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FlexDoc/Javadoc 2.0 Demo Java Doc |
The Locale class implements IETF BCP 47 which is composed of RFC 4647 "Matching of Language Tags" and RFC 5646 "Tags for Identifying Languages" with support for the LDML (UTS#35, "Unicode Locale Data Markup Language") BCP 47-compatible extensions for locale data exchange.
A Locale object logically consists of the fields described below.
[a-zA-Z]{2,8}
. Note that this is not the full
BCP47 language production, since it excludes extlang. They are
not needed since modern three-letter language codes replace
them.[a-zA-Z]{4}
[a-zA-Z]{2} | [0-9]{3}
However, the variant field in Locale has historically been used for any kind of variation, not just language variations. For example, some supported variants available in Java SE Runtime Environments indicate alternative cultural behaviors such as calendar type or number script. In BCP 47 this kind of information, which does not identify the language, is supported by extension subtags or private use subtags.
SUBTAG
(('_'|'-') SUBTAG)*
where SUBTAG =
[0-9][0-9a-zA-Z]{3} | [0-9a-zA-Z]{5,8}
. (Note: BCP 47 only
uses hyphen ('-') as a delimiter, this is more lenient).SUBTAG = [0-9a-zA-Z]{1,8}
and for other keys
SUBTAG = [0-9a-zA-Z]{2,8}
(that is, 'x' allows
single-character subtags).UTS#35, "Unicode Locale Data Markup Language" defines optional attributes and keywords to override or refine the default behavior associated with a locale. A keyword is represented by a pair of key and type. For example, "nu-thai" indicates that Thai local digits (value:"thai") should be used for formatting numbers (key:"nu").
The keywords are mapped to a BCP 47 extension value using the extension key 'u' (UNICODE_LOCALE_EXTENSION). The above example, "nu-thai", becomes the extension "u-nu-thai".
Thus, when a Locale object contains Unicode locale attributes and keywords, getExtension(UNICODE_LOCALE_EXTENSION) will return a String representing this information, for example, "nu-thai". The Locale class also provides getUnicodeLocaleAttributes(), getUnicodeLocaleKeys(), and getUnicodeLocaleType(String) which allow you to access Unicode locale attributes and key/type pairs directly. When represented as a string, the Unicode Locale Extension lists attributes alphabetically, followed by key/type sequences with keys listed alphabetically (the order of subtags comprising a key's type is fixed when the type is defined)
A well-formed locale key has the form
[0-9a-zA-Z]{2}
. A well-formed locale type has the
form "" | [0-9a-zA-Z]{3,8} ('-' [0-9a-zA-Z]{3,8})*
(it
can be empty, or a series of subtags 3-8 alphanums in length). A
well-formed locale attribute has the form
[0-9a-zA-Z]{3,8}
(it is a single subtag with the same
form as a locale type subtag).
The Unicode locale extension specifies optional behavior in locale-sensitive services. Although the LDML specification defines various keys and values, actual locale-sensitive service implementations in a Java Runtime Environment might not support any particular Unicode locale attributes or key/type pairs.
There are several different ways to create a Locale object.
Using Locale.Builder you can construct a Locale object that conforms to BCP 47 syntax.
The Locale class provides three constructors:
These constructors allow you to create a Locale object with language, country and variant, but you cannot specify script or extensions.Locale(String language) Locale(String language, String country) Locale(String language, String country, String variant)
The method forLanguageTag(String) creates a Locale object for a well-formed BCP 47 language tag.
The Locale class provides a number of convenient constants that you can use to create Locale objects for commonly used locales. For example, the following creates a Locale object for the United States:
Locale.US
If an application or a system is internationalized and provides localized resources for multiple locales, it sometimes needs to find one or more locales (or language tags) which meet each user's specific preferences. Note that a term "language tag" is used interchangeably with "locale" in this locale matching documentation.
In order to do matching a user's preferred locales to a set of language tags, RFC 4647 Matching of Language Tags defines two mechanisms: filtering and lookup. Filtering is used to get all matching locales, whereas lookup is to choose the best matching locale. Matching is done case-insensitively. These matching mechanisms are described in the following sections.
