001 package util;
002
003 import java.util.EventListener;
004
005 /**
006 * A listener that can be helped by ListenerHelper. HelpableListeners must use a ListenerHelper to maintain
007 * their list of listeners. Whenever a query is performed on the HelpableListener it must assure
008 * up-to-date-ness of its model by calling (@link ListenerHelper#needModelUpdate}.
009 *
010 * @see ListenerHelper
011 *
012 * @author Steffen Zschaler
013 * @version 2.0 02/06/1999
014 * @since v2.0
015 */
016 public interface HelpableListener extends EventListener {
017
018 /**
019 * Called when the listener should subscribe to its own event source.
020 *
021 * @override Always
022 */
023 public void subscribe();
024
025 /**
026 * Called when the listener should unsubscribe from its own event source.
027 *
028 * @override Always
029 */
030 public void unsubscribe();
031
032 /**
033 * Called to update the listeners own model representation.
034 *
035 * @override Always
036 */
037 public void updateModel();
038
039 }