/*
 *******************************************************************************
 * Copyright (C) 1996-2006, International Business Machines Corporation and    *
 * others. All Rights Reserved.                                                *
 *******************************************************************************
 */

package com.ibm.icu.text;

/**
 * <code>DecimalFormat</code> is a concrete subclass of
 * {@link NumberFormat} that formats decimal numbers.
 *
 * <p>To obtain a {@link NumberFormat} for a specific locale (including the
 * default locale) call one of <code>NumberFormat</code>'s factory methods such
 * as {@link NumberFormat#getInstance}. Do not call the <code>DecimalFormat</code>
 * constructors directly, unless you know what you are doing, since the
 * {@link NumberFormat} factory methods may return subclasses other than
 * <code>DecimalFormat</code>. If you need to customize the format object, do
 * something like this:
 *
 * <blockquote><pre>
 * NumberFormat f = NumberFormat.getInstance(loc);
 * if (f instanceof DecimalFormat) {
 *     ((DecimalFormat) f).setDecimalSeparatorAlwaysShown(true);
 * }</pre></blockquote>
 *
 * <p><strong>Example Usage</strong>
 *
 * <blockquote><pre>
 * <strong>// Print out a number using the localized number, currency,
 * // and percent format for each locale</strong>
 * Locale[] locales = NumberFormat.getAvailableLocales();
 * double myNumber = -1234.56;
 * NumberFormat format;
 * for (int j=0; j<3; ++j) {
 *     System.out.println("FORMAT");
 *     for (int i = 0; i < locales.length; ++i) {
 *         if (locales[i].getCountry().length() == 0) {
 *            // Skip language-only locales
 *            continue;
 *         }
 *         System.out.print(locales[i].getDisplayName());
 *         switch (j) {
 *         case 0:
 *             format = NumberFormat.getInstance(locales[i]); break;
 *         case 1:
 *             format = NumberFormat.getCurrencyInstance(locales[i]); break;
 *         default:
 *             format = NumberFormat.getPercentInstance(locales[i]); break;
 *         }
 *         try {
 *             // Assume format is a DecimalFormat
 *             System.out.print(": " + ((DecimalFormat) format).toPattern()
 *                              + " -> " + form.format(myNumber));
 *         } catch (Exception e) {}
 *         try {
 *             System.out.println(" -> " + format.parse(form.format(myNumber)));
 *         } catch (ParseException e) {}
 *     }
 * }</pre></blockquote>
 *
 * <h4>Patterns</h4>
 *
 * <p>A <code>DecimalFormat</code> consists of a <em>pattern</em> and a set of
 * <em>symbols</em>.  The pattern may be set directly using
 * {@link #applyPattern}, or indirectly using other API methods which
 * manipulate aspects of the pattern, such as the minimum number of integer
 * digits.  The symbols are stored in a {@link DecimalFormatSymbols}
 * object.  When using the {@link NumberFormat} factory methods, the
 * pattern and symbols are read from ICU's locale data.
 * 
 * <h4>Special Pattern Characters</h4>
 *
 * <p>Many characters in a pattern are taken literally; they are matched during
 * parsing and output unchanged during formatting.  Special characters, on the
 * other hand, stand for other characters, strings, or classes of characters.
 * For example, the '#' character is replaced by a localized digit.  Often the
 * replacement character is the same as the pattern character; in the U.S. locale,
 * the ',' grouping character is replaced by ','.  However, the replacement is
 * still happening, and if the symbols are modified, the grouping character
 * changes.  Some special characters affect the behavior of the formatter by
 * their presence; for example, if the percent character is seen, then the
 * value is multiplied by 100 before being displayed.
 *
 * <p>To insert a special character in a pattern as a literal, that is, without
 * any special meaning, the character must be quoted.  There are some exceptions to
 * this which are noted below.
 *
 * <p>The characters listed here are used in non-localized patterns.  Localized
 * patterns use the corresponding characters taken from this formatter's
 * {@link DecimalFormatSymbols} object instead, and these characters lose
 * their special status.  Two exceptions are the currency sign and quote, which
 * are not localized.
 *
 * <blockquote>
 * <table border=0 cellspacing=3 cellpadding=0 summary="Chart showing symbol,
 *  location, localized, and meaning.">
 *   <tr bgcolor="#ccccff">
 *     <th align=left>Symbol
 *     <th align=left>Location
 *     <th align=left>Localized?
 *     <th align=left>Meaning
 *   <tr valign=top>
 *     <td><code>0</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Digit
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>1-9</code>
 *     <td>Number
 *     <td>Yes
 *     <td><strong><font face=helvetica color=red>NEW</font></strong>
 *         '1' through '9' indicate rounding.
 *   <tr valign=top>
 *     <td><code>@</code>
 *     <td>Number
 *     <td>No
 *     <td><strong><font face=helvetica color=red>NEW</font></strong>
 *         Significant digit
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>#</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Digit, zero shows as absent