A user's preference is called a Language Priority List and is expressed as a list of language ranges. There are syntactically two types of language ranges: basic and extended. See Locale.LanguageRange for details.
The filtering operation returns all matching language tags. It is defined in RFC 4647 as follows: "In filtering, each language range represents the least specific language tag (that is, the language tag with fewest number of subtags) that is an acceptable match. All of the language tags in the matching set of tags will have an equal or greater number of subtags than the language range. Every non-wildcard subtag in the language range will appear in every one of the matching language tags."
There are two types of filtering: filtering for basic language ranges (called "basic filtering") and filtering for extended language ranges (called "extended filtering"). They may return different results by what kind of language ranges are included in the given Language Priority List. Locale.FilteringMode is a parameter to specify how filtering should be done.
The lookup operation returns the best matching language tags. It is defined in RFC 4647 as follows: "By contrast with filtering, each language range represents the most specific tag that is an acceptable match. The first matching tag found, according to the user's priority, is considered the closest match and is the item returned."
For example, if a Language Priority List consists of two language ranges, "zh-Hant-TW" and "en-US", in prioritized order, lookup method progressively searches the language tags below in order to find the best matching language tag.
If there is a language tag which matches completely to a language range above, the language tag is returned.1. zh-Hant-TW 2. zh-Hant 3. zh 4. en-US 5. en
"*" is the special language range, and it is ignored in lookup.
If multiple language tags match as a result of the subtag '*' included in a language range, the first matching language tag returned by an Iterator over a Collection of language tags is treated as the best matching one.
Once you've created a Locale you can query it for information about itself. Use getCountry to get the country (or region) code and getLanguage to get the language code. You can use getDisplayCountry to get the name of the country suitable for displaying to the user. Similarly, you can use getDisplayLanguage to get the name of the language suitable for displaying to the user. Interestingly, the getDisplayXXX methods are themselves locale-sensitive and have two versions: one that uses the default DISPLAY locale and one that uses the locale specified as an argument.
The Java Platform provides a number of classes that perform locale-sensitive operations. For example, the NumberFormat class formats numbers, currency, and percentages in a locale-sensitive manner. Classes such as NumberFormat have several convenience methods for creating a default object of that type. For example, the NumberFormat class provides these three convenience methods for creating a default NumberFormat object:
Each of these methods has two variants; one with an explicit locale and one without; the latter uses the default FORMAT locale:NumberFormat.getInstance() NumberFormat.getCurrencyInstance() NumberFormat.getPercentInstance()
A Locale is the mechanism for identifying the kind of object (NumberFormat) that you would like to get. The locale is just a mechanism for identifying objects, not a container for the objects themselves.NumberFormat.getInstance(myLocale) NumberFormat.getCurrencyInstance(myLocale) NumberFormat.getPercentInstance(myLocale)
In order to maintain compatibility with existing usage, Locale's constructors retain their behavior prior to the Java Runtime Environment version 1.7. The same is largely true for the toString method. Thus Locale objects can continue to be used as they were. In particular, clients who parse the output of toString into language, country, and variant fields can continue to do so (although this is strongly discouraged), although the variant field will have additional information in it if script or extensions are present.
In addition, BCP 47 imposes syntax restrictions that are not imposed by Locale's constructors. This means that conversions between some Locales and BCP 47 language tags cannot be made without losing information. Thus toLanguageTag cannot represent the state of locales whose language, country, or variant do not conform to BCP 47.
Because of these issues, it is recommended that clients migrate away from constructing non-conforming locales and use the forLanguageTag and Locale.Builder APIs instead. Clients desiring a string representation of the complete locale can then always rely on toLanguageTag for this purpose.
For compatibility reasons, two non-conforming locales are treated as special cases. These are ja_JP_JP and th_TH_TH. These are ill-formed in BCP 47 since the variants are too short. To ease migration to BCP 47, these are treated specially during construction. These two cases (and only these) cause a constructor to generate an extension, all other values behave exactly as they did prior to Java 7.
