MessageFormat (ICU4J 76)

java.lang.Object
- java.text.Format
- - com.ibm.icu.text.UFormat
  - - com.ibm.icu.text.MessageFormat

All Implemented Interfaces:: Serializable, Cloneable

public class MessageFormat
extends UFormat

[icu enhancement] ICU's replacement for java.text.MessageFormat. Methods, fields, and other functionality specific to ICU are labeled '[icu]'.

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.

A MessageFormat is constructed from a pattern string with arguments in {curly braces} which will be replaced by formatted values.

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). 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 and the subformats used for inserted arguments.

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 usesNamedArguments()).

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.

An argument might specify a "simple" type for which the specified Format object is created, cached and used.

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.

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.

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 a Map (which works for both named and numbered arguments).

Each argument is matched with one of the input values by array index or map key and formatted according to its pattern specification (or using a custom Format object if one was set). A numbered pattern argument is matched with a map key that contains that number as an ASCII-decimal-digit string (without leading zero).

Patterns and Their Interpretation

MessageFormat uses patterns of the following form:

 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 ChoiceFormat
 pluralStyle: see PluralFormat
 selectStyle: see 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 | "::" argSkeletonText

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 apostrophe inside or outside of a quoted string represents one literal apostrophe.
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.
See also MessagePattern.ApostropheMode
In argStyleText, every single ASCII apostrophe begins and ends quoted literal text, and unquoted {curly braces} must occur in matched pairs.

Recommendation: Use the real apostrophe (single quote) character \\u2019 for human-readable text, and use the ASCII apostrophe (\\u0027 ' ) only in program syntax, like quoting in MessageFormat. See the annotations for U+0027 Apostrophe in The Unicode Standard.

The choice argument type is deprecated. Use plural arguments for proper plural selection, and select arguments for simple selection among a fixed set of choices.

The argType and argStyle 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. Any argStyleText must be a valid pattern string for the Format subclass used.

argType	argStyle	resulting Format object
(none)		`null`
`number`	(none)	`NumberFormat.getInstance(getLocale())`
	`integer`	`NumberFormat.getIntegerInstance(getLocale())`
	`currency`	`NumberFormat.getCurrencyInstance(getLocale())`
	`percent`	`NumberFormat.getPercentInstance(getLocale())`
	argStyleText	`new DecimalFormat(argStyleText, new DecimalFormatSymbols(getLocale()))`
	argSkeletonText	`NumberFormatter.forSkeleton(argSkeletonText).locale(getLocale()).toFormat()`
`date`	(none)	`DateFormat.getDateInstance(DateFormat.DEFAULT, getLocale())`
	`short`	`DateFormat.getDateInstance(DateFormat.SHORT, getLocale())`
	`medium`	`DateFormat.getDateInstance(DateFormat.DEFAULT, getLocale())`
	`long`	`DateFormat.getDateInstance(DateFormat.LONG, getLocale())`
	`full`	`DateFormat.getDateInstance(DateFormat.FULL, getLocale())`
	argStyleText	`new SimpleDateFormat(argStyleText, getLocale())`
	argSkeletonText	`DateFormat.getInstanceForSkeleton(argSkeletonText, getLocale())`
`time`	(none)	`DateFormat.getTimeInstance(DateFormat.DEFAULT, getLocale())`
	`short`	`DateFormat.getTimeInstance(DateFormat.SHORT, getLocale())`
	`medium`	`DateFormat.getTimeInstance(DateFormat.DEFAULT, getLocale())`
	`long`	`DateFormat.getTimeInstance(DateFormat.LONG, getLocale())`
	`full`	`DateFormat.getTimeInstance(DateFormat.FULL, getLocale())`
	argStyleText	`new SimpleDateFormat(argStyleText, getLocale())`
`spellout`	argStyleText (optional)	`new RuleBasedNumberFormat(getLocale(), RuleBasedNumberFormat.SPELLOUT) .setDefaultRuleset(argStyleText);`
`ordinal`	argStyleText (optional)	`new RuleBasedNumberFormat(getLocale(), RuleBasedNumberFormat.ORDINAL) .setDefaultRuleset(argStyleText);`
`duration`	argStyleText (optional)	`new RuleBasedNumberFormat(getLocale(), RuleBasedNumberFormat.DURATION) .setDefaultRuleset(argStyleText);`