 *   <tr valign=top>
 *     <td><code>.</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Decimal separator or monetary decimal separator
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>-</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Minus sign
 *   <tr valign=top>
 *     <td><code>,</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Grouping separator
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>E</code>
 *     <td>Number
 *     <td>Yes
 *     <td>Separates mantissa and exponent in scientific notation.
 *         <em>Need not be quoted in prefix or suffix.</em>
 *   <tr valign=top>
 *     <td><code>+</code>
 *     <td>Exponent
 *     <td>Yes
 *     <td><strong><font face=helvetica color=red>NEW</font></strong>
 *         Prefix positive exponents with localized plus sign.
 *         <em>Need not be quoted in prefix or suffix.</em>
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>;</code>
 *     <td>Subpattern boundary
 *     <td>Yes
 *     <td>Separates positive and negative subpatterns
 *   <tr valign=top>
 *     <td><code>%</code>
 *     <td>Prefix or suffix
 *     <td>Yes
 *     <td>Multiply by 100 and show as percentage
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>&#92;u2030</code>
 *     <td>Prefix or suffix
 *     <td>Yes
 *     <td>Multiply by 1000 and show as per mille
 *   <tr valign=top>
 *     <td><code>&#164;</code> (<code>&#92;u00A4</code>)
 *     <td>Prefix or suffix
 *     <td>No
 *     <td>Currency sign, replaced by currency symbol.  If
 *         doubled, replaced by international currency symbol.
 *         If present in a pattern, the monetary decimal separator
 *         is used instead of the decimal separator.
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>'</code>
 *     <td>Prefix or suffix
 *     <td>No
 *     <td>Used to quote special characters in a prefix or suffix,
 *         for example, <code>"'#'#"</code> formats 123 to
 *         <code>"#123"</code>.  To create a single quote
 *         itself, use two in a row: <code>"# o''clock"</code>.
 *   <tr valign=top>
 *     <td><code>*</code>
 *     <td>Prefix or suffix boundary
 *     <td>Yes
 *     <td><strong><font face=helvetica color=red>NEW</font></strong>
 *         Pad escape, precedes pad character
 * </table>
 * </blockquote>
 *
 * <p>A <code>DecimalFormat</code> pattern contains a postive and negative
 * subpattern, for example, "#,##0.00;(#,##0.00)".  Each subpattern has a
 * prefix, a numeric part, and a suffix.  If there is no explicit negative
 * subpattern, the negative subpattern is the localized minus sign prefixed to the
 * positive subpattern. That is, "0.00" alone is equivalent to "0.00;-0.00".  If there
 * is an explicit negative subpattern, it serves only to specify the negative
 * prefix and suffix; the number of digits, minimal digits, and other
 * characteristics are ignored in the negative subpattern. That means that
 * "#,##0.0#;(#)" has precisely the same result as "#,##0.0#;(#,##0.0#)".
 *
 * <p>The prefixes, suffixes, and various symbols used for infinity, digits,
 * thousands separators, decimal separators, etc. may be set to arbitrary
 * values, and they will appear properly during formatting.  However, care must
 * be taken that the symbols and strings do not conflict, or parsing will be
 * unreliable.  For example, either the positive and negative prefixes or the
 * suffixes must be distinct for {@link #parse} to be able
 * to distinguish positive from negative values.  Another example is that the
 * decimal separator and thousands separator should be distinct characters, or
 * parsing will be impossible.
 *
 * <p>The <em>grouping separator</em> is a character that separates clusters of
 * integer digits to make large numbers more legible.  It commonly used for
 * thousands, but in some locales it separates ten-thousands.  The <em>grouping
 * size</em> is the number of digits between the grouping separators, such as 3
 * for "100,000,000" or 4 for "1 0000 0000". There are actually two different
 * grouping sizes: One used for the least significant integer digits, the
 * <em>primary grouping size</em>, and one used for all others, the
 * <em>secondary grouping size</em>.  In most locales these are the same, but
 * sometimes they are different. For example, if the primary grouping interval
 * is 3, and the secondary is 2, then this corresponds to the pattern
 * "#,##,##0", and the number 123456789 is formatted as "12,34,56,789".  If a
 * pattern contains multiple grouping separators, the interval between the last
 * one and the end of the integer defines the primary grouping size, and the
 * interval between the last two defines the secondary grouping size. All others
 * are ignored, so "#,##,###,####" == "###,###,####" == "##,#,###,####".
 *
 * <p>Illegal patterns, such as "#.#.#" or "#.###,###", will cause
 * <code>DecimalFormat</code> to throw an {@link IllegalArgumentException}
 * with a message that describes the problem.
 *
 * <h4>Pattern BNF</h4>
 *
 * <pre>
 * pattern    := subpattern (';' subpattern)?
 * subpattern := prefix? number exponent? suffix?
 * number     := (integer ('.' fraction)?) | sigDigits
 * prefix     := '&#92;u0000'..'&#92;uFFFD' - specialCharacters
