How Do You Implement Java’s Observer Pattern for Event Handling?
The Observer Pattern allows an object to notify other objects of state changes.
Implementation
Implement Observer and Observable to create a publish-subscribe system.
Example Code
import java.util.Observable;
import java.util.Observer;
class NewsAgency extends Observable {
void publishNews(String news) {
setChanged();
notifyObservers(news);
}
}
class NewsChannel implements Observer {
public void update(Observable o, Object arg) {
System.out.println("Breaking News: " + arg);
}
}
NewsAgency agency = new NewsAgency();
NewsChannel channel = new NewsChannel();
agency.addObserver(channel);
agency.publishNews("New Java Release!");
This example demonstrates the implementation of the Observer Pattern in Java.