Differences from java.text.MessageFormat

The ICU MessageFormat supports both named and numbered arguments, while the JDK MessageFormat only supports numbered arguments. Named arguments make patterns more readable.

ICU implements a more user-friendly apostrophe quoting syntax. In message text, an apostrophe only begins quoting literal text if it immediately precedes a syntax character (mostly {curly braces}).
In the JDK MessageFormat, an apostrophe always begins quoting, which requires common text like "don't" and "aujourd'hui" to be written with doubled apostrophes like "don''t" and "aujourd''hui". For more details see MessagePattern.ApostropheMode.

ICU does not create a ChoiceFormat object for a choiceArg, pluralArg or selectArg but rather handles such arguments itself. The JDK MessageFormat does create and use a ChoiceFormat object (new ChoiceFormat(argStyleText)). The JDK does not support plural and select arguments at all.

Both the ICU and the JDK MessageFormat can control the argument formats by using argStyle. But the JDK MessageFormat only supports predefined formats and number / date / time pattern strings (which would need to be localized).
ICU supports everything the JDK does, and also number / date / time skeletons using the :: prefix (which automatically yield output appropriate for the MessageFormat locale).

Argument formatting

Arguments are formatted according to their type, using the default ICU formatters for those types, unless otherwise specified. For unknown types, MessageFormat will call toString().

There are also several ways to control the formatting.

We recommend you use default styles, predefined style values, skeletons, or preformatted values, but not pattern strings or custom format objects.

For more details, see the ICU User Guide.

Usage Information

Here are some examples of usage:

 Object[] arguments = {
     7,
     new Date(System.currentTimeMillis()),
     "a disturbance in the Force"
 };

 String result = MessageFormat.format(
     "At {1,time,::jmm} on {1,date,::dMMMM}, there was {2} on planet {0,number,integer}.",
     arguments);

 output: At 4:34 PM on March 23, there was a disturbance
           in the Force on planet 7.

Typically, the message format will come from resources, and the arguments will be dynamically set at runtime.

Example 2:

 Object[] testArgs = { 3, "MyDisk" };

 MessageFormat form = new MessageFormat(
     "The disk \"{1}\" contains {0} file(s).");

 System.out.println(form.format(testArgs));

 // output, with different testArgs
 output: The disk "MyDisk" contains 0 file(s).
 output: The disk "MyDisk" contains 1 file(s).
 output: The disk "MyDisk" contains 1,273 file(s).

For messages that include plural forms, you can use a plural argument:

 MessageFormat msgFmt = new MessageFormat(
     "{num_files, plural, " +
     "=0{There are no files on disk \"{disk_name}\".}" +
     "=1{There is one file on disk \"{disk_name}\".}" +
     "other{There are # files on disk \"{disk_name}\".}}",
     ULocale.ENGLISH);
 Map args = new HashMap();
 args.put("num_files", 0);
 args.put("disk_name", "MyDisk");
 System.out.println(msgFmt.format(args));
 args.put("num_files", 3);
 System.out.println(msgFmt.format(args));

 output:
 There are no files on disk "MyDisk".
 There are 3 files on "MyDisk".

See PluralFormat and PluralRules for details.

Synchronization

MessageFormats 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.

Author:: Mark Davis, Markus Scherer
See Also:: Locale, Format, NumberFormat, DecimalFormat, ChoiceFormat, PluralFormat, SelectFormat, Serialized Form
Status:: Stable ICU 3.0.