 * suffix     := '&#92;u0000'..'&#92;uFFFD' - specialCharacters
 * integer    := '#'* '0'* '0'
 * fraction   := '0'* '#'*
 * sigDigits  := '#'* '@' '@'* '#'*
 * exponent   := 'E' '+'? '0'* '0'
 * padSpec    := '*' padChar
 * padChar    := '&#92;u0000'..'&#92;uFFFD' - quote
 * &#32;
 * Notation:
 *   X*       0 or more instances of X
 *   X?       0 or 1 instances of X
 *   X|Y      either X or Y
 *   C..D     any character from C up to D, inclusive
 *   S-T      characters in S, except those in T
 * </pre>
 * The first subpattern is for positive numbers. The second (optional)
 * subpattern is for negative numbers.
 * 
 * <p>Not indicated in the BNF syntax above:
 *
 * <ul><li>The grouping separator ',' can occur inside the integer and
 * sigDigits elements, between any two pattern characters of that
 * element, as long as the integer or sigDigits element is not
 * followed by the exponent element.
 *
 * <li><font color=red face=helvetica><strong>NEW</strong></font>
 *     Two grouping intervals are recognized: That between the
 *     decimal point and the first grouping symbol, and that
 *     between the first and second grouping symbols. These
 *     intervals are identical in most locales, but in some
 *     locales they differ. For example, the pattern
 *     &quot;#,##,###&quot; formats the number 123456789 as
 *     &quot;12,34,56,789&quot;.</li>
 * 
 * <li>
 * <strong><font face=helvetica color=red>NEW</font></strong>
 * The pad specifier <code>padSpec</code> may appear before the prefix,
 * after the prefix, before the suffix, after the suffix, or not at all.
 *
 * <li>
 * <strong><font face=helvetica color=red>NEW</font></strong>
 * In place of '0', the digits '1' through '9' may be used to
 * indicate a rounding increment.
 * </ul>
 *
 * <h4>Parsing</h4>
 *
 * <p><code>DecimalFormat</code> parses all Unicode characters that represent
 * decimal digits, as defined by {@link UCharacter#digit}.  In addition,
 * <code>DecimalFormat</code> also recognizes as digits the ten consecutive
 * characters starting with the localized zero digit defined in the
 * {@link DecimalFormatSymbols} object.  During formatting, the
 * {@link DecimalFormatSymbols}-based digits are output.
 *
 * <p>During parsing, grouping separators are ignored.
 *
 * <p>If {@link #parse(String, ParsePosition)} fails to parse
 * a string, it returns <code>null</code> and leaves the parse position
 * unchanged.  The convenience method {@link #parse(String)}
 * indicates parse failure by throwing a {@link java.text.ParseException}.
 *
 * <h4>Formatting</h4>
 *
 * <p>Formatting is guided by several parameters, all of which can be
 * specified either using a pattern or using the API.  The following
 * description applies to formats that do not use <a href="#sci">scientific
 * notation</a> or <a href="#sigdig">significant digits</a>.
 *
 * <ul><li>If the number of actual integer digits exceeds the
 * <em>maximum integer digits</em>, then only the least significant
 * digits are shown.  For example, 1997 is formatted as "97" if the
 * maximum integer digits is set to 2.
 *
 * <li>If the number of actual integer digits is less than the
 * <em>minimum integer digits</em>, then leading zeros are added.  For
 * example, 1997 is formatted as "01997" if the minimum integer digits
 * is set to 5.
 *
 * <li>If the number of actual fraction digits exceeds the <em>maximum
 * fraction digits</em>, then half-even rounding it performed to the
 * maximum fraction digits.  For example, 0.125 is formatted as "0.12"
 * if the maximum fraction digits is 2.  This behavior can be changed
 * by specifying a rounding increment and a rounding mode.
 *
 * <li>If the number of actual fraction digits is less than the
 * <em>minimum fraction digits</em>, then trailing zeros are added.
 * For example, 0.125 is formatted as "0.1250" if the mimimum fraction
 * digits is set to 4.
 *
 * <li>Trailing fractional zeros are not displayed if they occur
 * <em>j</em> positions after the decimal, where <em>j</em> is less
 * than the maximum fraction digits. For example, 0.10004 is
 * formatted as "0.1" if the maximum fraction digits is four or less.
 * </ul>
 * 
 * <p><strong>Special Values</strong>
 *
 * <p><code>NaN</code> is represented as a single character, typically
 * <code>&#92;uFFFD</code>.  This character is determined by the
 * {@link DecimalFormatSymbols} object.  This is the only value for which
 * the prefixes and suffixes are not used.
 *
 * <p>Infinity is represented as a single character, typically
 * <code>&#92;u221E</code>, with the positive or negative prefixes and suffixes
 * applied.  The infinity character is determined by the
 * {@link DecimalFormatSymbols} object.
 *
 * <a name="sci"><h4>Scientific Notation</h4></a>
 *
 * <p>Numbers in scientific notation are expressed as the product of a mantissa
 * and a power of ten, for example, 1234 can be expressed as 1.234 x 10<sup>3</sup>. The
 * mantissa is typically in the half-open interval [1.0, 10.0) or sometimes [0.0, 1.0),
 * but it need not be.  <code>DecimalFormat</code> supports arbitrary mantissas.
 * <code>DecimalFormat</code> can be instructed to use scientific
 * notation through the API or through the pattern.  In a pattern, the exponent
