How to write events and event handlers?

Question

Any samples?
Thanks

Answer 1

You can generate your custom events and it is very easy.
You will have to extend the EventObject class in order to make an class representing the event.
Iam giving a brief eg:
class MyEvent extends EventObject
MyEvent(Object source)
super(source);//source which generated the event.
//your own code
interface MyEventListener
public void myEventPerformed(MyEvent e);
class abc
java.util.ArrayList arr;
abc
arr = new java.util.ArrayList();
public synchronized void addMyEventListener (MyEventListener l)
arr.add(l);
public synchronized void removeMyEventListener (MyEventListener l)
arr.remove(arr.indexOf(l));
protected void notifyTransEvent(Object source)
MyEvent tEvent = new MyEvent(source);
Iterator itr = arr.iterator();
Iterator itr = arr.iterator();
while(itr.hasNext())
((MyEventListener)itr.next()).myEventPerformed(tEvent);
Now anyone implementing the MyEventListener inetrface can be added in the ArrayList.The ArrayList is the list representing the interesting parties who want to receive the event.When registered they will receive the event.
This class abc is just like an component which on certain situations generate event.You can call notifyEvent in any case where you want the event to be generated.
You will then add this class to your main class as this
class xyz implements MyEventListener
abc obj;
xyz()
obj.addMyEventListener(this);
public void myEventPerformed(MyEvent e)
//your handling code
Hope this example will suffice.