# MessageFormat

public class **MessageFormat** extends [Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html)  
`MessageFormat` provides a means to produce concatenated
messages in a language-neutral way. Use this to construct messages
displayed for end users.


`MessageFormat` takes a set of objects, formats them, then
inserts the formatted strings into the pattern at the appropriate places.


**Note:**
`MessageFormat` differs from the other `Format`
classes in that you create a `MessageFormat` object with one
of its constructors (not with a `getInstance` style factory
method). The factory methods aren't necessary because `MessageFormat`
itself doesn't implement locale specific behavior. Any locale specific
behavior is defined by the pattern that you provide as well as the
subformats used for inserted arguments.

### Patterns and Their Interpretation

`MessageFormat` uses patterns of the following form:
>
> ```
>  MessageFormatPattern:
>          String
>          MessageFormatPattern FormatElement String
>
>  FormatElement:
>          { ArgumentIndex }
>          { ArgumentIndex , FormatType }
>          { ArgumentIndex , FormatType , FormatStyle }
>
>  FormatType: one of 
>          number date time choice
>
>  FormatStyle:
>          short
>          medium
>          long
>          full
>          integer
>          currency
>          percent
>          SubformatPattern
>  
> ```

Within a *String*, a pair of single quotes can be used to
quote any arbitrary characters except single quotes. For example,
pattern string `"'{0}'"` represents string
`"{0}"`, not a *FormatElement*. A single quote itself
must be represented by doubled single quotes `''` throughout a
*String*. For example, pattern string `"'{''}'"` is
interpreted as a sequence of `'{` (start of quoting and a
left curly brace), `''` (a single quote), and
`}'` (a right curly brace and end of quoting),
*not* `'{'` and `'}'` (quoted left and
right curly braces): representing string `"{'}"`,
*not* `"{}"`.

A *SubformatPattern* is interpreted by its corresponding
subformat, and subformat-dependent pattern rules apply. For example,
pattern string `"{1,number,$'#',##}"`
(*SubformatPattern* with underline) will produce a number format
with the pound-sign quoted, with a result such as: `"$#31,45"`. Refer to each `Format` subclass documentation for
details.

Any unmatched quote is treated as closed at the end of the given
pattern. For example, pattern string `"'{0}"` is treated as
pattern `"'{0}'"`.

Any curly braces within an unquoted pattern must be balanced. For
example, `"ab {0} de"` and `"ab '}' de"` are
valid patterns, but `"ab {0'}' de"`, `"ab } de"`
and `"''{''"` are not.

**Warning:**
:   The rules for using quotes within message
    format patterns unfortunately have shown to be somewhat confusing.
    In particular, it isn't always obvious to localizers whether single
    quotes need to be doubled or not. Make sure to inform localizers about
    the rules, and tell them (for example, by using comments in resource
    bundle source files) which strings will be processed by `MessageFormat`.
    Note that localizers may need to use single quotes in translated
    strings where the original version doesn't have them.


The *ArgumentIndex* value is a non-negative integer written
using the digits `'0'` through `'9'`, and represents an index into the
`arguments` array passed to the `format` methods
or the result array returned by the `parse` methods.


The *FormatType* and *FormatStyle* values are used to create
a `Format` instance for the format element. The following
table shows how the values map to `Format` instances. Combinations not
shown in the table are illegal. A *SubformatPattern* must
be a valid pattern string for the `Format` subclass used.

