This
Callback class
represents a request for the
user's preferred language (as represented by a
Locale object), which a
LoginModule can use to localize things such as
prompts and error messages in subsequent Callback
objects. If a CallbackHandler already has
knowledge of the user's preferred langauge, it is
not required to prompt the user for this information and can simply
pass an appropriate Locale object to
setLocale( ).

public class LanguageCallback implements Callback, Serializable {
// Public Constructors
public LanguageCallback( );
// Public Instance Methods
public java.util.Locale getLocale( ); default:null
public void setLocale(java.util.Locale locale);
}