What internationalization areas does Java support?

Joe Sam Shirah

Locales, as country, regional or area identifiers.
Localized Resources, via the ResourceBundle series of classes.
Calendars and Time Zones.
Formatting, for dates, numbers and decimals, and messages.
Text Boundaries.
Bidirectional String and Character Iteration.
Automatic Character Set Conversion.
Name and Locale Attributes for GUI Components.
Input Methods.

For further information, see: the JDK Internationalization Overview and The Java Tutorial.