| FormatType | FormatStyle | Subformat Created |
|---|---|---|
| *(none)* | *(none)* | `null` |
| `number` | *(none)* | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/NumberFormat.html#getInstance(java.util.Locale)``(getLocale())` |
| `number` | `integer` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/NumberFormat.html#getIntegerInstance(java.util.Locale)``(getLocale())` |
| `number` | `currency` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/NumberFormat.html#getCurrencyInstance(java.util.Locale)``(getLocale())` |
| `number` | `percent` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/NumberFormat.html#getPercentInstance(java.util.Locale)``(getLocale())` |
| `number` | *SubformatPattern* | `new` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DecimalFormat.html#DecimalFormat(java.lang.String,%20java.text.DecimalFormatSymbols)``(subformatPattern,` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DecimalFormatSymbols.html#getInstance(java.util.Locale)``(getLocale()))` |
| `date` | *(none)* | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getDateInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#DEFAULT``, getLocale())` |
| `date` | `short` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getDateInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#SHORT``, getLocale())` |
| `date` | `medium` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getDateInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#DEFAULT``, getLocale())` |
| `date` | `long` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getDateInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#LONG``, getLocale())` |
| `date` | `full` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getDateInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#FULL``, getLocale())` |
| `date` | *SubformatPattern* | `new` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/SimpleDateFormat.html#SimpleDateFormat(java.lang.String,%20java.util.Locale)``(subformatPattern, getLocale())` |
| `time` | *(none)* | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getTimeInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#DEFAULT``, getLocale())` |
| `time` | `short` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getTimeInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#SHORT``, getLocale())` |
| `time` | `medium` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getTimeInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#DEFAULT``, getLocale())` |
| `time` | `long` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getTimeInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#LONG``, getLocale())` |
| `time` | `full` | `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#getTimeInstance(int,%20java.util.Locale)``(``https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html#FULL``, getLocale())` |
| `time` | *SubformatPattern* | `new` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/SimpleDateFormat.html#SimpleDateFormat(java.lang.String,%20java.util.Locale)``(subformatPattern, getLocale())` |
| `choice` | *SubformatPattern* | `new` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ChoiceFormat.html#ChoiceFormat(java.lang.String)``(subformatPattern)` |

#### Usage Information


Here are some examples of usage.
In real internationalized programs, the message format pattern and other
static strings will, of course, be obtained from resource bundles.
Other parameters will be dynamically determined at runtime.


The first example uses the static method `MessageFormat.format`,
which internally creates a `MessageFormat` for one-time use:
>
> ```
>  int planet = 7;
>  String event = "a disturbance in the Force";
>
>  String result = MessageFormat.format(
>      "At {1,time} on {1,date}, there was {2} on planet {0,number,integer}.",
>      planet, new Date(), event);
>  
> ```
The output is:
>
> ```
>  At 12:30 PM on Jul 3, 2053, there was a disturbance in the Force on planet 7.
>  
> ```


The following example creates a `MessageFormat` instance that
can be used repeatedly:
>
> ```
>  int fileCount = 1273;
>  String diskName = "MyDisk";
>  Object[] testArgs = {new Long(fileCount), diskName};
>
>  MessageFormat form = new MessageFormat(
>      "The disk \"{1}\" contains {0} file(s).");
>
>  System.out.println(form.format(testArgs));
>  
> ```
The output with different values for `fileCount`:
>
> ```
>  The disk "MyDisk" contains 0 file(s).
>  The disk "MyDisk" contains 1 file(s).
>  The disk "MyDisk" contains 1,273 file(s).
>  
> ```


For more sophisticated patterns, you can use a `ChoiceFormat`
to produce correct forms for singular and plural:
>
> ```
>  MessageFormat form = new MessageFormat("The disk \"{1}\" contains {0}.");
>  double[] filelimits = {0,1,2};
>  String[] filepart = {"no files","one file","{0,number} files"};
>  ChoiceFormat fileform = new ChoiceFormat(filelimits, filepart);
>  form.setFormatByArgumentIndex(0, fileform);
>
>  int fileCount = 1273;
>  String diskName = "MyDisk";
>  Object[] testArgs = {new Long(fileCount), diskName};
>
>  System.out.println(form.format(testArgs));
>  
> ```
The output with different values for `fileCount`:
>
> ```
>  The disk "MyDisk" contains no files.
>  The disk "MyDisk" contains one file.
>  The disk "MyDisk" contains 1,273 files.
>  
> ```


You can create the `ChoiceFormat` programmatically, as in the
above example, or by using a pattern. See `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ChoiceFormat.html`
for more information.
>
>     form.applyPattern(
>         "There {0,choice,0#are no files|1#is one file|1<are {0,number,integer} files}.");
>      

**Note:** As we see above, the string produced
by a `ChoiceFormat` in `MessageFormat` is treated as special;
occurrences of '{' are used to indicate subformats, and cause recursion.
If you create both a `MessageFormat` and `ChoiceFormat`
programmatically (instead of using the string patterns), then be careful not to
produce a format that recurses on itself, which will cause an infinite loop.