 * character immediately followed by one or more digit characters indicates
 * scientific notation.  Example: "0.###E0" formats the number 1234 as
 * "1.234E3".
 *
 * <ul>
 * <li>The number of digit characters after the exponent character gives the
 * minimum exponent digit count.  There is no maximum.  Negative exponents are
 * formatted using the localized minus sign, <em>not</em> the prefix and suffix
 * from the pattern.  This allows patterns such as "0.###E0 m/s".  To prefix
 * positive exponents with a localized plus sign, specify '+' between the
 * exponent and the digits: "0.###E+0" will produce formats "1E+1", "1E+0",
 * "1E-1", etc.  (In localized patterns, use the localized plus sign rather than
 * '+'.)
 *
 * <li>The minimum number of integer digits is achieved by adjusting the
 * exponent.  Example: 0.00123 formatted with "00.###E0" yields "12.3E-4".  This
 * only happens if there is no maximum number of integer digits.  If there is a
 * maximum, then the minimum number of integer digits is fixed at one.
 *
 * <li>The maximum number of integer digits, if present, specifies the exponent
 * grouping.  The most common use of this is to generate <em>engineering
 * notation</em>, in which the exponent is a multiple of three, e.g.,
 * "##0.###E0".  The number 12345 is formatted using "##0.####E0" as "12.345E3".
 *
 * <li>When using scientific notation, the formatter controls the
 * digit counts using significant digits logic.  The maximum number of
 * significant digits limits the total number of integer and fraction
 * digits that will be shown in the mantissa; it does not affect
 * parsing.  For example, 12345 formatted with "##0.##E0" is "12.3E3".
 * See the section on significant digits for more details.
 *
 * <li>The number of significant digits shown is determined as
 * follows: If areSignificantDigitsUsed() returns false, then the
 * minimum number of significant digits shown is one, and the maximum
 * number of significant digits shown is the sum of the <em>minimum
 * integer</em> and <em>maximum fraction</em> digits, and is
 * unaffected by the maximum integer digits.  If this sum is zero,
 * then all significant digits are shown.  If
 * areSignificantDigitsUsed() returns true, then the significant digit
 * counts are specified by getMinimumSignificantDigits() and
 * getMaximumSignificantDigits().  In this case, the number of
 * integer digits is fixed at one, and there is no exponent grouping.
 *
 * <li>Exponential patterns may not contain grouping separators.
 * </ul>
 *
 * <a name="sigdig"><h4>
 * <strong><font face=helvetica color=red>NEW</font></strong>
 * Significant Digits</h4></a>
 *
 * <code>DecimalFormat</code> has two ways of controlling how many
 * digits are shows: (a) significant digits counts, or (b) integer and
 * fraction digit counts.  Integer and fraction digit counts are
 * described above.  When a formatter is using significant digits
 * counts, the number of integer and fraction digits is not specified
 * directly, and the formatter settings for these counts are ignored.
 * Instead, the formatter uses however many integer and fraction
 * digits are required to display the specified number of significant
 * digits.  Examples:
 *
 * <blockquote>
 * <table border=0 cellspacing=3 cellpadding=0>
 *   <tr bgcolor="#ccccff">
 *     <th align=left>Pattern
 *     <th align=left>Minimum significant digits
 *     <th align=left>Maximum significant digits
 *     <th align=left>Number
 *     <th align=left>Output of format()
 *   <tr valign=top>
 *     <td><code>@@@</code>
 *     <td>3
 *     <td>3
 *     <td>12345
 *     <td><code>12300</code>
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>@@@</code>
 *     <td>3
 *     <td>3
 *     <td>0.12345
 *     <td><code>0.123</code>
 *   <tr valign=top>
 *     <td><code>@@##</code>
 *     <td>2
 *     <td>4
 *     <td>3.14159
 *     <td><code>3.142</code>
 *   <tr valign=top bgcolor="#eeeeff">
 *     <td><code>@@##</code>
 *     <td>2
 *     <td>4
 *     <td>1.23004
 *     <td><code>1.23</code>
 * </table>
 * </blockquote>
 *
 * <ul>
 * <li>Significant digit counts may be expressed using patterns that
 * specify a minimum and maximum number of significant digits.  These
 * are indicated by the <code>'@'</code> and <code>'#'</code>
 * characters.  The minimum number of significant digits is the number
 * of <code>'@'</code> characters.  The maximum number of significant
 * digits is the number of <code>'@'</code> characters plus the number
 * of <code>'#'</code> characters following on the right.  For
 * example, the pattern <code>"@@@"</code> indicates exactly 3
 * significant digits.  The pattern <code>"@##"</code> indicates from
 * 1 to 3 significant digits.  Trailing zero digits to the right of
 * the decimal separator are suppressed after the minimum number of
 * significant digits have been shown.  For example, the pattern
 * <code>"@##"</code> formats the number 0.1203 as
 * <code>"0.12"</code>.
 *
 * <li>If a pattern uses significant digits, it may not contain a
 * decimal separator, nor the <code>'0'</code> pattern character.
 * Patterns such as <code>"@00"</code> or <code>"@.###"</code> are
 * disallowed.
 *