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`MessageFormat.Field` Defines constants that are used as attribute keys in the `AttributedCharacterIterator` returned from `MessageFormat.formatToCharacterIterator`.

Nested classes/interfaces inherited from class com.ibm.icu.text.UFormat
UFormat.SpanField

Constructor Summary

Constructors
Constructor and Description
`MessageFormat(String pattern)` Constructs a MessageFormat for the default `FORMAT` locale and the specified pattern.
`MessageFormat(String pattern, Locale locale)` Constructs a MessageFormat for the specified locale and pattern.
`MessageFormat(String pattern, ULocale locale)` Constructs a MessageFormat for the specified locale and pattern.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`applyPattern(String pttrn)` Sets the pattern used by this message format.
`void`	`applyPattern(String pattern, MessagePattern.ApostropheMode aposMode)` [icu] Sets the ApostropheMode and the pattern used by this message format.
`static String`	`autoQuoteApostrophe(String pattern)` [icu] Converts an 'apostrophe-friendly' pattern into a standard pattern.
`Object`	`clone()`
`boolean`	`equals(Object obj)`
`StringBuffer`	`format(Map<String,Object> arguments, StringBuffer result, FieldPosition pos)` Formats a map of objects and appends the `MessageFormat`'s pattern, with arguments replaced by the formatted objects, to the provided `StringBuffer`.
`StringBuffer`	`format(Object[] arguments, StringBuffer result, FieldPosition pos)` Formats an array of objects and appends the `MessageFormat`'s pattern, with arguments replaced by the formatted objects, to the provided `StringBuffer`.
`StringBuffer`	`format(Object arguments, StringBuffer result, FieldPosition pos)` Formats a map or array of objects and appends the `MessageFormat`'s pattern, with format elements replaced by the formatted objects, to the provided `StringBuffer`.
`static String`	`format(String pattern, Map<String,Object> arguments)` Creates a MessageFormat with the given pattern and uses it to format the given arguments.
`static String`	`format(String pattern, Object... arguments)` Creates a MessageFormat with the given pattern and uses it to format the given arguments.
`AttributedCharacterIterator`	`formatToCharacterIterator(Object arguments)` Formats an array of objects and inserts them into the `MessageFormat`'s pattern, producing an `AttributedCharacterIterator`.
`MessagePattern.ApostropheMode`	`getApostropheMode()` [icu]
`Set<String>`	`getArgumentNames()` [icu] Returns the top-level argument names.
`Format`	`getFormatByArgumentName(String argumentName)` [icu] Returns the first top-level format associated with the given argument name.
`Format[]`	`getFormats()` Returns the Format objects used for the format elements in the previously set pattern string.
`Format[]`	`getFormatsByArgumentIndex()` Returns the Format objects used for the values passed into `format` methods or returned from `parse` methods.
`Locale`	`getLocale()` Returns the locale that's used when creating or comparing subformats.
`ULocale`	`getULocale()` [icu] Returns the locale that's used when creating argument Format objects.
`int`	`hashCode()`
`Object[]`	`parse(String source)` Parses text from the beginning of the given string to produce an object array.
`Object[]`	`parse(String source, ParsePosition pos)` Parses the string.
`Object`	`parseObject(String source, ParsePosition pos)` Parses text from a string to produce an object array or Map.
`Map<String,Object>`	`parseToMap(String source)` [icu] Parses text from the beginning of the given string to produce a map from argument to values.
`Map<String,Object>`	`parseToMap(String source, ParsePosition pos)` [icu] Parses the string, returning the results in a Map.
`void`	`setFormat(int formatElementIndex, Format newFormat)` Sets the Format object to use for the format element with the given format element index within the previously set pattern string.
`void`	`setFormatByArgumentIndex(int argumentIndex, Format newFormat)` Sets the Format object to use for the format elements within the previously set pattern string that use the given argument index.
`void`	`setFormatByArgumentName(String argumentName, Format newFormat)` [icu] Sets the Format object to use for the format elements within the previously set pattern string that use the given argument name.
`void`	`setFormats(Format[] newFormats)` Sets the Format objects to use for the format elements in the previously set pattern string.
`void`	`setFormatsByArgumentIndex(Format[] newFormats)` Sets the Format objects to use for the values passed into `format` methods or returned from `parse` methods.
`void`	`setFormatsByArgumentName(Map<String,Format> newFormats)` [icu] Sets the Format objects to use for the values passed into `format` methods or returned from `parse` methods.
`void`	`setLocale(Locale locale)` Sets the locale to be used for creating argument Format objects.
`void`	`setLocale(ULocale locale)` Sets the locale to be used for creating argument Format objects.
`String`	`toPattern()` Returns the applied pattern string.
`boolean`	`usesNamedArguments()` [icu] Returns true if this MessageFormat uses named arguments, and false otherwise.

