In the Java 2 platform, java.util.Locale represents a specific geographical, political, or cultural region. The string representation of a locale consists of the international standard two-character abbreviation for language and country and an optional variant, all separated by underscore (_) characters. Examples of locale strings include fr (French), de_CH (Swiss German), and en_US_POSIX (English on a POSIX-compliant platform).
Locale-sensitive data is stored in a java.util.ResourceBundle. A resource bundle contains key-value pairs, where the keys uniquely identify a locale-specific object in the bundle. A resource bundle can be backed by a text file (properties resource bundle) or a class (list resource bundle) containing the pairs. You construct resource bundle instance by appending a locale string representation to a base name.
For more details on internationalization and localization in the Java 2 platform, see http://java.sun.com/docs/books/tutorial/i18n/index.html.
In the web technology chapters, the Duke’s Bookstore applications contain resource bundles with the base name messages.BookstoreMessages for the locales en_US, fr_FR, de_DE, and es_MX.