When a single argument is parsed more than once in the string, the last match
will be the final result of the parsing. For example,
>
> ```
>  MessageFormat mf = new MessageFormat("{0,number,#.##}, {0,number,#.#}");
>  Object[] objs = {new Double(3.1415)};
>  String result = mf.format( objs );
>  // result now equals "3.14, 3.1"
>  objs = null;
>  objs = mf.parse(result, new ParsePosition(0));
>  // objs now equals {new Double(3.1)}
>  
> ```


Likewise, parsing with a `MessageFormat` object using patterns containing
multiple occurrences of the same argument would return the last match. For
example,
>
> ```
>  MessageFormat mf = new MessageFormat("{0}, {0}, {0}");
>  String forParsing = "x, y, z";
>  Object[] objs = mf.parse(forParsing, new ParsePosition(0));
>  // result now equals {new String("z")}
>  
> ```

#### Synchronization


Message 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 Also

- `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/NumberFormat.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DecimalFormat.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DecimalFormatSymbols.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ChoiceFormat.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/DateFormat.html`
- `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/SimpleDateFormat.html`

### Nested Class Summary

|---|---|---|---|
| class | [MessageFormat.Field](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.Field.html) || Defines constants that are used as attribute keys in the `AttributedCharacterIterator` returned from `MessageFormat.formatToCharacterIterator`. |

### Public Constructor Summary

|---|---|
|   | [MessageFormat](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#MessageFormat(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern) Constructs a MessageFormat for the default `https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.Category.html#FORMAT` locale and the specified pattern. |
|   | [MessageFormat](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#MessageFormat(java.lang.String,%20java.util.Locale))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, [Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html) locale) Constructs a MessageFormat for the specified locale and pattern. |

### Public Method Summary

|---|---|
| void | [applyPattern](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#applyPattern(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern) Sets the pattern used by this message format. |
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#clone())() Creates and returns a copy of this object. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Equality comparison between two message format objects |
| final [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) | [format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.Object[],%20java.lang.StringBuffer,%20java.text.FieldPosition))([Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments, [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) result, [FieldPosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/FieldPosition.html) pos) Formats an array of objects and appends the `MessageFormat`'s pattern, with format elements replaced by the formatted objects, to the provided `StringBuffer`. |
| final [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) | [format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.Object,%20java.lang.StringBuffer,%20java.text.FieldPosition))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments, [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) result, [FieldPosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/FieldPosition.html) pos) Formats an array of objects and appends the `MessageFormat`'s pattern, with format elements replaced by the formatted objects, to the provided `StringBuffer`. |
| static [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.String,%20java.lang.Object...))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, [Object...](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments) Creates a MessageFormat with the given pattern and uses it to format the given arguments. |
| [AttributedCharacterIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/AttributedCharacterIterator.html) | [formatToCharacterIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#formatToCharacterIterator(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments) Formats an array of objects and inserts them into the `MessageFormat`'s pattern, producing an `AttributedCharacterIterator`. |
| [Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) | [getFormats](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#getFormats())() Gets the formats used for the format elements in the previously set pattern string. |
| [Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) | [getFormatsByArgumentIndex](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#getFormatsByArgumentIndex())() Gets the formats used for the values passed into `format` methods or returned from `parse` methods. |
| [Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html) | [getLocale](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#getLocale())() Gets the locale that's used when creating or comparing subformats. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#hashCode())() Generates a hash code for the message format object. |
| [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [parse](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#parse(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source) Parses text from the beginning of the given string to produce an object array. |
| [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [parse](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#parse(java.lang.String,%20java.text.ParsePosition))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source, [ParsePosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParsePosition.html) pos) Parses the string. |
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [parseObject](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#parseObject(java.lang.String,%20java.text.ParsePosition))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source, [ParsePosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParsePosition.html) pos) Parses text from a string to produce an object array. |
| void | [setFormat](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormat(int,%20java.text.Format))(int formatElementIndex, [Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) newFormat) Sets the format to use for the format element with the given format element index within the previously set pattern string. |
| void | [setFormatByArgumentIndex](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormatByArgumentIndex(int,%20java.text.Format))(int argumentIndex, [Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) newFormat) Sets the format to use for the format elements within the previously set pattern string that use the given argument index. |
| void | [setFormats](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormats(java.text.Format[]))([Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) newFormats) Sets the formats to use for the format elements in the previously set pattern string. |
| void | [setFormatsByArgumentIndex](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormatsByArgumentIndex(java.text.Format[]))([Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) newFormats) Sets the formats to use for the values passed into `format` methods or returned from `parse` methods. |
| void | [setLocale](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setLocale(java.util.Locale))([Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html) locale) Sets the locale to be used when creating or comparing subformats. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toPattern](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#toPattern())() Returns a pattern representing the current state of the message format. |

