Creating a Locale

There are several ways to create a Locale object. Regardless of the technique used, creation can be as simple as specifying the language code. 有几种方法可以创建Locale对象。无论使用何种技术，创建都可以像指定语言代码一样简单。However, you can further distinguish the locale by setting the region (also referred to as "country") and variant codes. 但是，您可以通过设置地区（也称为“国家/地区”）和变体代码来进一步区分区域设置。If you are using the JDK 7 release or later, you can also specify the script code and Unicode locale extensions.如果您使用的是JDK7或更高版本，还可以指定脚本代码和Unicode区域设置扩展。

The four ways to create a Locale object are:创建Locale对象的四种方法是：

• Locale.Builder Class
• Locale Constructors
• Locale.forLanguageTag Factory Method
• Locale Constants

LocaleBuilder Class

The Locale.Builder utility class can be used to construct a Locale object that conforms to the IETF BCP 47 syntax. For example, to specify the French language and the country of Canada, you could invoke the Locale.Builder constructor and then chain the setter methods as follows:

Locale aLocale = new Locale.Builder().setLanguage("fr").setRegion("CA").build();

The next example creates Locale objects for the English language in the United States and Great Britain:下一个示例为美国和英国的英语创建Locale对象：

Locale bLocale = new Locale.Builder().setLanguage("en").setRegion("US").build();
Locale cLocale = new Locale.Builder().setLanguage("en").setRegion("GB").build();

The final example creates a Locale object for the Russian language:最后一个示例为俄语创建一个Locale对象：

Locale dLocale = new Locale.Builder().setLanguage("ru").setScript("Cyrl").build();

Locale Constructors

There are three constructors available in the Locale class for creating a Locale object:

• Locale(String language)
• Locale(String language, String country)
• Locale(String language, String country, String variant)

The following examples create Locale objects for the French language in Canada, the English language in the U.S. and Great Britain, and the Russian language.

aLocale = new Locale("fr", "CA");
bLocale = new Locale("en", "US");
cLocale = new Locale("en", "GB");
dLocale = new Locale("ru");

It is not possible to set a script code on a Locale object in a release earlier than JDK 7.

forLanguageTag Factory Method

If you have a language tag string that conforms to the IETF BCP 47 standard, you can use the forLanguageTag(String) factory method, which was introduced in the Java SE 7 release. For example:

Locale aLocale = Locale.forLanguageTag("en-US");
Locale bLocale = Locale.forLanguageTag("ja-JP-u-ca-japanese");

Locale Constants

For your convenience the Locale class provides constants for some languages and countries. For example:

cLocale = Locale.JAPAN;
dLocale = Locale.CANADA_FRENCH;

When you specify a language constant, the region portion of the Locale is undefined. The next three statements create equivalent Locale objects:

j1Locale = Locale.JAPANESE;
j2Locale = new Locale.Builder().setLanguage("ja").build();
j3Locale = new Locale("ja");

The Locale objects created by the following three statements are also equivalent:

j4Locale = Locale.JAPAN;
j5Locale = new Locale.Builder().setLanguage("ja").setRegion("JP").build();
j6Locale = new Locale("ja", "JP");

Codes

The following sections discuss the language code and the optional script, region, and variant codes.

Language Code

The language code is either two or three lowercase letters that conform to the ISO 639 standard. You can find a full list of the ISO 639 codes at http://www.loc.gov/standards/iso639-2/php/code_list.php.

The following table lists a few of the language codes.

Script Code

The script code begins with an uppercase letter followed by three lowercase letters and conforms to the ISO 15924 standard. You can find a full list of the ISO 15924 codes at http://unicode.org/iso15924/iso15924-codes.html.

The following table lists a few of the script codes.

There are three methods for retrieving the script information for a Locale:

• getScript() – returns the 4-letter script code for a Locale object. If no script is defined for the locale, an empty string is returned.
• getDisplayScript() – returns a name for the locale's script that is appropriate for display to the user. If possible, the name will be localized for the default locale. So, for example, if the script code is "Latn," the display script name returned would be the string "Latin" for an English language locale.
• getDisplayScript(Locale) – returns the display name of the specified Locale localized, if possible, for the locale.

Region Code

The region (country) code consists of either two or three uppercase letters that conform to the ISO 3166 standard, or three numbers that conform to the UN M.49 standard. A copy of the codes can be found at http://www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html.

The following table contains several sample country and region codes.

Variant Code

The optional variant code can be used to further distinguish your Locale. For example, the variant code can be used to indicate dialectical differences that are not covered by the region code.

As of the Java SE 7 release, which conforms to the IETF BCP 47 standard, the variant code is used specifically to indicate additional variations that define a language or its dialects. The IETF BCP 47 standard imposes syntactic restrictions on the variant subtag. You can see a list of variant codes (search for variant) at http://www.iana.org/assignments/language-subtag-registry.

For example, Java SE uses the variant code to support the Thai language. By convention, a NumberFormat object for the th and th_TH locales will use common Arabic digit shapes, or Arabic numerals, to format Thai numbers. However, a NumberFormat for the th_TH_TH locale uses Thai digit shapes. The excerpt from ThaiDigits.java demonstrates this:

String outputString = new String();
Locale[] thaiLocale = {
             new Locale("th"),
             new Locale("th", "TH"),
             new Locale("th", "TH", "TH")
         };

for (Locale locale : thaiLocale) {
    NumberFormat nf = NumberFormat.getNumberInstance(locale);
    outputString = outputString + locale.toString() + ": ";
    outputString = outputString + nf.format(573.34) + "\n";
}

The following is a screenshot of this sample: