- * A MessageFormat produces concatenated messages in a
- * language-neutral way. It should be used for all string
- * concatenations that are visible to end users.
- * <P>
- * A MessageFormat contains an array of <EM>subformats</EM> arranged
- * within a <EM>template string</EM>. Together, the subformats and
- * template string determine how the MessageFormat will operate during
- * formatting and parsing.
- * <P>
- * Typically, both the subformats and the template string are
- * specified at once in a <EM>pattern</EM>. By using different
- * patterns for different locales, messages may be localized.
- * <P>
- * During formatting, the MessageFormat takes an array of arguments
- * and produces a user-readable string. Each argument is a
- * Formattable object; they may be passed in in an array, or as a
- * single Formattable object which itself contains an array. Each
- * argument is matched up with its corresponding subformat, which then
- * formats it into a string. The resultant strings are then assembled
- * within the string template of the MessageFormat to produce the
- * final output string.
- * <P>
- * During parsing, an input string is matched against the string
- * template of the MessageFormat to produce an array of Formattable
- * objects. Plain text of the template string is matched directly
- * against intput text. At each position in the template string where
- * a subformat is located, the subformat is called to parse the
- * corresponding segment of input text to produce an output argument.
- * In this way, an array of arguments is created which together
- * constitute the parse result.
- * <P>
- * Parsing may fail or produce unexpected results in a number of
- * circumstances.
- * <UL>
- * <LI>If one of the arguments does not occur in the pattern, it
- * will be returned as a default Formattable.
- * <LI>If the format of an argument is loses information, such as with
- * a choice format where a large number formats to "many", then the
- * parse may not correspond to the originally formatted argument.
- * <LI>MessageFormat does not handle ChoiceFormat recursion during
- * parsing; such parses will fail.
- * <LI>Parsing will not always find a match (or the correct match) if
- * some part of the parse is ambiguous. For example, if the pattern
- * "{1},{2}" is used with the string arguments {"a,b", "c"}, it will
- * format as "a,b,c". When the result is parsed, it will return {"a",
- * "b,c"}.
- * <LI>If a single argument is formatted more than once in the string,
- * then the rightmost subformat in the pattern string will produce the
- * parse result; prior subformats with the same argument index will
- * have no effect.
- * </UL>
- * Here are some examples of usage:
- * <P>
+ * <p>MessageFormat prepares strings for display to users,
+ * with optional arguments (variables/placeholders).
+ * The arguments can occur in any order, which is necessary for translation
+ * into languages with different grammars.
+ *
+ * <p>A MessageFormat is constructed from a <em>pattern</em> string
+ * with arguments in {curly braces} which will be replaced by formatted values.
+ *
+ * <p><code>MessageFormat</code> differs from the other <code>Format</code>
+ * classes in that you create a <code>MessageFormat</code> object with one
+ * of its constructors (not with a <code>createInstance</code> style factory
+ * method). Factory methods aren't necessary because <code>MessageFormat</code>
+ * itself doesn't implement locale-specific behavior. Any locale-specific
+ * behavior is defined by the pattern that you provide and the
+ * subformats used for inserted arguments.
+ *
+ * <p>Arguments can be named (using identifiers) or numbered (using small ASCII-digit integers).
+ * Some of the API methods work only with argument numbers and throw an exception
+ * if the pattern has named arguments (see {@link #usesNamedArguments()}).
+ *
+ * <p>An argument might not specify any format type. In this case,
+ * a Number value is formatted with a default (for the locale) NumberFormat,
+ * a Date value is formatted with a default (for the locale) DateFormat,
+ * and for any other value its toString() value is used.
+ *
+ * <p>An argument might specify a "simple" type for which the specified
+ * Format object is created, cached and used.
+ *
+ * <p>An argument might have a "complex" type with nested MessageFormat sub-patterns.
+ * During formatting, one of these sub-messages is selected according to the argument value
+ * and recursively formatted.
+ *
+ * <p>After construction, a custom Format object can be set for
+ * a top-level argument, overriding the default formatting and parsing behavior
+ * for that argument.
