| FocusListenerCollection used to correctly hook up listeners which
need to listen to events from another source.
For example,
Composite widgets often need to listen to events
generated on their wrapped widget. Upon the firing of a wrapped widget's
event, the composite widget must fire its own listeners with itself as the
source of the event. To use a
DelegatingFocusListenerCollection ,
simply use the
DelegatingFocusListenerCollection instead of a
FocusListenerCollection . For example, in
SuggestBox , the
following code is used to listen to focus events on the
SuggestBox 's
underlying widget.
public void addFocusListener(FocusListener listener) {
if (focusListeners == null) {
focusListeners = new DelegatingFocusListenerCollection(this, box);
}
focusListeners.add(listener);
}
|