 * <li>Any number of <code>'#'</code> characters may be prepended to
 * the left of the leftmost <code>'@'</code> character.  These have no
 * effect on the minimum and maximum significant digits counts, but
 * may be used to position grouping separators.  For example,
 * <code>"#,#@#"</code> indicates a minimum of one significant digits,
 * a maximum of two significant digits, and a grouping size of three.
 *
 * <li>In order to enable significant digits formatting, use a pattern
 * containing the <code>'@'</code> pattern character.  Alternatively,
 * call {@link #setSignificantDigitsUsed setSignificantDigitsUsed(true)}.
 *
 * <li>In order to disable significant digits formatting, use a
 * pattern that does not contain the <code>'@'</code> pattern
 * character. Alternatively, call {@link #setSignificantDigitsUsed
 * setSignificantDigitsUsed(false)}.
 *
 * <li>The number of significant digits has no effect on parsing.
 *
 * <li>Significant digits may be used together with exponential notation. Such
 * patterns are equivalent to a normal exponential pattern with a minimum and
 * maximum integer digit count of one, a minimum fraction digit count of
 * <code>getMinimumSignificantDigits() - 1</code>, and a maximum fraction digit
 * count of <code>getMaximumSignificantDigits() - 1</code>. For example, the
 * pattern <code>"@@###E0"</code> is equivalent to <code>"0.0###E0"</code>.
 *
 * <li>If signficant digits are in use, then the integer and fraction
 * digit counts, as set via the API, are ignored.  If significant
 * digits are not in use, then the signficant digit counts, as set via
 * the API, are ignored.
 *
 * </ul>
 * 
 * <h4>
 * <strong><font face=helvetica color=red>NEW</font></strong>
 * Padding</h4>
 *
 * <p><code>DecimalFormat</code> supports padding the result of
 * {@link #format} to a specific width.  Padding may be specified either
 * through the API or through the pattern syntax.  In a pattern the pad escape
 * character, followed by a single pad character, causes padding to be parsed
 * and formatted.  The pad escape character is '*' in unlocalized patterns, and
 * can be localized using {@link DecimalFormatSymbols#setPadEscape}.  For
 * example, <code>"$*x#,##0.00"</code> formats 123 to <code>"$xx123.00"</code>,
 * and 1234 to <code>"$1,234.00"</code>.
 *
 * <ul>
 * <li>When padding is in effect, the width of the positive subpattern,
 * including prefix and suffix, determines the format width.  For example, in
 * the pattern <code>"* #0 o''clock"</code>, the format width is 10.
 *
 * <li>The width is counted in 16-bit code units (Java <code>char</code>s).
 *
 * <li>Some parameters which usually do not matter have meaning when padding is
 * used, because the pattern width is significant with padding.  In the pattern
 * "* ##,##,#,##0.##", the format width is 14.  The initial characters "##,##,"
 * do not affect the grouping size or maximum integer digits, but they do affect
 * the format width.
 *
 * <li>Padding may be inserted at one of four locations: before the prefix,
 * after the prefix, before the suffix, or after the suffix.  If padding is
 * specified in any other location, {@link #applyPattern} throws an {@link
 * IllegalArgumentException}.  If there is no prefix, before the
 * prefix and after the prefix are equivalent, likewise for the suffix.
 *
 * <li>When specified in a pattern, the 16-bit <code>char</code> immediately
 * following the pad escape is the pad character. This may be any character,
 * including a special pattern character. That is, the pad escape
 * <em>escapes</em> the following character. If there is no character after
 * the pad escape, then the pattern is illegal.
 *
 * </ul>
 *
 * <p>
 * <strong><font face=helvetica color=red>NEW</font></strong>
 * <strong>Rounding</strong>
 *
 * <p><code>DecimalFormat</code> supports rounding to a specific increment.  For
 * example, 1230 rounded to the nearest 50 is 1250.  1.234 rounded to the
 * nearest 0.65 is 1.3.  The rounding increment may be specified through the API
 * or in a pattern.  To specify a rounding increment in a pattern, include the
 * increment in the pattern itself.  "#,#50" specifies a rounding increment of
 * 50.  "#,##0.05" specifies a rounding increment of 0.05.
 *
 * <ul>
 * <li>Rounding only affects the string produced by formatting.  It does
 * not affect parsing or change any numerical values.
 *
 * <li>A <em>rounding mode</em> determines how values are rounded; see the
 * {@link com.ibm.icu.math.BigDecimal} documentation for a description of the
 * modes.  Rounding increments specified in patterns use the default mode,
 * {@link com.ibm.icu.math.BigDecimal#ROUND_HALF_EVEN}.
 *
 * <li>Some locales use rounding in their currency formats to reflect the
 * smallest currency denomination.
 *
 * <li>In a pattern, digits '1' through '9' specify rounding, but otherwise
 * behave identically to digit '0'.
 * </ul>
 *
 * <h4>Synchronization</h4>
 *
 * <p><code>DecimalFormat</code> objects are not synchronized.  Multiple
 * threads should not access one formatter concurrently.
 *
 * @see          java.text.Format
 * @see          NumberFormat
 * @author       Mark Davis
 * @author       Alan Liu
 * @stable ICU 2.0
 */
public class DecimalFormat extends NumberFormat {

