This interface defines no methods but serves as a "marker interface" to identify the type of objects that can be passed to the handle( ) method of a CallbackHandler . All of the classes in this package, with the exception of UnsupportedCallbackException implement this interface. public interface Callback { } ImplementationsChoiceCallback , ConfirmationCallback , LanguageCallback , NameCallback , PasswordCallback , TextInputCallback , TextOutputCallback Passed ToCallbackHandler.handle( ) , UnsupportedCallbackException.UnsupportedCallbackException( ) Returned ByUnsupportedCallbackException.getCallback( ) |