java.util.Locale

A Locale object represents a specific geographical, political, or cultural region. An operation that requires a Locale to perform its task is called locale-sensitive and uses the Locale to tailor information for the user. For example, displaying a number is a locale-sensitive operation--the number should be formatted according to the customs/conventions of the user's native country, region, or culture.

Create a Locale object using the constructors in this class:

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

The language argument is a valid ISO Language Code. These codes are the lower-case, two-letter codes as defined by ISO-639. You can find a full list of these codes at a number of sites, such as:
http://www.loc.gov/standards/iso639-2/englangn.html

The country argument is a valid ISO Country Code. These codes are the upper-case, two-letter codes as defined by ISO-3166. You can find a full list of these codes at a number of sites, such as:
http://www.iso.ch/iso/en/prods-services/iso3166ma/02iso-3166-code-lists/list-en1.html

The variant argument is a vendor or browser-specific code. For example, use WIN for Windows, MAC for Macintosh, and POSIX for POSIX. Where there are two variants, separate them with an underscore, and put the most important one first. For example, a Traditional Spanish collation might construct a locale with parameters for language, country and variant as: "es", "ES", "Traditional_WIN".

Because a Locale object is just an identifier for a region, no validity check is performed when you construct a Locale. If you want to see whether particular resources are available for the Locale you construct, you must query those resources. For example, ask the NumberFormat for the locales it supports using its getAvailableLocales method.

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 locale = Locale.US
 

Once you've created a Locale you can query it for information about itself. Use getCountry to get the ISO Country Code and getLanguage to get the ISO 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 locale and one that uses the locale specified as an argument.

You can get the current value of the default locale for this instance of the Java Virtual Machine by using the static getDefault() method.  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 static setDefault method.

The Java 2 platform provides a number of classes that perform locale-sensitive operations. For example, the NumberFormat class formats numbers, currency, or percentages in a locale-sensitive manner. Classes such as NumberFormat have a number of 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:

 NumberFormat.getInstance()
 NumberFormat.getCurrencyInstance()
 NumberFormat.getPercentInstance()
 

These methods have two variants; one with an explicit locale and one without; the latter using the default locale.

 NumberFormat.getInstance(myLocale)
 NumberFormat.getCurrencyInstance(myLocale)
 NumberFormat.getPercentInstance(myLocale)
 

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.