Observerpattern (Viewer mode)

Importjava.util.ArrayList;Importjava.util.List;/*** Viewer Mode *@authorTmac-j * Reaching to describe the observer pattern in the right way * divided into pull mode and push mode, here is not detailed*/ Public classObserverpattern {Interfaceiobserved{voidAddobserver (IObserver observer); voidRemoveobserver (IObserver observer); voidnotifyobservers (); }          Public classObservedImplementsiobserved{PrivateList<iobserver> observers =NewArraylist<iobserver>(); @Override Public voidAddobserver (IObserver observer) {OBSERVERS.ADD (Observer); } @Override Public voidRemoveobserver (IObserver observer) {OBSERVERS.REMOVE (Observer); } @Override Public voidnotifyobservers () { for(IObserver observer:observers) {observer.update (); }        }            }        Interfaceiobserver{voidupdate (); }         Public classObserverImplementsiobserver{@Override Public voidUpdate () {SYSTEM.OUT.PRINTLN ("Do update ..."); }            }         Public voidTest () {iobserved observed=Newobserved (); IObserver Observer=NewObserver ();        OBSERVED.ADDOBSERVER (Observer);    Observed.notifyobservers (); }    }

Observerpattern (Viewer mode)