    private static final long serialVersionUID = 1L;
    /**
     * @internal
     * @param delegate the NumberFormat to which to delegate
     */
    public DecimalFormat(java.text.DecimalFormat delegate) {
        super(delegate);
    }
        
    /**
     * Create a DecimalFormat using the default pattern and symbols
     * for the default locale. This is a convenient way to obtain a
     * DecimalFormat when internationalization is not the main concern.
     * <p>
     * To obtain standard formats for a given locale, use the factory methods
     * on NumberFormat such as getNumberInstance. These factories will
     * return the most appropriate sub-class of NumberFormat for a given
     * locale.
     * @see NumberFormat#getInstance
     * @see NumberFormat#getNumberInstance
     * @see NumberFormat#getCurrencyInstance
     * @see NumberFormat#getPercentInstance
     * @stable ICU 2.0
     */
    public DecimalFormat() {
        this(new java.text.DecimalFormat());
    }
        
    /**
     * Create a DecimalFormat from the given pattern and the symbols
     * for the default locale. This is a convenient way to obtain a
     * DecimalFormat when internationalization is not the main concern.
     * <p>
     * To obtain standard formats for a given locale, use the factory methods
     * on NumberFormat such as getNumberInstance. These factories will
     * return the most appropriate sub-class of NumberFormat for a given
     * locale.
     * @param pattern A non-localized pattern string.
     * @exception IllegalArgumentException if the given pattern is invalid.
     * @see NumberFormat#getInstance
     * @see NumberFormat#getNumberInstance
     * @see NumberFormat#getCurrencyInstance
     * @see NumberFormat#getPercentInstance
     * @stable ICU 2.0
     */
    public DecimalFormat(String pattern) {
        this(new java.text.DecimalFormat(pattern));
    }
        
