {
        return new Calendar(dateFormat.getCalendar());
    }

    /**
     * Allows you to set the number formatter.
     * @param newNumberFormat the given new NumberFormat.
     * @stable ICU 2.0
     */
    public void setNumberFormat(NumberFormat newNumberFormat) {
        dateFormat.setNumberFormat(newNumberFormat.numberFormat);
    }

    /**
     * Gets the number formatter which this date/time formatter uses to
     * format and parse a time.
     * @return the number formatter which this date/time formatter uses.
     * @stable ICU 2.0
     */
    public NumberFormat getNumberFormat() {
        return new NumberFormat(dateFormat.getNumberFormat());
    }

    /**
     * Sets the time zone for the calendar of this DateFormat object.
     * @param zone the given new time zone.
     * @stable ICU 2.0
     */
    public void setTimeZone(TimeZone zone) {
        dateFormat.setTimeZone(zone.timeZone);
    }

    /**
     * Gets the time zone.
     * @return the time zone associated with the calendar of DateFormat.
     * @stable ICU 2.0
     */
    public TimeZone getTimeZone() {
        return new TimeZone(dateFormat.getTimeZone());
    }

    /**
     * Specify whether or not date/time parsing is to be lenient.  With
     * lenient parsing, the parser may use heuristics to interpret inputs that
     * do not precisely match this object's format.  With strict parsing,
     * inputs must match this object's format.
     * @param lenient when true, parsing is lenient
     * @see com.ibm.icu.util.Calendar#setLenient
     * @stable ICU 2.0
     */
    public void setLenient(boolean lenient) {
        dateFormat.setLenient(lenient);
    }

    /**
     * Tell whether date/time parsing is to be lenient.
     * @stable ICU 2.0
     */
    public boolean isLenient() {
        return dateFormat.isLenient();
    }
   
    /**
     * Create a {@link DateFormat} object that can be used to format dates in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * @param cal   The calendar system for which a date format is desired.
     *
     * @param dateStyle The type of date format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the date format is desired.
     * @stable ICU 2.0
     */
    static final public DateFormat getDateInstance(Calendar cal, int dateStyle, Locale locale) {
        DateFormat df = getDateInstance(dateStyle, locale);
        df.setCalendar(cal);
        return df;
    }
    
    /**
     * Create a {@link DateFormat} object that can be used to format dates in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * @param cal   The calendar system for which a date format is desired.
     *
     * @param dateStyle The type of date format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the date format is desired.
     * @draft ICU 3.2
     * @provisional
     */
    static final public DateFormat getDateInstance(Calendar cal, int dateStyle, ULocale locale) {
        DateFormat df = getDateInstance(dateStyle, locale);
        df.setCalendar(cal);
        return df;
    }
      
    /**
     * Create a {@link DateFormat} object that can be used to format times in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * <b>Note:</b> When this functionality is moved into the core JDK, this method
     * will probably be replaced by a new overload of {@link DateFormat#getInstance}.
     * <p>
     * @param cal   The calendar system for which a time format is desired.
     *
     * @param timeStyle The type of time format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the time format is desired.
     *
     * @see DateFormat#getTimeInstance
     * @stable ICU 2.0
     */
    static final public DateFormat getTimeInstance(Calendar cal, int timeStyle, Locale locale) {
        DateFormat df = getTimeInstance(timeStyle, locale);
        df.setCalendar(cal);
        return df;
    }
    
    /**
     * Create a {@link DateFormat} object that can be used to format times in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * <b>Note:</b> When this functionality is moved into the core JDK, this method
     * will probably be replaced by a new overload of {@link DateFormat#getInstance}.
     * <p>
     * @param cal   The calendar system for which a time format is desired.
     *
     * @param timeStyle The type of time format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the time format is desired.
     *
     * @see DateFormat#getTimeInstance
     * @draft ICU 3.2
     * @provisional
     */
    static final public DateFormat getTimeInstance(Calendar cal, int timeStyle, ULocale locale) {
        DateFormat df = getTimeInstance(timeStyle, locale);
        df.setCalendar(cal);
        return df;
    }
       
