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Setting the Locale
Trail: Internationalization

Lesson: Setting the Locale

An internationalized program can display information differently throughout the world. For example, the program will display different messages in Paris, Tokyo, and New York. If the localization process has been fine-tuned, the program will display different messages in New York and London to account for the differences between American and British English. How does an internationalized program identify the appropriate language and region of its end users? Easy. It references a Locale object.

A Locale object is an identifier for a particular combination of language and region. If a class varies its behavior according to Locale, it is said to be locale-sensitive. For example, the NumberFormat class is locale-sensitive; the format of the number it returns depends on the Locale. Thus NumberFormat may return a number as 902 300 (France), or 902.300 (Germany), or 902,300 (United States). Locale objects are only identifiers. The real work, such as formatting and detecting word boundaries, is performed by the methods of the locale-sensitive classes.

The following sections explain how to work with Locale objects:

Creating a Locale

When creating a Locale object, you usually specify a language code and a country code. A third parameter, the variant, is optional.

BCP 47 Extensions

This section shows you how to add a Unicode locale extension or a private use extension to a Locale.

Identifying Available Locales

Locale-sensitive classes support only certain Locale definitions. This section shows you how to determine which Locale definitions are supported.

Language Tag Filtering and Lookup

This section describes the internationalization support for language tags, language tags filtering, and language tags lookup.

The Scope of a Locale

On the Java platform you do not specify a global Locale by setting an environment variable before running the application. Instead you either rely on the default Locale or assign a Locale to each locale-sensitive object.

Locale-Sensitive Services SPI

This section explains how to enable plug-in of locale-dependent data and services. These SPIs (Service Provider Interface) provides support of more locales in addition to the currently available locales.

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