Design patterns - Observer Pattern
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The document discusses the observer pattern, which allows objects called observers to monitor observable objects. In real life, a person is an observer of a TV as the observable object. In Java, observable objects are called subjects and can notify registered observer objects of changes. The observer pattern works by observers registering with observables, then observables notifying observers of changes.
![How Observer Pattern works in Java ?
public void changeChannel(String channelName) {
public static void main(String[] args) { this.channelName = channelName;
//Initialise Observable setChanged();
Television tv = new Television("Star Plus"); this.notifyObservers();
}
2
//Initialise Observer
TelevisionViewer tViewer = new TelevisionViewer();
//Register Observer to Observable 3
1 tv.addObserver(tViewer);
//Change TV Channel
tv.changeChannel("STAR CRICKET");
} public void update(Observable arg0, Object arg1) {
System.out.println("Channel Changed”);
}
Copyright 2006-2011](https://image.slidesharecdn.com/designpatterns-observerpattern-120323022941-phpapp01/85/Design-patterns-Observer-Pattern-7-320.jpg)
Design patterns - Observer Pattern
- 1. QmPe initiative OBSERVER PATTERN explained ! Prepared by Annamalai C Copyright 2006-2011
- 2. 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 Observable Observer Copyright 2006-2011
- 3. Observer Pattern in Java Observable Objects are called as Subject. Copyright 2006-2011
- 4. Real Life vs Java Object Observer Copyright 2006-2011
- 5. Real Life vs Java Object Observable Copyright 2006-2011
- 6. How Observer Pattern works in Real Life ? 1 Register/ Attach (When he wants to watch TV) DeRegister/ DeAttach (When he wants to not Watch TV) Observable Observer 2 Notify (When someone is Watching TV) 3 Observable Observer Copyright 2006-2011
- 7. How Observer Pattern works in Java ? public void changeChannel(String channelName) { public static void main(String[] args) { this.channelName = channelName; //Initialise Observable setChanged(); Television tv = new Television("Star Plus"); this.notifyObservers(); } 2 //Initialise Observer TelevisionViewer tViewer = new TelevisionViewer(); //Register Observer to Observable 3 1 tv.addObserver(tViewer); //Change TV Channel tv.changeChannel("STAR CRICKET"); } public void update(Observable arg0, Object arg1) { System.out.println("Channel Changed”); } Copyright 2006-2011
- 8. THANK YOU Please visit www.eclipseinclips.com | www.ancitconsulting.com Write to us on info@ancitconsulting.com QmPe initiative Copyright 2006-2011