Methods inherited from class com.ibm.icu.text.UFormat
getLocale

Methods inherited from class java.text.Format
format, parseObject

Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- MessageFormat
```
public MessageFormat(String pattern)
```
  Constructs a MessageFormat for the default FORMAT locale and the specified pattern. Sets the locale and calls applyPattern(pattern).
  
  Parameters:
  
  pattern - the pattern for this message format
  
  Throws:
  
  IllegalArgumentException - if the pattern is invalid
  
  See Also:
  
  ULocale.Category.FORMAT
  
  Status:
  Stable ICU 3.0.
- MessageFormat
```
public MessageFormat(String pattern,
                     Locale locale)
```
  Constructs a MessageFormat for the specified locale and pattern. Sets the locale and calls applyPattern(pattern).
  
  Parameters:
  
  pattern - the pattern for this message format
  
  locale - the locale for this message format
  
  Throws:
  
  IllegalArgumentException - if the pattern is invalid
  
  Status:
  Stable ICU 3.0.
- MessageFormat
```
public MessageFormat(String pattern,
                     ULocale locale)
```
  Constructs a MessageFormat for the specified locale and pattern. Sets the locale and calls applyPattern(pattern).
  
  Parameters:
  
  pattern - the pattern for this message format
  
  locale - the locale for this message format
  
  Throws:
  
  IllegalArgumentException - if the pattern is invalid
  
  Status:
  Stable ICU 3.2.

Method Detail

setLocale
```
public void setLocale(Locale locale)
```
Sets the locale to be used for creating argument Format objects. This affects subsequent calls to the applyPattern method as well as to the format and formatToCharacterIterator methods.

Parameters:

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

Status:
Stable ICU 3.0.

setLocale
```
public void setLocale(ULocale locale)
```
Sets the locale to be used for creating argument Format objects. This affects subsequent calls to the applyPattern method as well as to the format and formatToCharacterIterator methods.

Parameters:

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

Status:
Stable ICU 3.2.

getLocale
```
public Locale getLocale()
```
Returns the locale that's used when creating or comparing subformats.

Returns:

the locale used when creating or comparing subformats

Status:
Stable ICU 3.0.

getULocale
```
public ULocale getULocale()
```
[icu] Returns the locale that's used when creating argument Format objects.

Returns:

the locale used when creating or comparing subformats

Status:
Stable ICU 3.2.

applyPattern
```
public void applyPattern(String pttrn)
```
Sets the pattern used by this message format. Parses the pattern and caches Format objects for simple argument types. Patterns and their interpretation are specified in the class description.

Parameters:

pttrn - the pattern for this message format

Throws:

IllegalArgumentException - if the pattern is invalid

Status:
Stable ICU 3.0.

applyPattern
```
public void applyPattern(String pattern,
                         MessagePattern.ApostropheMode aposMode)
```
[icu] Sets the ApostropheMode and the pattern used by this message format. Parses the pattern and caches Format objects for simple argument types. Patterns and their interpretation are specified in the class description.
This method is best used only once on a given object to avoid confusion about the mode, and after constructing the object with an empty pattern string to minimize overhead.

