Internationalization and Locale

Locale objects are only identifiers. After defining a Locale, you pass it to other objects that perform useful tasks, such as formatting dates and numbers. These objects are locale-sensitive because their behavior varies according to Locale. A ResourceBundle is an example of a locale-sensitive object.

Locale
简单理解， 有语言和国家属性

ResourceBundle
Formatter
这些类会用到Local

还有 dates , number 也会和Locale相关。