Why is EventListenerList traversed backwards in fireFooXXX()?
- by Joonas Pulakka
I don't understand the rationale of this code, taken from javax.swing.event.EventListenerList docs:
protected void fireFooXXX() {
// 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]==FooListener.class) {
// Lazily create the event:
if (fooEvent == null)
fooEvent = new FooEvent(this);
((FooListener)listeners[i+1]).fooXXX(fooEvent);
}
}
}
Why is the list traversed backwards?
Why is only every second listener called?
The event firing is implemented exactly this way in javax.swing.tree.DefaultTreeModel among others, so it's obviously me who's just not getting something.