        
    /**
     * Create a DecimalFormat from the given pattern and symbols.
     * Use this constructor when you need to completely customize the
     * behavior of the format.
     * <p>
     * To obtain standard formats for a given
     * locale, use the factory methods on NumberFormat such as
     * getInstance or getCurrencyInstance. If you need only minor adjustments
     * to a standard format, you can modify the format returned by
     * a NumberFormat factory method.
     * @param pattern a non-localized pattern string
     * @param symbols the set of symbols to be used
     * @exception IllegalArgumentException if the given pattern is invalid
     * @see NumberFormat#getInstance
     * @see NumberFormat#getNumberInstance
     * @see NumberFormat#getCurrencyInstance
     * @see NumberFormat#getPercentInstance
     * @see DecimalFormatSymbols
     * @stable ICU 2.0
     */
    public DecimalFormat(String pattern, DecimalFormatSymbols symbols) {
        this(new java.text.DecimalFormat(pattern, symbols.dfs));
    }
        
    /**
     * Returns a copy of the decimal format symbols used by this format.
     * @return desired DecimalFormatSymbols
     * @see DecimalFormatSymbols
     * @stable ICU 2.0
     */
    public DecimalFormatSymbols getDecimalFormatSymbols() {
        return new DecimalFormatSymbols(((java.text.DecimalFormat)numberFormat).getDecimalFormatSymbols());
    }
        
    /**
     * Sets the decimal format symbols used by this format.  The
     * format uses a copy of the provided symbols.
     * @param newSymbols desired DecimalFormatSymbols
     * @see DecimalFormatSymbols
     * @stable ICU 2.0
     */
    public void setDecimalFormatSymbols(DecimalFormatSymbols newSymbols) {
        ((java.text.DecimalFormat)numberFormat).setDecimalFormatSymbols(newSymbols.dfs);
    }
        
        
    /**
     * Get the positive prefix.
     * <P>Examples: +123, $123, sFr123
     * @stable ICU 2.0
     */
    public String getPositivePrefix() {
        return ((java.text.DecimalFormat)numberFormat).getPositivePrefix();
    }
        
    /**
     * Set the positive prefix.
     * <P>Examples: +123, $123, sFr123
     * @stable ICU 2.0
     */
    public void setPositivePrefix(String newValue) {
        ((java.text.DecimalFormat)numberFormat).setPositivePrefix(newValue);
    }
        
    /**
     * Get the negative prefix.
     * <P>Examples: -123, ($123) (with negative suffix), sFr-123
     * @stable ICU 2.0
     */
    public String getNegativePrefix () {
        return ((java.text.DecimalFormat)numberFormat).getNegativePrefix();
    }
        
    /**
     * Set the negative prefix.
     * <P>Examples: -123, ($123) (with negative suffix), sFr-123
     * @stable ICU 2.0
     */
    public void setNegativePrefix (String newValue) {
        ((java.text.DecimalFormat)numberFormat).setNegativePrefix(newValue);
    }
        
    /**
     * Get the positive suffix.
     * <P>Example: 123%
     * @stable ICU 2.0
     */
    public String getPositiveSuffix () {
        return ((java.text.DecimalFormat)numberFormat).getPositiveSuffix();
    }
        
    /**
     * Set the positive suffix.
     * <P>Example: 123%
     * @stable ICU 2.0
     */
    public void setPositiveSuffix (String newValue) {
        ((java.text.DecimalFormat)numberFormat).setPositiveSuffix(newValue);
    }
        
    /**
     * Get the negative suffix.
     * <P>Examples: -123%, ($123) (with positive suffixes)
     * @stable ICU 2.0
     */
    public String getNegativeSuffix () {
        return ((java.text.DecimalFormat)numberFormat).getNegativeSuffix();
    }
        
    /**
     * Set the positive suffix.
     * <P>Examples: 123%
     * @stable ICU 2.0
     */
    public void setNegativeSuffix (String newValue) {
        ((java.text.DecimalFormat)numberFormat).setNegativeSuffix(newValue);
    }
        
    /**
     * Get the multiplier for use in percent, permill, etc.
     * For a percentage, set the suffixes to have "%" and the multiplier to be 100.
     * (For Arabic, use arabic percent symbol).
     * For a permill, set the suffixes to have "\u2031" and the multiplier to be 1000.
     * <P>Examples: with 100, 1.23 -> "123", and "123" -> 1.23
     * @stable ICU 2.0
     */
    public int getMultiplier () {
        return ((java.text.DecimalFormat)numberFormat).getMultiplier();
    }
        
    /**
     * Set the multiplier for use in percent, permill, etc.
     * For a percentage, set the suffixes to have "%" and the multiplier to be 100.
     * (For Arabic, use arabic percent symbol).
     * For a permill, set the suffixes to have "\u2031" and the multiplier to be 1000.
     * <P>Examples: with 100, 1.23 -> "123", and "123" -> 1.23
     * @stable ICU 2.0
     */
    public void setMultiplier (int newValue) {
        ((java.text.DecimalFormat)numberFormat).setMultiplier(newValue);
    }
        
    /**
     * Return the grouping size. Grouping size is the number of digits between
     * grouping separators in the integer portion of a number.  For example,
     * in the number "123,456.78", the grouping size is 3.
     * @see #setGroupingSize
     * @see NumberFormat#isGroupingUsed
     * @see DecimalFormatSymbols#getGroupingSeparator
     * @stable ICU 2.0
     */
    public int getGroupingSize () {
        return ((java.text.DecimalFormat)numberFormat).getGroupingSize();
    }
        
