Design Patterns :: Observer Pattern

Design Patterns :: Observer Pattern

In this post, we will see about the Observer Design Pattern. To know more about design patterns, visit Software Design Pattern.

Observer Design Pattern is useful in scenarios where changes to an Object is of interest to multiple parties.

Mostly used in all the GUI tool kits(e.g. Swings) and event dispatch mechanisms.

Java Code 

1. Observable 
1. The Object which is to be observed
2. Holds the reference to the list of Observers that are interested in changes happening in this object
2. Observer (Interface or Abstract class
3. Concrete Observer 1, Concrete Observer 2 ...

Observable.java

class Observable {

private List<Observer> observers = new ArrayList<Observer>();

public void addObserver(Observer o) {

}

public void removeObserver(Observer o) {

}

public void notifyObservers() {

} 
 
}