Parameters:

pattern - the pattern for this message format

aposMode - the new ApostropheMode

Throws:

IllegalArgumentException - if the pattern is invalid

See Also:

MessagePattern.ApostropheMode

Status:
Stable ICU 4.8.

getApostropheMode
```
public MessagePattern.ApostropheMode getApostropheMode()
```
[icu]

Returns:

this instance's ApostropheMode.

Status:
Stable ICU 4.8.

toPattern
```
public String toPattern()
```
Returns the applied pattern string.

Returns:

the pattern string

Throws:

IllegalStateException - after custom Format objects have been set via setFormat() or similar APIs

Status:
Stable ICU 3.0.

setFormatsByArgumentIndex
```
public void setFormatsByArgumentIndex(Format[] newFormats)
```
Sets the Format objects 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. This method is only supported if the format does not use named arguments, otherwise an IllegalArgumentException is thrown.

Parameters:

newFormats - the new formats to use

Throws:

NullPointerException - if newFormats is null

IllegalArgumentException - if this formatter uses named arguments

Status:
Stable ICU 3.0.

setFormatsByArgumentName
```
public void setFormatsByArgumentName(Map<String,Format> newFormats)
```
[icu] Sets the Format objects to use for the values passed into format methods or returned from parse methods. The keys in newFormats are the argument names in the previously set pattern string, and the values are the formats.
Only argument names from the pattern string are considered. Extra keys in newFormats that do not correspond to an argument name are ignored. Similarly, if there is no format in newFormats for an argument name, the formatter for that argument remains unchanged.
This may be called on formats that do not use named arguments. In this case the map will be queried for key Strings that represent argument indices, e.g. "0", "1", "2" etc.

Parameters:

newFormats - a map from String to Format providing new formats for named arguments.

Status:
Stable ICU 3.8.

setFormats
```
public void setFormats(Format[] newFormats)
```
Sets the Format objects 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

Status:
Stable ICU 3.0.

setFormatByArgumentIndex
```
public void setFormatByArgumentIndex(int argumentIndex,
                                     Format newFormat)
```
Sets the Format object 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. This method is only supported when exclusively numbers are used for argument names. Otherwise an IllegalArgumentException is thrown.

Parameters:

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

newFormat - the new format to use

Throws:

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

setFormatByArgumentName
```
public void setFormatByArgumentName(String argumentName,
                                    Format newFormat)
```
[icu] Sets the Format object to use for the format elements within the previously set pattern string that use the given argument name.
If the argument name 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 name is not used for any format element in the pattern string, then the new format is ignored.
This API may be used on formats that do not use named arguments. In this case argumentName should be a String that names an argument index, e.g. "0", "1", "2"... etc. If it does not name a valid index, the format will be ignored. No error is thrown.

Parameters:

argumentName - the name of the argument to change

newFormat - the new format to use

Status:
Stable ICU 3.8.

setFormat
```
public void setFormat(int formatElementIndex,
                      Format newFormat)
```
Sets the Format object 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

Status:
Stable ICU 3.0.

getFormatsByArgumentIndex
```
public Format[] getFormatsByArgumentIndex()
```
Returns the Format objects 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. This method is only supported when exclusively numbers are used for argument names. Otherwise an IllegalArgumentException is thrown.

Returns:

the formats used for the arguments within the pattern

Throws:

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

getFormats
```
public Format[] getFormats()
```
Returns the Format objects 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. This method is only supported when exclusively numbers are used for argument names. Otherwise an IllegalArgumentException is thrown.

Returns:

the formats used for the format elements in the pattern

Throws:

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

getArgumentNames
```
public Set<String> getArgumentNames()
```
[icu] Returns the top-level argument names. For more details, see setFormatByArgumentName(String, Format).