    /**
     * Set the grouping size. Grouping size is the number of digits between
     * grouping separators in the integer portion of a number.  For example,
     * in the number "123,456.78", the grouping size is 3.
     * @see #getGroupingSize
     * @see NumberFormat#setGroupingUsed
     * @see DecimalFormatSymbols#setGroupingSeparator
     * @stable ICU 2.0
     */
    public void setGroupingSize (int newValue) {
        ((java.text.DecimalFormat)numberFormat).setGroupingSize(newValue);
    }
        
    /**
     * Allows you to get the behavior of the decimal separator with integers.
     * (The decimal separator will always appear with decimals.)
     * <P>Example: Decimal ON: 12345 -> 12345.; OFF: 12345 -> 12345
     * @stable ICU 2.0
     */
    public boolean isDecimalSeparatorAlwaysShown() {
        return ((java.text.DecimalFormat)numberFormat).isDecimalSeparatorAlwaysShown();
    }
        
    /**
     * Allows you to set the behavior of the decimal separator with integers.
     * (The decimal separator will always appear with decimals.)
     *
     * <p>This only affects formatting, and only where
     * there might be no digits after the decimal point, e.g.,
     * if true,  3456.00 -> "3,456."
     * if false, 3456.00 -> "3456"
     * This is independent of parsing.  If you want parsing to stop at the decimal
     * point, use setParseIntegerOnly.
     *
     * <P>Example: Decimal ON: 12345 -> 12345.; OFF: 12345 -> 12345
     * @stable ICU 2.0
     */
    public void setDecimalSeparatorAlwaysShown(boolean newValue) {
        ((java.text.DecimalFormat)numberFormat).setDecimalSeparatorAlwaysShown(newValue);
    }
        
    /**
     * Standard override; no change in semantics.
     * @stable ICU 2.0
     */
    public Object clone() {
        return new DecimalFormatSymbols((java.text.DecimalFormatSymbols)numberFormat.clone());
    }
        
    /**
     * Synthesizes a pattern string that represents the current state
     * of this Format object.
     * @see #applyPattern
     * @stable ICU 2.0
     */
    public String toPattern() {
        return ((java.text.DecimalFormat)numberFormat).toPattern();
    }
        
    /**
     * Synthesizes a localized pattern string that represents the current
     * state of this Format object.
     * @see #applyPattern
     * @stable ICU 2.0
     */
    public String toLocalizedPattern() {
        return ((java.text.DecimalFormat)numberFormat).toLocalizedPattern();
    }
        
        
    /**
     * Apply the given pattern to this Format object.  A pattern is a
     * short-hand specification for the various formatting properties.
     * These properties can also be changed individually through the
     * various setter methods.
     * <p>
     * There is no limit to integer digits are set
     * by this routine, since that is the typical end-user desire;
     * use setMaximumInteger if you want to set a real value.
     * For negative numbers, use a second pattern, separated by a semicolon
     * <P>Example "#,#00.0#" -> 1,234.56
     * <P>This means a minimum of 2 integer digits, 1 fraction digit, and
     * a maximum of 2 fraction digits.
     * <p>Example: "#,#00.0#;(#,#00.0#)" for negatives in parentheses.
     * <p>In negative patterns, the minimum and maximum counts are ignored;
     * these are presumed to be set in the positive pattern.
     * @stable ICU 2.0
     */
    public void applyPattern(String pattern) {
        ((java.text.DecimalFormat)numberFormat).applyPattern(pattern);
    }
        
    /**
     * Apply the given pattern to this Format object.  The pattern
     * is assumed to be in a localized notation. A pattern is a
     * short-hand specification for the various formatting properties.
     * These properties can also be changed individually through the
     * various setter methods.
     * <p>
     * There is no limit to integer digits are set
     * by this routine, since that is the typical end-user desire;
     * use setMaximumInteger if you want to set a real value.
     * For negative numbers, use a second pattern, separated by a semicolon
     * <P>Example "#,#00.0#" -> 1,234.56
     * <P>This means a minimum of 2 integer digits, 1 fraction digit, and
     * a maximum of 2 fraction digits.
     * <p>Example: "#,#00.0#;(#,#00.0#)" for negatives in parentheses.
     * <p>In negative patterns, the minimum and maximum counts are ignored;
     * these are presumed to be set in the positive pattern.
     * @stable ICU 2.0
     */
    public void applyLocalizedPattern(String pattern) {
        ((java.text.DecimalFormat)numberFormat).applyLocalizedPattern(pattern);
    }
}