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Jeffrey Spoon · Guest

Hello, I'm trying to figure out AWT custom events.

I saw the code below in googlegroups.

My question is, what class should AClass represent? I'm not sure what
class to pass here and I don't understand what obj is passed when firing
your event (in the doSomething method).

Cheers

<http://groups.google.com/group/comp.lang.java.help/browse_frm/thread/7e6
b6a6c9e100e93/d4492375361b6d0a?lnk=st&q=java+custom+events+and+listeners&
rnum=1#d4492375361b6d0a>

----- First, create an interface that all your event listeners should
implement.

import java.util.EventListener;
public interface YourListener extends EventListener
{
public void yourMethod1(YourEvent evt);
public void yourMethod2(YourEvent evt);

}

------ Then, create YourEvent class :

import java.awt.AWTEvent;
public class YourEvent extends AWTEvent {

public YourEvent(AClass obj)

super(obj, YOUR_EVENT);
}
// Give your event a unique eventID
public static final int YOUR_EVENT = java.awt.AWTEvent.RESERVED_ID_MAX
+
1234;

}

------ Next, in the class where you want to fire the custom events.
Add
the following lines:

import javax.swing.event.EventListenerList;
public class YourCustomEventGeneratorClass
{
...
private EventListenerList listenerList = new EventListenerList();;
private YourEvent yourEvent = null;
...

public void doSomething()
{ ...
fireYourEvent(obj);
...
}

/** Adds a event listener to this object */
public void addYourListener(YourListener l)
{
listenerList.add(YourListener.class, l);
}

/** Removes a event listener from this object */
public void removeYourListener(YourListener l)
{
listenerList.remove(YourListener.class, l);
}

/** Notify all listeners that have registered interest for notification
when an
object gets.
*/
protected void fireYourEvent(AClass obj)
{
// Guaranteed to return a non-null array
Object[] listeners = listenerList.getListenerList();
// Process the listeners last to first, notifying
// those that are interested in this event
for (int i = listeners.length-2; i>=0; i-=2)
{
if (listeners[i]==YourListener.class)
{
// Lazily create the event:
if (yourEvent == null)
yourEvent = new YourEvent(obj);
((YourListener)listeners[i+1]).yourMethod1(yourEvent);
}
}
} // end fire

} // end class

------ Finally, implement the interface in any class you want.

public class YourEventTargetClass implements YourListener
{
...
private YourCustomEventGeneratorClass yourClass = new
YourCustomEventGeneratorClass();
yourClass.addYourListener(this);
...
public void yourMethod1(YourEvent evt)
{
// Add your implementation here
}
public void yourMethod2(YourEvent evt)
{
// Add your implementation here
}

}

--
Jeffrey Spoon

Roedy Green · Guest

On Sun, 20 Nov 2005 15:09:24 +0000, Jeffrey Spoon
<JeffreySpoon (AT) hotmail (DOT) com> wrote, quoted or indirectly quoted someone
who said :

Jeffrey Spoon · Guest

In message <43809e58$0$1456$ed2619ec (AT) ptn-nntp-reader01 (DOT) plus.net>, Thomas
Hawtin <usenet (AT) tackline (DOT) plus.com> writes

Jeffrey Spoon · Guest

In message <4380b85f$0$1466$ed2619ec (AT) ptn-nntp-reader01 (DOT) plus.net>, Thomas
Hawtin <usenet (AT) tackline (DOT) plus.com> writes