Java Watcher pattern

/***/Publicinterface  watcher    {//  status is The state public    void  update (String status) that was observed to pass over;}

Importjava.util.LinkedList;/**abstract the observed person*/ Public Abstract classwatched {/**The Observer object used to save the registration*/    protectedLinkedlist<watcher> watcherlist =NewLinkedlist<watcher>(); /**registering the Observer object*/     Public Abstract voidAdd (Watcher Watcher); /**Delete Observer Object*/     Public Abstract voidRemove (Watcher watcher); /**notifies all registered observer objects*/     Public Abstract voidnotifywatchers ();}

// the specific observer  Public class Implements Watcher {    @Override    publicvoid  update (String status) {        System.out.println ( this + "monitor status" + Status );}    }

/**specific observers: Add and Remove methods are best combined with synchronization*/ Public classGirlextendswatched {PrivateString status;  Public voidsetStatus (String status) { This. Status =status; } @Override Public synchronized voidAdd (Watcher Watcher) {Watcherlist.add (watcher); } @Override Public synchronized voidRemove (Watcher Watcher) {watcherlist.remove (watcher); } @Override Public voidnotifywatchers () { for(Watcher w:watcherlist) {w.update (status); }    }}

Test code and results

 Public classTest { Public Static voidMain (string[] args)throwsException {Girl Girl=NewGirl ();  for(inti = 0; I < 3; i++) {Girl.add (NewBoy ()); } girl.setstatus ("Happy");        Girl.notifywatchers (); TimeUnit.SECONDS.sleep (1); Girl.setstatus ("Unhappy");    Girl.notifywatchers (); }}

Reference:

Http://www.cnblogs.com/mengdd/archive/2013/02/07/2908929.html

Http://www.cnblogs.com/mengdd/archive/2013/02/07/2908929.html

Java Watcher pattern