+ * However, custom formatting can be achieved more simply by writing
+ * a typeless argument in the pattern string
+ * and supplying it with a preformatted string value.
+ *
+ * <p>When formatting, MessageFormat takes a collection of argument values
+ * and writes an output string.
+ * The argument values may be passed as an array
+ * (when the pattern contains only numbered arguments)
+ * or as an array of names and and an array of arguments (which works for both named
+ * and numbered arguments).
+ *
+ * <p>Each argument is matched with one of the input values by array index or argument name
+ * and formatted according to its pattern specification
+ * (or using a custom Format object if one was set).
+ * A numbered pattern argument is matched with an argument name that contains that number
+ * as an ASCII-decimal-digit string (without leading zero).
+ *
+ * <h4><a name="patterns">Patterns and Their Interpretation</a></h4>
+ *
+ * <code>MessageFormat</code> uses patterns of the following form:
+ * <pre>
+ * message = messageText (argument messageText)*
+ * argument = noneArg | simpleArg | complexArg
+ * complexArg = choiceArg | pluralArg | selectArg | selectordinalArg
+ *
+ * noneArg = '{' argNameOrNumber '}'
+ * simpleArg = '{' argNameOrNumber ',' argType [',' argStyle] '}'
+ * choiceArg = '{' argNameOrNumber ',' "choice" ',' choiceStyle '}'
+ * pluralArg = '{' argNameOrNumber ',' "plural" ',' pluralStyle '}'
+ * selectArg = '{' argNameOrNumber ',' "select" ',' selectStyle '}'
+ * selectordinalArg = '{' argNameOrNumber ',' "selectordinal" ',' pluralStyle '}'
+ *
+ * choiceStyle: see {@link ChoiceFormat}
+ * pluralStyle: see {@link PluralFormat}
+ * selectStyle: see {@link SelectFormat}
+ *
+ * argNameOrNumber = argName | argNumber
+ * argName = [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
+ * argNumber = '0' | ('1'..'9' ('0'..'9')*)
+ *
+ * argType = "number" | "date" | "time" | "spellout" | "ordinal" | "duration"
+ * argStyle = "short" | "medium" | "long" | "full" | "integer" | "currency" | "percent" | argStyleText
+ * </pre>
+ *
+ * <ul>
+ * <li>messageText can contain quoted literal strings including syntax characters.
+ * A quoted literal string begins with an ASCII apostrophe and a syntax character
+ * (usually a {curly brace}) and continues until the next single apostrophe.
+ * A double ASCII apostrohpe inside or outside of a quoted string represents
+ * one literal apostrophe.
+ * <li>Quotable syntax characters are the {curly braces} in all messageText parts,
+ * plus the '#' sign in a messageText immediately inside a pluralStyle,
+ * and the '|' symbol in a messageText immediately inside a choiceStyle.
+ * <li>See also {@link #UMessagePatternApostropheMode}
+ * <li>In argStyleText, every single ASCII apostrophe begins and ends quoted literal text,
+ * and unquoted {curly braces} must occur in matched pairs.
+ * </ul>
+ *
+ * <p>Recommendation: Use the real apostrophe (single quote) character
+ * \htmlonly’\endhtmlonly (U+2019) for
+ * human-readable text, and use the ASCII apostrophe ' (U+0027)
+ * only in program syntax, like quoting in MessageFormat.
+ * See the annotations for U+0027 Apostrophe in The Unicode Standard.
+ *
+ * <p>The <code>choice</code> argument type is deprecated.
+ * Use <code>plural</code> arguments for proper plural selection,
+ * and <code>select</code> arguments for simple selection among a fixed set of choices.
+ *
+ * <p>The <code>argType</code> and <code>argStyle</code> values are used to create
+ * a <code>Format</code> instance for the format element. The following
+ * table shows how the values map to Format instances. Combinations not
+ * shown in the table are illegal. Any <code>argStyleText</code> must
+ * be a valid pattern string for the Format subclass used.
