Design patterns - Observer Pattern
8
OBSERVER PATTERN explained ! Prepared by Annamalai Copyright 2006-2011 QmPe initiative
-
Upload
annamalai-c -
Category
Technology
-
view
867 -
download
1
description
Transcript of Design patterns - Observer Pattern
OBSERVER PATTERN explained !
Prepared by Annamalai C
Copyright 2006-2011
QmPeinitiative
Copyright 2006-2011
Observer Pattern in Real Life
There is always a Observer and Observable object around you.You are an Observer, TV is an Observable Object.-----------------------------------Ideology of Observer Pattern is something close.-----------------------------------Colloquially Observers are called as Listeners Observables are called as Providers
ObserverObservable
Copyright 2006-2011
Observer Pattern in Java
Observable Objects are called as Subject.
Copyright 2006-2011
Observer
Real Life vs Java Object
Copyright 2006-2011
Real Life vs Java Object
Observable
Copyright 2006-2011
How Observer Pattern works in Real Life ?
ObserverObservable
Register/ Attach (When he wants to watch TV)
DeRegister/ DeAttach (When he wants to not Watch TV)
ObserverObservable
Notify(When someone is Watching TV)
1
2
3
public static void main(String[] args) { //Initialise Observable Television tv = new Television("Star Plus");
//Initialise Observer TelevisionViewer tViewer = new TelevisionViewer();
//Register Observer to Observable tv.addObserver(tViewer);
//Change TV Channel tv.changeChannel("STAR CRICKET");}
Copyright 2006-2011
How Observer Pattern works in Java ?
1
public void changeChannel(String channelName) { this.channelName = channelName; setChanged(); this.notifyObservers();}2
3
public void update(Observable arg0, Object arg1) {System.out.println("Channel Changed”);
}
Copyright 2006-2011
QmPeinitiative
THANK YOU
Please visit www.eclipseinclips.com | www.ancitconsulting.com
Write to us on [email protected]