Java has used ja_JP_JP to represent Japanese as used in Japan together with the Japanese Imperial calendar. This is now representable using a Unicode locale extension, by specifying the Unicode locale key ca (for "calendar") and type japanese. When the Locale constructor is called with the arguments "ja", "JP", "JP", the extension "u-ca-japanese" is automatically added.
Java has used th_TH_TH to represent Thai as used in Thailand together with Thai digits. This is also now representable using a Unicode locale extension, by specifying the Unicode locale key nu (for "number") and value thai. When the Locale constructor is called with the arguments "th", "TH", "TH", the extension "u-nu-thai" is automatically added.
During serialization, writeObject writes all fields to the output stream, including extensions.
During deserialization, readResolve adds extensions as described in Special Cases, only for the two cases th_TH_TH and ja_JP_JP.
Locale's constructor has always converted three language codes to their earlier, obsoleted forms: he maps to iw, yi maps to ji, and id maps to in. Since Java SE 17, this is no longer the case. Each language maps to its new form; iw maps to he, ji maps to yi, and in maps to id.
For the backward compatible behavior, the system property java.locale.useOldISOCodes reverts the behavior back to that of before Java SE 17. If the system property is set to true, those three current language codes are mapped to their backward compatible forms. The property is only read at Java runtime startup and subsequent calls to System.setProperty() will have no effect.
The APIs added in 1.7 map between the old and new language codes, maintaining the mapped codes internal to Locale (so that getLanguage and toString reflect the mapped code, which depends on the java.locale.useOldISOCodes system property), but using the new codes in the BCP 47 language tag APIs (so that toLanguageTag reflects the new one). This preserves the equivalence between Locales no matter which code or API is used to construct them. Java's default resource bundle lookup mechanism also implements this mapping, so that resources can be named using either convention, see ResourceBundle.Control.
The Locale constructors have always specified that the language and the country param be two characters in length, although in practice they have accepted any length. The specification has now been relaxed to allow language codes of two to eight characters and country (region) codes of two to three characters, and in particular, three-letter language codes and three-digit region codes as specified in the IANA Language Subtag Registry. For compatibility, the implementation still does not impose a length constraint.
Nested Class Summary |
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static class |
Builder is used to build instances of Locale
from values configured by the setters.
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static enum |
Enum for locale categories.
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static enum |
This enum provides constants to select a filtering mode for locale
matching.
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static enum |
Enum for specifying the type defined in ISO 3166.
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static class |
This class expresses a Language Range defined in
RFC 4647 Matching of
Language Tags.
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Field Summary |
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final char |
The key for the private use extension ('x').
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static final Locale |
Useful constant for the root locale.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final Locale |
Useful constant for language.
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static final Locale |
Useful constant for country.
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static final char |
The key for Unicode locale extension ('u').
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static final Locale |
Useful constant for country.
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Constructor Summary |
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Construct a locale from a language code.
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Construct a locale from language and country.
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Construct a locale from language, country and variant.
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Method Summary |
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clone()
Overrides Cloneable.
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boolean |
Returns true if this Locale is equal to another object.
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Returns a list of matching Locale instances using the filtering
mechanism defined in RFC 4647.
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filter(List<Locale.LanguageRange> priorityList, Collection<Locale> locales, Locale.FilteringMode mode)
Returns a list of matching Locale instances using the filtering
mechanism defined in RFC 4647.
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Returns a list of matching languages tags using the basic filtering
mechanism defined in RFC 4647.
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filterTags(List<Locale.LanguageRange> priorityList, Collection<String> tags, Locale.FilteringMode mode)
Returns a list of matching languages tags using the basic filtering
mechanism defined in RFC 4647.
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static Locale |
forLanguageTag(String languageTag)
Returns a locale for the specified IETF BCP 47 language tag string.
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static Locale[] |
Returns an array of all installed locales.
