Identify strings that need to be localized.
You can create a catalog as either a java.util.ResourceBundle subclass or a Java properties file. The properties-file approach is more common, because properties files can be prepared by people without programming experience and swapped without modifying the application code.
key = string associated with the key
Example
The following English catalog (BankingResources_en.properties) supports the labels for the list and its two list items:
accountString = Accounts savingsString = Savings checkingString = Checking
Do not create compound strings by concatenation (for example, combining the values of savingsString and accountString to form Savings Accounts in English. Success depends upon the grammar of the original language (in this case, English) and is not likely to extend to other languages. The corresponding German catalog (BankingResources_de.properties) supports the labels as follows:
accountString = Konten savingsString = Sparkonto checkingString = Girokonto
Related reference
Internationalization: Resources for learning