I sitll cant work out from the code in this article, how to fire an
event:
final ListBox dropBox = new ListBox(false);
dropBox.addItem("");
dropBox.addItem("a");
dropBox.addItem("b");
dropBox.addItem("c");
dropBox.addItem("d");
dropBox.addChangeHandler(new ChangeHandler()
{
// @Override
public void onChange(ChangeEvent event)
{
switch (dropBox.getSelectedIndex()) {
case 0:
ApptPrice.setText("");
break;
case 1:
ApptPrice.setText("8.50");
break;
case 2:
ApptPrice.setText("9.50");
break;
case 3:
ApptPrice.setText("10.50");
break;
case 4:
ApptPrice.setText("11.50");
break;
default:
ApptPrice.setText("should never see
this");
break;
}
}
});
dropBox.setItemSelected(setitemtoselect, true);
dropBox.fireEvent(onChange);
Its this last line I want to implement, Im setting the selection
programattically (based on selections elsewhere in the code) and i
need to fire the onChange event because as stated in the javadoc:
"Note that setting the selection programmatically does not cause the
ChangeHandler.onChange(ChangeEvent) event to be fired. "
On Aug 20, 5:45 pm, jscheller <[email protected]> wrote:
> Thanks Thomas... That and gazing wisely (or at least trying to give
> the appearance of looking somewhat informed) at TextBoxBase.class got
> me this...
>
> public class MyComposite extends Composite implements
> HasValueChangeHandlers<String> {
>
> private void internalMethodToHandleUpdates() {
> // handle validation and all sorts of other stuff, then
> if
> // if it looks good let outsiders know...
>
> ValueChangeEvent.fire( this, "theNewValue" );
> }
>
> public HandlerRegistration addValueChangeHandler(ValueChangeHandler
> handler) {
> return addHandler(handler, ValueChangeEvent.getType());
> }
>
> }
>
> ..which looks like it should work. Still fuzzy on why the widget can't
> manage an independent list of handlers under the hood, and the event
> typing system still has me baffled, but this'll get me past the puzzle
> box that kept me busy yesterday and seems less complex than what I was
> doing... Thanks for your help!
>
> On Aug 20, 2:25 am, Thomas Broyer <[email protected]> wrote:
>
> > On Aug 20, 2:33 am, jscheller <[email protected]> wrote:
>
> > > Hello -
>
> > > So, I've got a composite that has something like this inside it...
>
> > > private HandlerManager changeHandlers = new HandlerManager( null );
>
> > > public HandlerRegistration addValueChangeHandler(ValueChangeHandler
> > > handler)
> > > { return changeHandlers.addHandler(ValueChangeEvent.getType(),
> > > handler); }
>
> > You shouldn't ever instantiate a HandlerManager (except if you use one
> > as an "event bus"; but that's another story and at least this rule is
> > true for widgets); just call the Widget#addHandler(...) method.
>
> > public HandlerRegistration addValueChangeHandler
> > (ValueChangeHandler<String> handler) {
> > return addHandler(handler, ValueChangeEvent.getType());
>
> > }
> > > ...and somewhere down the pipeline, I want to actually fire off an
> > > event to anyone who registered a handler when the composite decides
> > > it's represented value has changed and wants the rest of the world to
> > > know. However, the syntax for actually constructing and firing the
> > > event off has got me pulling my hair out.
>
> > > I've tried variants of sending the event through the change
> > > handlers...
>
> > > changeHandlers.fireEvent( new ValueChangeEvent("foo") );
> > > changeHandlers.fireEvent( new ValueChangeEvent<String>("foo") );
>
> > > ...and using the static fire() method in the event class itself...
>
> > > ValueChangeEvent<String>.fire( changeHandlers, "foo");
>
> > > ...and Eclipse complains loudly about all of these constructions. I
> > > mean, I know this can't be that hard, but I can't find any good
> > > examples of things like this using the new (GWT 1.6 or later) event
> > > handlers, and reading the code sends me down a DOM event/Java generics
> > > rabbit hole that I'm frankly not experienced enough to deal with
> > > yet...
>
> > > Any help appreciated!
>
> > ValueChangeEvent.fire(this, "foo");
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