Class MessageFormat

Constructor Detail

• MessageFormat

  public MessageFormat(String pattern)

  Constructs a MessageFormat for the default locale and the specified pattern. The constructor first sets the locale, then parses the pattern and creates a list of subformats for the format elements contained in it. Patterns and their interpretation are specified in the class description.

  Parameters:

  pattern - the pattern for this message format

  Throws:

  IllegalArgumentException - if the pattern is invalid

• MessageFormat

  public MessageFormat(String pattern,
               Locale locale)

  Constructs a MessageFormat for the specified locale and pattern. The constructor first sets the locale, then parses the pattern and creates a list of subformats for the format elements contained in it. Patterns and their interpretation are specified in the class description.

  Parameters:

  pattern - the pattern for this message format

  locale - the locale for this message format

  Throws:

  IllegalArgumentException - if the pattern is invalid

  Since:

  1.4

Method Detail

• setLocale

  public void setLocale(Locale locale)

  Sets the locale to be used when creating or comparing subformats. This affects subsequent calls

  • to the applyPattern and toPattern methods if format elements specify a format type and therefore have the subformats created in the applyPattern method, as well as
  • to the format and formatToCharacterIterator methods if format elements do not specify a format type and therefore have the subformats created in the formatting methods.

  Subformats that have already been created are not affected.

  Parameters:

  locale - the locale to be used when creating or comparing subformats

• getLocale

  public Locale getLocale()

  Gets the locale that's used when creating or comparing subformats.

  Returns:

  the locale used when creating or comparing subformats

• applyPattern

  public void applyPattern(String pattern)

  Sets the pattern used by this message format. The method parses the pattern and creates a list of subformats for the format elements contained in it. Patterns and their interpretation are specified in the class description.

  Parameters:

  pattern - the pattern for this message format

  Throws:

  IllegalArgumentException - if the pattern is invalid

• toPattern

  public String toPattern()

  Returns a pattern representing the current state of the message format. The string is constructed from internal information and therefore does not necessarily equal the previously applied pattern.

  Returns:

  a pattern representing the current state of the message format

• setFormatsByArgumentIndex

  public void setFormatsByArgumentIndex(Format[] newFormats)

  Sets the formats to use for the values passed into format methods or returned from parse methods. The indices of elements in newFormats correspond to the argument indices used in the previously set pattern string. The order of formats in newFormats thus corresponds to the order of elements in the arguments array passed to the format methods or the result array returned by the parse methods.

  If an argument index is used for more than one format element in the pattern string, then the corresponding new format is used for all such format elements. If an argument index is not used for any format element in the pattern string, then the corresponding new format is ignored. If fewer formats are provided than needed, then only the formats for argument indices less than newFormats.length are replaced.

  Parameters:

  newFormats - the new formats to use

  Throws:

  NullPointerException - if newFormats is null

  Since:

  1.4

• setFormats

  public void setFormats(Format[] newFormats)

  Sets the formats to use for the format elements in the previously set pattern string. The order of formats in newFormats corresponds to the order of format elements in the pattern string.

  If more formats are provided than needed by the pattern string, the remaining ones are ignored. If fewer formats are provided than needed, then only the first newFormats.length formats are replaced.

  Since the order of format elements in a pattern string often changes during localization, it is generally better to use the setFormatsByArgumentIndex method, which assumes an order of formats corresponding to the order of elements in the arguments array passed to the format methods or the result array returned by the parse methods.

  Parameters:

  newFormats - the new formats to use

  Throws:

  NullPointerException - if newFormats is null

• setFormatByArgumentIndex

  public void setFormatByArgumentIndex(int argumentIndex,
                              Format newFormat)

  Sets the format to use for the format elements within the previously set pattern string that use the given argument index. The argument index is part of the format element definition and represents an index into the arguments array passed to the format methods or the result array returned by the parse methods.

  If the argument index is used for more than one format element in the pattern string, then the new format is used for all such format elements. If the argument index is not used for any format element in the pattern string, then the new format is ignored.