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Returns the country/region code for this locale, which should
either be the empty string, an uppercase ISO 3166 2-letter code,
or a UN M.49 3-digit code.
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static Locale |
Gets the current value of the default locale for this instance
of the Java Virtual Machine.
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static Locale |
getDefault(Locale.Category category)
Gets the current value of the default locale for the specified Category
for this instance of the Java Virtual Machine.
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final String |
Returns a name for the locale's country that is appropriate for display to the
user.
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getDisplayCountry(Locale inLocale)
Returns a name for the locale's country that is appropriate for display to the
user.
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final String |
Returns a name for the locale's language that is appropriate for display to the
user.
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getDisplayLanguage(Locale inLocale)
Returns a name for the locale's language that is appropriate for display to the
user.
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final String |
Returns a name for the locale that is appropriate for display to the
user.
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getDisplayName(Locale inLocale)
Returns a name for the locale that is appropriate for display
to the user.
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Returns a name for the locale's script that is appropriate for display to
the user.
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getDisplayScript(Locale inLocale)
Returns a name for the locale's script that is appropriate
for display to the user.
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final String |
Returns a name for the locale's variant code that is appropriate for display to the
user.
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getDisplayVariant(Locale inLocale)
Returns a name for the locale's variant code that is appropriate for display to the
user.
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getExtension(char key)
Returns the extension (or private use) value associated with
the specified key, or null if there is no extension
associated with the key.
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Returns the set of extension keys associated with this locale, or the
empty set if it has no extensions.
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Returns a three-letter abbreviation for this locale's country.
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Returns a three-letter abbreviation of this locale's language.
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static String[] |
Returns a list of all 2-letter country codes defined in ISO 3166.
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Returns a Set of ISO3166 country codes for the specified type.
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static String[] |
Returns a list of all 2-letter language codes defined in ISO 639.
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Returns the language code of this Locale.
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Returns the script for this locale, which should
either be the empty string or an ISO 15924 4-letter script
code.
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Returns the set of unicode locale attributes associated with
this locale, or the empty set if it has no attributes.
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Returns the set of Unicode locale keys defined by this locale, or the empty set if
this locale has none.
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Returns the Unicode locale type associated with the specified Unicode locale key
for this locale.
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Returns the variant code for this locale.
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boolean |
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int |
hashCode()
Override hashCode.
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static Locale |
Returns a Locale instance for the best-matching language
tag using the lookup mechanism defined in RFC 4647.
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static String |
Returns the best-matching language tag using the lookup mechanism
defined in RFC 4647.
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static void |
setDefault(Locale newLocale)
Sets the default locale for this instance of the Java Virtual Machine.
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static void |
Sets the default locale for the specified Category for this instance
of the Java Virtual Machine.
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Returns a copy of this Locale with no
extensions.
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Returns a well-formed IETF BCP 47 language tag representing
this locale.
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final String |
toString()
Returns a string representation of this Locale
object, consisting of language, country, variant, script,
and extensions as below:
language + "_" + country + "_" + (variant + "_#" | "#") + script + "_" + extensions
Language is always lower case, country is always upper case, script is always title
case, and extensions are always lower case.
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Methods inherited from class java.lang.Object |
public Locale |
public Locale |
public Locale |
(String language) |
public static Locale getDefault |
() |
The Java Virtual Machine sets the default locale during startup based on the host environment. It is used by many locale-sensitive methods if no locale is explicitly specified. It can be changed using the setDefault method.
public static Locale getDefault |
(Locale.Category category) |
The Java Virtual Machine sets the default locale during startup based on the host environment. It is used by many locale-sensitive methods if no locale is explicitly specified. It can be changed using the setDefault(Locale.Category, Locale) method.
public static void setDefault |
(Locale newLocale) |
If there is a security manager, its checkPermission method is called with a PropertyPermission("user.language", "write") permission before the default locale is changed.
The Java Virtual Machine sets the default locale during startup based on the host environment. It is used by many locale-sensitive methods if no locale is explicitly specified.
Since changing the default locale may affect many different areas of functionality, this method should only be used if the caller is prepared to reinitialize locale-sensitive code running within the same Java Virtual Machine.