### Inherited Method Summary

From class [java.text.Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#clone())() Creates and returns a copy of this object. |
| final [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#format(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Formats an object to produce a string. |
| abstract [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) | [format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#format(java.lang.Object,%20java.lang.StringBuffer,%20java.text.FieldPosition))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj, [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) toAppendTo, [FieldPosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/FieldPosition.html) pos) Formats an object and appends the resulting text to a given string buffer. |
| [AttributedCharacterIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/AttributedCharacterIterator.html) | [formatToCharacterIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#formatToCharacterIterator(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Formats an Object producing an `AttributedCharacterIterator`. |
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [parseObject](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#parseObject(java.lang.String))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source) Parses text from the beginning of the given string to produce an object. |
| abstract [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [parseObject](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html#parseObject(java.lang.String,%20java.text.ParsePosition))([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source, [ParsePosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParsePosition.html) pos) Parses text from a string to produce an object. |

From class [java.lang.Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)

|---|---|
| [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) | [clone](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#clone())() Creates and returns a copy of this `Object`. |
| boolean | [equals](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#equals(java.lang.Object))([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj) Compares this instance with the specified object and indicates if they are equal. |
| void | [finalize](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#finalize())() Invoked when the garbage collector has detected that this instance is no longer reachable. |
| final [Class](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html)\<?\> | [getClass](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#getClass())() Returns the unique instance of `https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Class.html` that represents this object's class. |
| int | [hashCode](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#hashCode())() Returns an integer hash code for this object. |
| final void | [notify](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notify())() Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| final void | [notifyAll](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#notifyAll())() Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up. |
| [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) | [toString](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#toString())() Returns a string containing a concise, human-readable description of this object. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long,%20int))(long timeout, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait(long))(long timeout) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires. |
| final void | [wait](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html#wait())() Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object. |

## Public Constructors

#### public
**MessageFormat**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern)

Constructs a MessageFormat for the default
`https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.Category.html#FORMAT` 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat#patterns).

##### Parameters

| pattern | the pattern for this message format |
|---|---|

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if the pattern is invalid |
|---|---|

#### public
**MessageFormat**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, [Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html) 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat#patterns).

##### Parameters

| pattern | the pattern for this message format |
| locale | the locale for this message format |
|---|---|

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if the pattern is invalid |
|---|---|

## Public Methods

#### public void
**applyPattern**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat#patterns).

##### Parameters

| pattern | the pattern for this message format |
|---|---|

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if the pattern is invalid |
|---|---|

#### public [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)
**clone**
()

Creates and returns a copy of this object.

##### Returns

- a clone of this instance.

#### public boolean
**equals**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) obj)

Equality comparison between two message format objects

##### Parameters

| obj | the object to compare this instance with. |
|---|---|

##### Returns

- `true` if the specified object is equal to this `Object`; `false` otherwise.