  Parameters:

  argumentIndex - the argument index for which to use the new format

  newFormat - the new format to use

  Since:

  1.4

• setFormat

  public void setFormat(int formatElementIndex,
               Format newFormat)

  Sets the format to use for the format element with the given format element index within the previously set pattern string. The format element index is the zero-based number of the format element counting from the start of the pattern string.

  Since the order of format elements in a pattern string often changes during localization, it is generally better to use the setFormatByArgumentIndex method, which accesses format elements based on the argument index they specify.

  Parameters:

  formatElementIndex - the index of a format element within the pattern

  newFormat - the format to use for the specified format element

  Throws:

  ArrayIndexOutOfBoundsException - if formatElementIndex is equal to or larger than the number of format elements in the pattern string

• getFormatsByArgumentIndex

  public Format[] getFormatsByArgumentIndex()

  Gets the formats used for the values passed into format methods or returned from parse methods. The indices of elements in the returned array correspond to the argument indices used in the previously set pattern string. The order of formats in the returned array thus corresponds to the order of elements in the arguments array passed to the format methods or the result array returned by the parse methods.

  If an argument index is used for more than one format element in the pattern string, then the format used for the last such format element is returned in the array. If an argument index is not used for any format element in the pattern string, then null is returned in the array.

  Returns:

  the formats used for the arguments within the pattern

  Since:

  1.4

• getFormats

  public Format[] getFormats()

  Gets the formats used for the format elements in the previously set pattern string. The order of formats in the returned array corresponds to the order of format elements in the pattern string.

  Since the order of format elements in a pattern string often changes during localization, it's generally better to use the getFormatsByArgumentIndex method, which assumes an order of formats corresponding to the order of elements in the arguments array passed to the format methods or the result array returned by the parse methods.

  Returns:

  the formats used for the format elements in the pattern

• format

  public final StringBuffer format(Object[] arguments,
                    StringBuffer result,
                    FieldPosition pos)

  Formats an array of objects and appends the MessageFormat's pattern, with format elements replaced by the formatted objects, to the provided StringBuffer.

  The text substituted for the individual format elements is derived from the current subformat of the format element and the arguments element at the format element's argument index as indicated by the first matching line of the following table. An argument is unavailable if arguments is null or has fewer than argumentIndex+1 elements.

  Subformat	Argument	Formatted Text
  any	unavailable	"{" + argumentIndex + "}"
  any	null	"null"
  instanceof ChoiceFormat	any	subformat.format(argument).indexOf('{') >= 0 ? (new MessageFormat(subformat.format(argument), getLocale())).format(argument) : subformat.format(argument)
  != null	any	subformat.format(argument)
  null	instanceof Number	NumberFormat.getInstance(getLocale()).format(argument)
  null	instanceof Date	DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, getLocale()).format(argument)
  null	instanceof String	argument
  null	any	argument.toString()

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  If pos is non-null, and refers to Field.ARGUMENT, the location of the first formatted string will be returned.

  Parameters:

  arguments - an array of objects to be formatted and substituted.

  result - where text is appended.

  pos - On input: an alignment field, if desired. On output: the offsets of the alignment field.

  Throws:

  IllegalArgumentException - if an argument in the arguments array is not of the type expected by the format element(s) that use it.

• format

  public static String format(String pattern,
              Object... arguments)

  Creates a MessageFormat with the given pattern and uses it to format the given arguments. This is equivalent to

  (new MessageFormat(pattern)).format(arguments, new StringBuffer(), null).toString()

  Throws:

  IllegalArgumentException - if the pattern is invalid, or if an argument in the arguments array is not of the type expected by the format element(s) that use it.

• format

  public final StringBuffer format(Object arguments,
                    StringBuffer result,
                    FieldPosition pos)

  Formats an array of objects and appends the MessageFormat's pattern, with format elements replaced by the formatted objects, to the provided StringBuffer. This is equivalent to

  format((Object[]) arguments, result, pos)

  Specified by:

  format in class Format

  Parameters:

  arguments - an array of objects to be formatted and substituted.

  result - where text is appended.

  pos - On input: an alignment field, if desired. On output: the offsets of the alignment field.