By setting the default locale with this method, all of the default locales for each Category are also set to the specified default locale.
public static void setDefault |
If there is a security manager, its checkPermission method is called with a PropertyPermission("user.language", "write") permission before the default locale is changed.
The Java Virtual Machine sets the default locale during startup based on the host environment. It is used by many locale-sensitive methods if no locale is explicitly specified.
Since changing the default locale may affect many different areas of functionality, this method should only be used if the caller is prepared to reinitialize locale-sensitive code running within the same Java Virtual Machine.
public static Locale[] getAvailableLocales |
() |
public static String[] getISOCountries |
() |
Note: The Locale class also supports other codes for country (region), such as 3-letter numeric UN M.49 area codes. Therefore, the list returned by this method does not contain ALL valid codes that can be used to create Locales.
Note that this method does not return obsolete 2-letter country codes. ISO3166-3 codes which designate country codes for those obsolete codes, can be retrieved from getISOCountries(Locale.IsoCountryCode type) with type Locale.IsoCountryCode.PART3.
(Locale.IsoCountryCode type) |
public static String[] getISOLanguages |
() |
Note:
public String getLanguage |
() |
public String getScript |
() |
public String getCountry |
() |
public String getVariant |
() |
public boolean hasExtensions |
() |
public Locale stripExtensions |
() |
public String getExtension |
(char key) |
() |
() |
public String getUnicodeLocaleType |
(String key) |
() |
public final String toString |
() |
language + "_" + country + "_" + (variant + "_#" | "#") + script + "_" + extensionsLanguage is always lower case, country is always upper case, script is always title case, and extensions are always lower case. Extensions and private use subtags will be in canonical order as explained in toLanguageTag().
When the locale has neither script nor extensions, the result is the same as in Java 6 and prior.
If both the language and country fields are missing, this function will return the empty string, even if the variant, script, or extensions field is present (you can't have a locale with just a variant, the variant must accompany a well-formed language or country code).
If script or extensions are present and variant is missing, no underscore is added before the "#".
This behavior is designed to support debugging and to be compatible with previous uses of toString that expected language, country, and variant fields only. To represent a Locale as a String for interchange purposes, use toLanguageTag().
Examples:
public String toLanguageTag |
() |
If this Locale has a language, country, or variant that does not satisfy the IETF BCP 47 language tag syntax requirements, this method handles these fields as described below:
Language: If language is empty, or not well-formed (for example "a" or "e2"), it will be emitted as "und" (Undetermined).
Country: If country is not well-formed (for example "12" or "USA"), it will be omitted.
Variant: If variant is well-formed, each sub-segment (delimited by '-' or '_') is emitted as a subtag. Otherwise:
[0-9a-zA-Z]{1,8}
(for example "WIN" or "Oracle_JDK_Standard_Edition"), the first
ill-formed sub-segment and all following will be appended to
the private use subtag. The first appended subtag will be
"lvariant", followed by the sub-segments in order, separated by
hyphen. For example, "x-lvariant-WIN",
"Oracle-x-lvariant-JDK-Standard-Edition".
[0-9a-zA-Z]{1,8}
, the variant will be truncated
and the problematic sub-segment and all following sub-segments
will be omitted. If the remainder is non-empty, it will be
emitted as a private use subtag as above (even if the remainder
turns out to be well-formed). For example,
"Solaris_isjustthecoolestthing" is emitted as
"x-lvariant-Solaris", not as "solaris".Special Conversions: Java supports some old locale representations, including deprecated ISO language codes, for compatibility. This method performs the following conversions:
Note: Although the language tag created by this method is well-formed (satisfies the syntax requirements defined by the IETF BCP 47 specification), it is not necessarily a valid BCP 47 language tag. For example,
new Locale("xx", "YY").toLanguageTag();will return "xx-YY", but the language subtag "xx" and the region subtag "YY" are invalid because they are not registered in the IANA Language Subtag Registry.
public static Locale forLanguageTag |
(String languageTag) |
If the specified language tag contains any ill-formed subtags, the first such subtag and all following subtags are ignored. Compare to Locale.Builder.setLanguageTag(String) which throws an exception in this case.
