Preparing to Use a ResourceBundle
If your application has a user interface, it contains many locale-specific objects. To get started, you should go through your source code and look for objects that vary with
Locale . Your list might include objects instantiated from the following classes:
You'll notice that this list doesn't contain objects representing numbers, dates, times, or currencies. The display format of these objects varies with
Locale , but the objects themselves do not. For example, you format a
Date according to
Locale , but you use the same
Date object regardless of
Locale . Instead of isolating these objects in a
ResourceBundle , you format them with special locale-sensitive formatting classes. You'll learn how to do this in the Dates and Times section of the Formatting lesson.
In general, the objects stored in a
ResourceBundle are predefined and ship with the product. These objects are not modified while the program is running. For instance, you should store a
Menu label in a
ResourceBundle because it is locale-specific and will not change during the program session. However, you should not isolate in a
String object the end user enters in a
TextField . Data such as this
String may vary from day to day. It is specific to the program session, not to the
Locale in which the program runs.
Usually most of the objects you need to isolate in a
String objects. However, not all
String objects are locale-specific. For example, if a
String is a protocol element used by interprocess communication, it doesn't need to be localized, because the end users never see it.
The decision whether to localize some
String objects is not always clear. Log files are a good example. If a log file is written by one program and read by another, both programs are using the log file as a buffer for communication. Suppose that end users occasionally check the contents of this log file. Shouldn't the log file be localized? On the other hand, if end users rarely check the log file, the cost of translation may not be worthwhile. Your decision to localize this log file depends on a number of factors: program design, ease of use, cost of translation, and supportability.
You can organize your
ResourceBundle objects according to the category of objects they contain. For example, you might want to load all of the GUI labels for an order entry window into a
OrderLabelsBundle . Using multiple
ResourceBundle objects offers several advantages:
Your code is easier to read and to maintain.
You'll avoid huge
ResourceBundleobjects, which may take too long to load into memory.
You can reduce memory usage by loading each
ResourceBundleonly when needed.