  Returns:

  the string buffer passed in as toAppendTo, with formatted text appended

  Throws:

  IllegalArgumentException - if an argument in the arguments array is not of the type expected by the format element(s) that use it.

• formatToCharacterIterator

  public AttributedCharacterIterator formatToCharacterIterator(Object arguments)

  Formats an array of objects and inserts them into the MessageFormat's pattern, producing an AttributedCharacterIterator. You can use the returned AttributedCharacterIterator to build the resulting String, as well as to determine information about the resulting String.

  The text of the returned AttributedCharacterIterator is the same that would be returned by

  format(arguments, new StringBuffer(), null).toString()

  In addition, the AttributedCharacterIterator contains at least attributes indicating where text was generated from an argument in the arguments array. The keys of these attributes are of type MessageFormat.Field, their values are Integer objects indicating the index in the arguments array of the argument from which the text was generated.

  The attributes/value from the underlying Format instances that MessageFormat uses will also be placed in the resulting AttributedCharacterIterator. This allows you to not only find where an argument is placed in the resulting String, but also which fields it contains in turn.

  Overrides:

  formatToCharacterIterator in class Format

  Parameters:

  arguments - an array of objects to be formatted and substituted.

  Returns:

  AttributedCharacterIterator describing the formatted value.

  Throws:

  NullPointerException - if arguments is null.

  IllegalArgumentException - if an argument in the arguments array is not of the type expected by the format element(s) that use it.

  Since:

  1.4

• parse

  public Object[] parse(String source,
               ParsePosition pos)

  Parses the string.

  Caveats: The parse may fail in a number of circumstances. For example:

  • If one of the arguments does not occur in the pattern.
  • If the format of an argument loses information, such as with a choice format where a large number formats to "many".
  • Does not yet handle recursion (where the substituted strings contain {n} references.)
  • 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"}.
  • If a single argument is parsed more than once in the string, then the later parse wins.

  When the parse fails, use ParsePosition.getErrorIndex() to find out where in the string the parsing failed. The returned error index is the starting offset of the sub-patterns that the string is comparing with. For example, if the parsing string "AAA {0} BBB" is comparing against the pattern "AAD {0} BBB", the error index is 0. When an error occurs, the call to this method will return null. If the source is null, return an empty array.

• parse

  public Object[] parse(String source)
                 throws ParseException

  Parses text from the beginning of the given string to produce an object array. The method may not use the entire text of the given string.

  See the parse(String, ParsePosition) method for more information on message parsing.

  Parameters:

  source - A String whose beginning should be parsed.

  Returns:

  An Object array parsed from the string.

  Throws:

  ParseException - if the beginning of the specified string cannot be parsed.

• parseObject

  public Object parseObject(String source,
                   ParsePosition pos)

  Parses text from a string to produce an object array.

  The method attempts to parse text starting at the index given by pos. If parsing succeeds, then the index of pos is updated to the index after the last character used (parsing does not necessarily use all characters up to the end of the string), and the parsed object array is returned. The updated pos can be used to indicate the starting point for the next call to this method. If an error occurs, then the index of pos is not changed, the error index of pos is set to the index of the character where the error occurred, and null is returned.

  See the parse(String, ParsePosition) method for more information on message parsing.

  Specified by:

  parseObject in class Format

  Parameters:

  source - A String, part of which should be parsed.

  pos - A ParsePosition object with index and error index information as described above.

  Returns:

  An Object array parsed from the string. In case of error, returns null.

  Throws:

  NullPointerException - if pos is null.

• clone

  public Object clone()

  Creates and returns a copy of this object.

  Overrides:

  clone in class Format

  Returns:

  a clone of this instance.

  See Also:

  Cloneable

• equals

  public boolean equals(Object obj)

  Equality comparison between two message format objects

  Overrides:

  equals in class Object

  Parameters:

  obj - the reference object with which to compare.

  Returns:

  true if this object is the same as the obj argument; false otherwise.

  See Also:

  Object.hashCode(), HashMap

• hashCode

  public int hashCode()

  Generates a hash code for the message format object.

  Overrides:

  hashCode in class Object

  Returns:

  a hash code value for this object.

  See Also:

  Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)