Returns:

a Set of argument names

Status:
Stable ICU 4.8.

getFormatByArgumentName
```
public Format getFormatByArgumentName(String argumentName)
```
[icu] Returns the first top-level format associated with the given argument name. For more details, see setFormatByArgumentName(String, Format).

Parameters:

argumentName - The name of the desired argument.

Returns:

the Format associated with the name, or null if there isn't one.

Status:
Stable ICU 4.8.

format

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

Formats an array of objects and appends the MessageFormat's pattern, with arguments 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. When an argument is unavailable no substitution is performed.

argType or Format	value object	Formatted Text
any	unavailable	`"{" + argNameOrNumber + "}"`
any	`null`	`"null"`
custom Format `!= null`	any	`customFormat.format(argument)`
noneArg, or custom Format `== null`	`instanceof Number`	`NumberFormat.getInstance(getLocale()).format(argument)`
noneArg, or custom Format `== null`	`instanceof Date`	`DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT, getLocale()).format(argument)`
noneArg, or custom Format `== null`	`instanceof String`	`argument`
noneArg, or custom Format `== null`	any	`argument.toString()`
complexArg	any	result of recursive formatting of a selected sub-message

If pos is non-null, and refers to Field.ARGUMENT, the location of the first formatted string will be returned. This method is only supported when the format does not use named arguments, otherwise an IllegalArgumentException is thrown.

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 a value in the arguments array is not of the type expected by the corresponding argument or custom Format object.; IllegalArgumentException - if this format uses named arguments
Status:: Stable ICU 3.0.

format
```
public final StringBuffer format(Map<String,Object> arguments,
                                 StringBuffer result,
                                 FieldPosition pos)
```
Formats a map of objects and appends the MessageFormat's pattern, with arguments 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 value corresponding to the format element's argument name.
A numbered pattern argument is matched with a map key that contains that number as an ASCII-decimal-digit string (without leading zero).
An argument is unavailable if arguments is null or does not have a value corresponding to an argument name in the pattern. When an argument is unavailable no substitution is performed.

Parameters:

arguments - a map 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 passed-in StringBuffer

Throws:

IllegalArgumentException - if a value in the arguments array is not of the type expected by the corresponding argument or custom Format object.

Status:
Stable ICU 3.8.

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

IllegalArgumentException - if a value in the arguments array is not of the type expected by the corresponding argument or custom Format object.

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

format
```
public static String format(String pattern,
                            Map<String,Object> arguments)
```
Creates a MessageFormat with the given pattern and uses it to format the given arguments. The pattern must identifyarguments by name instead of by number.

Throws:

IllegalArgumentException - if the pattern is invalid

IllegalArgumentException - if a value in the arguments array is not of the type expected by the corresponding argument or custom Format object.

See Also:

format(Map, StringBuffer, FieldPosition), format(String, Object[])

Status:
Stable ICU 3.8.

usesNamedArguments
```
public boolean usesNamedArguments()
```
[icu] Returns true if this MessageFormat uses named arguments, and false otherwise. See class description.

Returns:

true if named arguments are used.

Status:
Stable ICU 3.8.

format
```
public final StringBuffer format(Object arguments,
                                 StringBuffer result,
                                 FieldPosition pos)
```
Formats a map or 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 either of
format((Object[]) arguments, result, pos) format((Map) arguments, result, pos)
A map must be provided if this format uses named arguments, otherwise an IllegalArgumentException will be thrown.

Specified by:

format in class Format

Parameters:

arguments - a map or array of objects to be formatted

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 arguments is not of the type expected by the format element(s) that use it

IllegalArgumentException - if arguments is an array of Object and this format uses named arguments

Status:
Stable ICU 3.0.

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 a value in the arguments array is not of the type expected by the corresponding argument or custom Format object.

