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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, load, 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. In this section, we'll explain how a ResourceBundle is related to a Locale. We'll also describe the ResourceBundle subclasses, and when you should use them.

Preparing to Use a ResourceBundle

Before you create and load your ResourceBundle objects, you should do a little planning. First, identify the locale-specific objects in your program. Then, organize these locale-specific objects 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 different languages, you should 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 aPropertyResourceBundle.

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 you must code and compile an new source file each time support for an additional Locale is needed. Therefore, you should not use a ListResourceBundle to isolate String objects that must be translated into other languages. Instead, you use a PropertyResourceBundle because it is backed up by a set of editable properties files. However, ListResourceBundle objects are useful, because unlike properties files, they can store any type of locale-specific object. By stepping through an example program, this section demonstrates how to use a ListResourceBundle.

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