java.util.ResourceBundle class enables you to choose and read the properties file specific to the user's locale and look up the values.
A ResourceBundle object has a base name.
In order for a ResourceBundle object to pick up a properties file, the filename must be composed of the ResourceBundle base name, followed by an underscore, followed by the language code, and optionally followed by another underscore and the country code.
The format for the properties file name is as follows:
basename_languageCode_countryCode
For example, suppose the base name is MyResources and you define the following three locales:
US-en
DE-de
CN-zh
Then you would have these three properties files:
MyResources_en_US.properties
MyResources_de_DE.properties
MyResources_zh_CN.properties