Class SelectFormat
- All Implemented Interfaces:
Serializable
,Cloneable
SelectFormat
supports the creation of internationalized
messages by selecting phrases based on keywords. The pattern specifies
how to map keywords to phrases and provides a default phrase. The
object provided to the format method is a string that's matched
against the keywords. If there is a match, the corresponding phrase
is selected; otherwise, the default phrase is used.
Using SelectFormat
for Gender Agreement
Note: Typically, select formatting is done via MessageFormat
with a select
argument type,
rather than using a stand-alone SelectFormat
.
The main use case for the select format is gender based inflection. When names or nouns are inserted into sentences, their gender can affect pronouns, verb forms, articles, and adjectives. Special care needs to be taken for the case where the gender cannot be determined. The impact varies between languages:
- English has three genders, and unknown gender is handled as a special case. Names use the gender of the named person (if known), nouns referring to people use natural gender, and inanimate objects are usually neutral. The gender only affects pronouns: "he", "she", "it", "they".
- German differs from English in that the gender of nouns is rather arbitrary, even for nouns referring to people ("Mädchen", girl, is neutral). The gender affects pronouns ("er", "sie", "es"), articles ("der", "die", "das"), and adjective forms ("guter Mann", "gute Frau", "gutes Mädchen").
- French has only two genders; as in German the gender of nouns is rather arbitrary - for sun and moon, the genders are the opposite of those in German. The gender affects pronouns ("il", "elle"), articles ("le", "la"), adjective forms ("bon", "bonne"), and sometimes verb forms ("allé", "allée").
- Polish distinguishes five genders (or noun classes), human masculine, animate non-human masculine, inanimate masculine, feminine, and neuter.
Some other languages have noun classes that are not related to gender, but similar in grammatical use. Some African languages have around 20 noun classes.
Note:For the gender of a person in a given sentence, we usually need to distinguish only between female, male and other/unknown.
To enable localizers to create sentence patterns that take their
language's gender dependencies into consideration, software has to provide
information about the gender associated with a noun or name to
MessageFormat
.
Two main cases can be distinguished:
- For people, natural gender information should be maintained for each person. Keywords like "male", "female", "mixed" (for groups of people) and "unknown" could be used.
- For nouns, grammatical gender information should be maintained for each noun and per language, e.g., in resource bundles. The keywords "masculine", "feminine", and "neuter" are commonly used, but some languages may require other keywords.
The resulting keyword is provided to MessageFormat
as a
parameter separate from the name or noun it's associated with. For example,
to generate a message such as "Jean went to Paris", three separate arguments
would be provided: The name of the person as argument 0, the gender of
the person as argument 1, and the name of the city as argument 2.
The sentence pattern for English, where the gender of the person has
no impact on this simple sentence, would not refer to argument 1 at all:
{0} went to {2}.
Note: The entire sentence should be included (and partially repeated) inside each phrase. Otherwise translators would have to be trained on how to move bits of the sentence in and out of the select argument of a message. (The examples below do not follow this recommendation!)
The sentence pattern for French, where the gender of the person affects the form of the participle, uses a select format based on argument 1:
{0} est {1, select, female {allée} other {allé}} à {2}.
Patterns can be nested, so that it's possible to handle interactions of number and gender where necessary. For example, if the above sentence should allow for the names of several people to be inserted, the following sentence pattern can be used (with argument 0 the list of people's names, argument 1 the number of people, argument 2 their combined gender, and argument 3 the city name):
{0} {1, plural, one {est {2, select, female {allée} other {allé}}} other {sont {2, select, female {allées} other {allés}}} }à {3}.
Patterns and Their Interpretation
The SelectFormat
pattern string defines the phrase output
for each user-defined keyword.
The pattern is a sequence of (keyword, message) pairs.
A keyword is a "pattern identifier": [^[[:Pattern_Syntax:][:Pattern_White_Space:]]]+
Each message is a MessageFormat pattern string enclosed in {curly braces}.
You always have to define a phrase for the default keyword
other
; this phrase is returned when the keyword
provided to
the format
method matches no other keyword.
If a pattern does not provide a phrase for other
, the method
it's provided to returns the error U_DEFAULT_KEYWORD_MISSING
.
Pattern_White_Space between keywords and messages is ignored.
Pattern_White_Space within a message is preserved and output.
Example: MessageFormat msgFmt = new MessageFormat("{0} est " + "{1, select, female {allée} other {allé}} à Paris.", new ULocale("fr")); Object args[] = {"Kirti","female"}; System.out.println(msgFmt.format(args));
Produces the output:
Kirti est allée à Paris.
- See Also:
-
Nested Class Summary
Nested classes/interfaces inherited from class java.text.Format
Format.Field
-
Constructor Summary
ConstructorsConstructorDescriptionSelectFormat
(String pattern) Creates a newSelectFormat
for a given pattern string. -
Method Summary
Modifier and TypeMethodDescriptionvoid
applyPattern
(String pattern) Sets the pattern used by this select format.boolean
format
(Object keyword, StringBuffer toAppendTo, FieldPosition pos) Selects the phrase for the given keyword.final String
Selects the phrase for the given keyword.int
hashCode()
parseObject
(String source, ParsePosition pos) This method is not supported bySelectFormat
.Returns the pattern for thisSelectFormat
toString()
Methods inherited from class java.text.Format
clone, format, formatToCharacterIterator, parseObject
-
Constructor Details
-
SelectFormat
Creates a newSelectFormat
for a given pattern string.- Parameters:
pattern
- the pattern for thisSelectFormat
.
-
-
Method Details
-
applyPattern
Sets the pattern used by this select format. Patterns and their interpretation are specified in the class description.- Parameters:
pattern
- the pattern for this select format.- Throws:
IllegalArgumentException
- when the pattern is not a valid select format pattern.
-
toPattern
Returns the pattern for thisSelectFormat
- Returns:
- the pattern string
-
format
Selects the phrase for the given keyword.- Parameters:
keyword
- a phrase selection keyword.- Returns:
- the string containing the formatted select message.
- Throws:
IllegalArgumentException
- when the given keyword is not a "pattern identifier"
-
format
Selects the phrase for the given keyword. and appends the formatted message to the givenStringBuffer
.- Specified by:
format
in classFormat
- Parameters:
keyword
- a phrase selection keyword.toAppendTo
- the selected phrase will be appended to thisStringBuffer
.pos
- will be ignored by this method.- Returns:
- the string buffer passed in as toAppendTo, with formatted text appended.
- Throws:
IllegalArgumentException
- when the given keyword is not a String or not a "pattern identifier"
-
parseObject
This method is not supported bySelectFormat
.- Specified by:
parseObject
in classFormat
- Parameters:
source
- the string to be parsed.pos
- defines the position where parsing is to begin, and upon return, the position where parsing left off. If the position has not changed upon return, then parsing failed.- Returns:
- nothing because this method is not supported.
- Throws:
UnsupportedOperationException
- thrown always.
-
equals
-
hashCode
public int hashCode() -
toString
-