The Delegation model Register by invoking Trigger an event source. addXlistener(listener); User source: sourceclas listener: Listener Class Action +addXListener(LIstener listener) Keep it a list LIstener event: XEvent listener 1 Invoke listener 2 listener l handler(event) handler(XEvent event istener2. handler(event) histenern stenen handler(event) Internal function of the source object Introduction to Java Programming, revised by Dai-kaiyuLiang,Introduction to Java Programming,revised by Dai-kaiyu 9 The Delegation Model source: SourceClass +addXListener(XListener listener) User listener: ListenerClass Action Trigger an event XListener +handler(XEvent event) Internal function of the source object event: XEvent listener1 listener2 … listenern +handler( XEvent Register by invoking source.addXListener(listener); Keep it a list Invoke listener1.handler(event) listener2.handler(event) … listenern.handler(event)