Status:
Stable ICU 3.8.

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 did 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.
Throws:

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

parseToMap
```
public Map<String,Object> parseToMap(String source,
                                     ParsePosition pos)
```
[icu] Parses the string, returning the results in a Map. This is similar to the version that returns an array of Object. This supports both named and numbered arguments-- if numbered, the keys in the map are the corresponding ASCII-decimal-digit strings (e.g. "0", "1", "2"...).

Parameters:

source - the text to parse

pos - the position at which to start parsing. on return, contains the result of the parse.

Returns:

a Map containing key/value pairs for each parsed argument.

Status:
Stable ICU 3.8.

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.

IllegalArgumentException - if this format uses named arguments

Status:
Stable ICU 3.0.

parseToMap
```
public Map<String,Object> parseToMap(String source)
                              throws ParseException
```
[icu] Parses text from the beginning of the given string to produce a map from argument to values. 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:

A Map parsed from the string.

Throws:

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

See Also:

parseToMap(String, ParsePosition)

Status:
Stable ICU 3.8.

parseObject
```
public Object parseObject(String source,
                          ParsePosition pos)
```
Parses text from a string to produce an object array or Map.
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 parsed from the string, either an array of Object, or a Map, depending on whether named arguments are used. This can be queried using usesNamedArguments. In case of error, returns null.

Throws:

NullPointerException - if pos is null.

Status:
Stable ICU 3.0.

clone
```
public Object clone()
```
Overrides:

clone in class Format

Status:
Stable ICU 3.0.

equals
```
public boolean equals(Object obj)
```
Overrides:

equals in class Object

Status:
Stable ICU 3.0.

hashCode
```
public int hashCode()
```
Overrides:

hashCode in class Object

Status:
Stable ICU 3.0.

autoQuoteApostrophe
```
public static String autoQuoteApostrophe(String pattern)
```
[icu] Converts an 'apostrophe-friendly' pattern into a standard pattern. This is obsolete for ICU 4.8 and higher MessageFormat pattern strings. It can still be useful together with MessageFormat.
See the class description for more about apostrophes and quoting, and differences between ICU and MessageFormat.
MessageFormat and ICU 4.6 and earlier MessageFormat treat all ASCII apostrophes as quotes, which is problematic in some languages, e.g. French, where apostrophe is commonly used. This utility assumes that only an unpaired apostrophe immediately before a brace is a true quote. Other unpaired apostrophes are paired, and the resulting standard pattern string is returned.
Note: It is not guaranteed that the returned pattern is indeed a valid pattern. The only effect is to convert between patterns having different quoting semantics.
Note: This method only works on top-level messageText, not messageText nested inside a complexArg.

Parameters:

pattern - the 'apostrophe-friendly' pattern to convert

Returns:

the standard equivalent of the original pattern

Status:
Stable ICU 3.4.

Class MessageFormat

Patterns and Their Interpretation

Differences from java.text.MessageFormat

Argument formatting

Usage Information

Synchronization

Nested Class Summary

Nested classes/interfaces inherited from class com.ibm.icu.text.UFormat

Constructor Summary

Method Summary

Methods inherited from class com.ibm.icu.text.UFormat

Methods inherited from class java.text.Format

Methods inherited from class java.lang.Object

Constructor Detail

MessageFormat

MessageFormat

MessageFormat

Method Detail

setLocale

setLocale

getLocale

getULocale

applyPattern

applyPattern

getApostropheMode

toPattern

setFormatsByArgumentIndex

setFormatsByArgumentName

setFormats

setFormatByArgumentIndex

setFormatByArgumentName

setFormat

getFormatsByArgumentIndex

getFormats

getArgumentNames

getFormatByArgumentName

format

format

format

format

usesNamedArguments

format

formatToCharacterIterator

parse

parseToMap

parse

parseToMap

parseObject

clone

equals

hashCode

autoQuoteApostrophe