Creating custom events in Java

First, create the event that your application will fire

public MyEvent extends EventObject {
public static final MYEVENT_OPEN = 1;
public static final MYEVENT_CLOSE = 2;

private int type;

public MyEvent(int eventType) {
super(type);
type = eventType;
}
public int getType() {
return type;
}

}

Next, create the interface that has to be implemented by the classes that will receive your event MyEvent.

public interface MyEventListener extends java.util.EventListener {
public void myEventWasReceived(MyEvent event);
}

Then, create a controlComponent that knows what classes that are subscribing to your event MyEvent.

public abstract class MyEventControlComponent {
static EventListenerList myEventListeners = new EventListenerList();

public static addMyEventListener(MyEventListener listener) {
myEventListeners.add(MyEventListener.class, listener);
}

public static removeMyEventListener(MyEventListener listener) {
myEventListerers.remove(MyEventListener.class, listener);
}

protected void fireMyEvent(MyEvent event) {
Object[] lsteners = myEventListeners.getListenerList();
for (int i = 0; i<listeners.length; i+=2) {
if(listeners[i]==MyEventListener.class) ((MyEventListener)listeners[i+1]).myEventWasReceived(event);
}
}
}

Now, this is the framework and it is possible to start creating subscribers and notifiers of MyEvent. Each notifier has to extend the MyControlComponent. To fire a new MyEvent, just

this.fireMyEvent(new MyEvent(MyEvent.MY_EVENT_OPEN));

The subscriber's of MyEvent, has to register itself with the MyEventControlComponent, this is done by

public class MyTest implements MyEventListener {
public MyTest() {
MyEventControlComponent.addMyEventListener(this);
}

Then implement the method(s) from the MyEventListener interface, and handle the events:

public void myEventWasReceived(MyEvent event) {
//Some action based on the event, and its information
}