+ *
+ * <p><table border=1>
+ * <tr>
+ * <th>argType
+ * <th>argStyle
+ * <th>resulting Format object
+ * <tr>
+ * <td colspan=2><i>(none)</i>
+ * <td><code>null</code>
+ * <tr>
+ * <td rowspan=5><code>number</code>
+ * <td><i>(none)</i>
+ * <td><code>NumberFormat.createInstance(getLocale(), status)</code>
+ * <tr>
+ * <td><code>integer</code>
+ * <td><code>NumberFormat.createInstance(getLocale(), kNumberStyle, status)</code>
+ * <tr>
+ * <td><code>currency</code>
+ * <td><code>NumberFormat.createCurrencyInstance(getLocale(), status)</code>
+ * <tr>
+ * <td><code>percent</code>
+ * <td><code>NumberFormat.createPercentInstance(getLocale(), status)</code>
+ * <tr>
+ * <td><i>argStyleText</i>
+ * <td><code>new DecimalFormat(argStyleText, new DecimalFormatSymbols(getLocale(), status), status)</code>
+ * <tr>
+ * <td rowspan=6><code>date</code>
+ * <td><i>(none)</i>
+ * <td><code>DateFormat.createDateInstance(kDefault, getLocale(), status)</code>
+ * <tr>
+ * <td><code>short</code>
+ * <td><code>DateFormat.createDateInstance(kShort, getLocale(), status)</code>
+ * <tr>
+ * <td><code>medium</code>
+ * <td><code>DateFormat.createDateInstance(kDefault, getLocale(), status)</code>
+ * <tr>
+ * <td><code>long</code>
+ * <td><code>DateFormat.createDateInstance(kLong, getLocale(), status)</code>
+ * <tr>
+ * <td><code>full</code>
+ * <td><code>DateFormat.createDateInstance(kFull, getLocale(), status)</code>
+ * <tr>
+ * <td><i>argStyleText</i>
+ * <td><code>new SimpleDateFormat(argStyleText, getLocale(), status)
+ * <tr>
+ * <td rowspan=6><code>time</code>
+ * <td><i>(none)</i>
+ * <td><code>DateFormat.createTimeInstance(kDefault, getLocale(), status)</code>
+ * <tr>
+ * <td><code>short</code>
+ * <td><code>DateFormat.createTimeInstance(kShort, getLocale(), status)</code>
+ * <tr>
+ * <td><code>medium</code>
+ * <td><code>DateFormat.createTimeInstance(kDefault, getLocale(), status)</code>
+ * <tr>
+ * <td><code>long</code>
+ * <td><code>DateFormat.createTimeInstance(kLong, getLocale(), status)</code>
+ * <tr>
+ * <td><code>full</code>
+ * <td><code>DateFormat.createTimeInstance(kFull, getLocale(), status)</code>
+ * <tr>
+ * <td><i>argStyleText</i>
+ * <td><code>new SimpleDateFormat(argStyleText, getLocale(), status)
+ * <tr>
+ * <td><code>spellout</code>
+ * <td><i>argStyleText (optional)</i>
+ * <td><code>new RuleBasedNumberFormat(URBNF_SPELLOUT, getLocale(), status)
+ * <br/> .setDefaultRuleset(argStyleText, status);</code>
+ * <tr>
+ * <td><code>ordinal</code>
+ * <td><i>argStyleText (optional)</i>
+ * <td><code>new RuleBasedNumberFormat(URBNF_ORDINAL, getLocale(), status)
+ * <br/> .setDefaultRuleset(argStyleText, status);</code>
+ * <tr>
+ * <td><code>duration</code>
+ * <td><i>argStyleText (optional)</i>
+ * <td><code>new RuleBasedNumberFormat(URBNF_DURATION, getLocale(), status)
+ * <br/> .setDefaultRuleset(argStyleText, status);</code>
+ * </table>
+ * <p>
+ *
+ * <h4>Usage Information</h4>
+ *
+ * <p>Here are some examples of usage:
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