    /**
     * Create a {@link DateFormat} object that can be used to format dates and times in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * <b>Note:</b> When this functionality is moved into the core JDK, this method
     * will probably be replaced by a new overload of {@link DateFormat#getInstance}.
     * <p>
     * @param cal   The calendar system for which a date/time format is desired.
     *
     * @param dateStyle The type of date format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param timeStyle The type of time format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the date/time format is desired.
     *
     * @see DateFormat#getDateTimeInstance
     * @stable ICU 2.0
     */
    static final public DateFormat getDateTimeInstance(Calendar cal, int dateStyle,
                                                       int timeStyle, Locale locale) {
        DateFormat df = getDateTimeInstance(dateStyle, timeStyle, locale);
        df.setCalendar(cal);
        return df;
    }

    /**
     * Create a {@link DateFormat} object that can be used to format dates and times in
     * the calendar system specified by <code>cal</code>.
     * <p>
     * <b>Note:</b> When this functionality is moved into the core JDK, this method
     * will probably be replaced by a new overload of {@link DateFormat#getInstance}.
     * <p>
     * @param cal   The calendar system for which a date/time format is desired.
     *
     * @param dateStyle The type of date format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param timeStyle The type of time format desired.  This can be
     *              {@link DateFormat#SHORT}, {@link DateFormat#MEDIUM},
     *              etc.
     *
     * @param locale The locale for which the date/time format is desired.
     *
     * @see DateFormat#getDateTimeInstance
     * @draft ICU 3.2
     * @provisional
     */
    static final public DateFormat getDateTimeInstance(Calendar cal, int dateStyle,
                                                       int timeStyle, ULocale locale) {
        DateFormat df = getDateTimeInstance(dateStyle, timeStyle, locale);
        df.setCalendar(cal);
        return df;
    }

    /**
     * Convenience overload
     * @stable ICU 2.0
     */
    static final public DateFormat getInstance(Calendar cal, Locale locale) {
        return getDateTimeInstance(cal, MEDIUM, SHORT, locale);
    }

    /**
     * Convenience overload
     * @draft ICU 3.2
     * @provisional
     */
    public static final DateFormat getInstance(Calendar cal, ULocale locale) {
        return getDateTimeInstance(cal, MEDIUM, SHORT, locale);
    }

    /**
     * Convenience overload
     * @stable ICU 2.0
     */
    public static final DateFormat getInstance(Calendar cal) {
        return getDateTimeInstance(cal, MEDIUM, SHORT, ULocale.getDefault());
    }

    /**
     * Convenience overload
     * @stable ICU 2.0
     */
    public static final DateFormat getDateInstance(Calendar cal, int dateStyle) {
        DateFormat df = getDateInstance(dateStyle);
        df.setCalendar(cal);
        return df;
    }

    /**
     * Convenience overload
     * @stable ICU 2.0
     */
    static final public DateFormat getTimeInstance(Calendar cal, int timeStyle) {
        DateFormat df = getTimeInstance(timeStyle);
        df.setCalendar(cal);
        return df;
    }

    /**
     * Convenience overload
     * @stable ICU 2.0
     */
    static final public DateFormat getDateTimeInstance(Calendar cal, int dateStyle, int timeStyle) {
        DateFormat df = getDateTimeInstance(dateStyle, timeStyle);
        df.setCalendar(cal);
        return df;
    }

    /**
     * Return a string suitable for debugging.
     * @return a string suitable for debugging
     * @stable ICU 3.4.3
     */
    public String toString() {
        return dateFormat.toString();
    }
        
    /**
     * Return a clone of this DateFormat.
     * @return a clone of this DateFormat
     * @stable ICU 3.4.3
     */
    public Object clone() {
        return new DateFormat((java.text.DateFormat)dateFormat.clone());
    }

    /**
     * Return true if rhs is a DateFormatSymbols and has the same symbols as this.
     * @return true if rhs equals this
     * @stable ICU 3.4.3
     */
    public boolean equals(Object arg0) {
        try {
            return dateFormat.equals(((DateFormat)arg0).dateFormat);
        }
        catch (Exception e) {
            return false;
        }
    }
        
    /**
     * Return a hashCode.
     * @return a hashCode
     * @stable ICU 3.4.3
     */
    public int hashCode() {
        return dateFormat.hashCode();
    }
}