Creating a Listener

Question

How do i go about creating my own customized listener classes? Like for example, i want to create a SocketListener to manage socket's properties (similiar to Winsock in VB) using events.

Answer 1

Take a look at how the AWT event listeners are implemented, it really simple:
First, make an interface having method declarations of those 'messages' you want your listener to receive.
Like eg. public interface SocketListener {
public void socketEvent1();
}Then, in your 'listener-server' i.e. you socket class, you add (at least) public class MySocket {
private Collection listeners = new List();
public void addListener(SocketListener listener) {
   listeners.add(listener);
} Whenever you want to send a message/notification, simply iterate through all listeners and call the event method//...
Iterator itListener = listeners.iterator();
while (itListener.hasNext())
   ((SocketListener)itListener.next()).socketEvent1();
//...Of course, it should be possible to remove a listener and you can also add return values as well as arguments to the methods.
Now, all the classes interrested in 'listening' to your Socket class, should implement the SocketListener interface and add themself to the Socket class...
This should do the trick :-)