Isolating Locale-Specific Data
Trail: Internationalization

Lesson: Isolating Locale-Specific Data

Locale-specific data must be tailored according to the conventions of the end user's language and region. The text displayed by a user interface is the most obvious example of locale-specific data. For example, an application with a Cancel button in the U.S. will have an Abbrechen button in Germany. In other countries this button will have other labels. Obviously you don't want to hardcode this button label. Wouldn't it be nice if you could automatically get the correct label for a given Locale? Fortunately you can, provided that you isolate the locale-specific objects in a ResourceBundle.

In this lesson you'll learn how to create and access ResourceBundle objects. If you're in a hurry to examine some coding examples, go ahead and check out the last two sections in this lesson. Then you can come back to the first two sections to get some conceptual information about ResourceBundle objects.

About the ResourceBundle Class

ResourceBundle objects contain locale-specific objects. When you need a locale-specific object, you fetch it from a ResourceBundle, which returns the object that matches the end user's Locale. This section explains how a ResourceBundle is related to a Locale, and describes the ResourceBundle subclasses.

Preparing to Use a ResourceBundle

Before you create your ResourceBundle objects, you should do a little planning. First, identify the locale-specific objects in your program. Then organize them into categories and store them in different ResourceBundle objects accordingly.

Backing a ResourceBundle with Properties Files

If your application contains String objects that need to be translated into various languages, you can store these String objects in a PropertyResourceBundle, which is backed up by a set of properties files. Since the properties files are simple text files, they can be created and maintained by your translators. You don't have to change the source code. In this section you'll learn how to set up the properties files that back up a PropertyResourceBundle.

Using a ListResourceBundle

The ListResourceBundle class, which is a subclass of ResourceBundle, manages locale-specific objects with a list. A ListResourceBundle is backed by a class file, which means that you must code and compile a new source file each time support for an additional Locale is needed. However, ListResourceBundle objects are useful because unlike properties files, they can store any type of locale-specific object. By stepping through a sample program, this section demonstrates how to use a ListResourceBundle.

Customizing Resource Bundle Loading

This section represents new capabilities to improve the ResourceBundle.getBundle factory flexibility. The ResourceBundle.Control class collaborates with the factory methods for loading resource bundles. This allows to consider every substantial step of the resource bundle-loading process and its cache control as a separate method.

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