#### public final [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html)
**format**
([Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments, [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) result, [FieldPosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/FieldPosition.html) 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()` |


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. |
|---|---|

##### Returns

- the string buffer passed in as `result`, with formatted text appended

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if an argument in the `arguments` array is not of the type expected by the format element(s) that use it. |
|---|---|

#### public final [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html)
**format**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments, [StringBuffer](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/StringBuffer.html) result, [FieldPosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/FieldPosition.html) 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
> `` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.Object[],%20java.lang.StringBuffer,%20java.text.FieldPosition)`((Object[]) arguments, result, pos) ``

<br />

##### 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if an argument in the `arguments` array is not of the type expected by the format element(s) that use it. |
|---|---|

#### public static [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html)
**format**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) pattern, [Object...](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) arguments)

Creates a MessageFormat with the given pattern and uses it
to format the given arguments. This is equivalent to
> ``(new `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#MessageFormat(java.lang.String)`(pattern)).`https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.Object[],%20java.lang.StringBuffer,%20java.text.FieldPosition)`(arguments, new StringBuffer(), null).toString()``

<br />

##### Parameters

| pattern | the pattern string |
| arguments | object(s) to format |
|---|---|

##### Returns

- the formatted string

##### Throws

| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | 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. |
|---|---|

#### public [AttributedCharacterIterator](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/AttributedCharacterIterator.html)
**formatToCharacterIterator**
([Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html) 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
> `` `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#format(java.lang.Object[],%20java.lang.StringBuffer,%20java.text.FieldPosition)`(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.

##### Parameters

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

##### Returns

- AttributedCharacterIterator describing the formatted value.

##### Throws

| [NullPointerException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `arguments` is null. |
| [IllegalArgumentException](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/IllegalArgumentException.html) | if an argument in the `arguments` array is not of the type expected by the format element(s) that use it. |
|---|---|

#### public [Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html)
**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
`https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#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

#### public [Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html)
**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

#### public [Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html)
**getLocale**
()

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

##### Returns

- the locale used when creating or comparing subformats

#### public int
**hashCode**
()

Generates a hash code for the message format object.

##### Returns

- this object's hash code.

#### public [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)
**parse**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source)

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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#parse(java.lang.String,%20java.text.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](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParseException.html) | if the beginning of the specified string cannot be parsed. |
|---|---|

#### public [Object\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)
**parse**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source, [ParsePosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParsePosition.html) 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.

<br />

##### Parameters

| source | the string to parse |
| pos | the parse position |
|---|---|

##### Returns

- an array of parsed objects

#### public [Object](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/Object.html)
**parseObject**
([String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html) source, [ParsePosition](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/ParsePosition.html) 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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#parse(java.lang.String,%20java.text.ParsePosition)` method for more information
on message parsing.

##### 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `pos` is null. |
|---|---|

#### public void
**setFormat**
(int formatElementIndex, [Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) 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
`https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormatByArgumentIndex(int,%20java.text.Format)`
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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/ArrayIndexOutOfBoundsException.html) | if `formatElementIndex` is equal to or larger than the number of format elements in the pattern string |
|---|---|

#### public void
**setFormatByArgumentIndex**
(int argumentIndex, [Format](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) 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 |
|---|---|

#### public void
**setFormats**
([Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) 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
`https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#setFormatsByArgumentIndex(java.text.Format[])`
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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `newFormats` is null |
|---|---|

#### public void
**setFormatsByArgumentIndex**
([Format\[\]](https://developers.google.com/j2objc/javadoc/jre/reference/java/text/Format.html) 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](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/NullPointerException.html) | if `newFormats` is null |
|---|---|

#### public void
**setLocale**
([Locale](https://developers.google.com/j2objc/javadoc/jre/reference/java/util/Locale.html) locale)

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

- to the `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#applyPattern(java.lang.String)` and `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#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 `https://developers.google.com/j2objc/javadoc/jre/reference/java/text/MessageFormat.html#formatToCharacterIterator(java.lang.Object)` 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.

<br />

##### Parameters

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

#### public [String](https://developers.google.com/j2objc/javadoc/jre/reference/java/lang/String.html)
**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