How Do You Implement Java’s Observer Pattern for Event Handling?

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.