The following conversions are performed:
Locale loc; loc = Locale.forLanguageTag("en-US-x-lvariant-POSIX"); loc.getVariant(); // returns "POSIX" loc.getExtension('x'); // returns null loc = Locale.forLanguageTag("de-POSIX-x-URP-lvariant-Abc-Def"); loc.getVariant(); // returns "POSIX_Abc_Def" loc.getExtension('x'); // returns "urp"
Locale.forLanguageTag("ar-aao").getLanguage(); // returns "aao" Locale.forLanguageTag("en-abc-def-us").toString(); // returns "abc_US"
Locale.forLanguageTag("ja-JP-x-lvariant-JP").toLanguageTag(); // returns "ja-JP-u-ca-japanese-x-lvariant-JP" Locale.forLanguageTag("th-TH-x-lvariant-TH").toLanguageTag(); // returns "th-TH-u-nu-thai-x-lvariant-TH"
This implements the 'Language-Tag' production of BCP47, and so supports legacy (regular and irregular, referred to as "Type: grandfathered" in BCP47) as well as private use language tags. Stand alone private use tags are represented as empty language and extension 'x-whatever', and legacy tags are converted to their canonical replacements where they exist.
Legacy tags with canonical replacements are as follows:
legacy tag | modern replacement |
---|---|
art-lojban | jbo |
i-ami | ami |
i-bnn | bnn |
i-hak | hak |
i-klingon | tlh |
i-lux | lb |
i-navajo | nv |
i-pwn | pwn |
i-tao | tao |
i-tay | tay |
i-tsu | tsu |
no-bok | nb |
no-nyn | nn |
sgn-BE-FR | sfb |
sgn-BE-NL | vgt |
sgn-CH-DE | sgg |
zh-guoyu | cmn |
zh-hakka | hak |
zh-min-nan | nan |
zh-xiang | hsn |
Legacy tags with no modern replacement will be converted as follows:
legacy tag | converts to |
---|---|
cel-gaulish | xtg-x-cel-gaulish |
en-GB-oed | en-GB-x-oed |
i-default | en-x-i-default |
i-enochian | und-x-i-enochian |
i-mingo | see-x-i-mingo |
zh-min | nan-x-zh-min |
For a list of all legacy tags, see the IANA Language Subtag Registry (search for "Type: grandfathered").
Note: there is no guarantee that toLanguageTag and forLanguageTag will round-trip.
public String getISO3Language |
() |
throws |
public String getISO3Country |
() |
throws |
The ISO 3166-1 codes can be found on-line.
public final String getDisplayLanguage |
() |
public String getDisplayLanguage |
(Locale inLocale) |
public String getDisplayScript |
() |
public String getDisplayScript |
(Locale inLocale) |
public final String getDisplayCountry |
() |
public String getDisplayCountry |
(Locale inLocale) |
public final String getDisplayVariant |
() |
public String getDisplayVariant |
(Locale inLocale) |
public final String getDisplayName |
() |
language (script, country, variant(, extension)*)depending on which fields are specified in the locale. The field separator in the above parentheses, denoted as a comma character, may be localized depending on the locale. If the language, script, country, and variant fields are all empty, this function returns the empty string.
language (country(, extension)*)
language (variant(, extension)*)
script (country(, extension)*)
country (extension)*
public String getDisplayName |
(Locale inLocale) |
language (script, country, variant(, extension)*)depending on which fields are specified in the locale. The field separator in the above parentheses, denoted as a comma character, may be localized depending on the locale. If the language, script, country, and variant fields are all empty, this function returns the empty string.
language (country(, extension)*)
language (variant(, extension)*)
script (country(, extension)*)
country (extension)*
public Object clone |
() |
public int hashCode |
() |
public boolean equals |
(Object obj) |
public static Locale lookup |
public static String lookupTag |
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