“All the world’s a stage,” wrote William Shakespeare. But not all the players upon it speak the great Bard’s native tongue. To be usable on a global scale, your software needs to communicate in many different languages. The menu labels, button strings, dialog messages, title bar titles, and even command-line error messages must be settable to the user’s choice of language. This is the topic of internationalization and localization. Because these words take a long time to say and write, they are often abbreviated by their first and last letters and the count of omitted letters, that is, I18N and L10N.
Java provides a
class to discover/control the
internationalization settings. A default
inherited from operating system runtime settings when Java starts up,
and can be used most of the time!
See also the relatively new book Java Internationalization, by Andy Deitsch and David Czarnecki (O’Reilly).
 Sometimes written L9N by those who can’t count, or who think that L10N that looks too much like “lion.”