Re: Destroy a widget

[Benjamin Possolo]

I presume by uibinder owner you mean your HelloWorld class overrides the onEvent() method, is that correct?

I also presume that you have some other component that is using the HelloWorld objects and attaching them to the view.

For example, in your EntryPoint:

HelloWorld h1 = new HelloWorld();

HelloWorld h2 = new HelloWorld();

FlowPanel panel = new FlowPanel();

panel.add(h1);

panel.add(h2);

GWT.getRoot().add(panel);

If you want to "destroy" h1, and have it stop reacting to events, simply remove it from the dom and ensure it is garbage collected (ie. set your reference to null):

panel.remove(h1);

h1 = null;

[Benjamin Possolo]

Sorry there is a typo there.

GWT.getRoot().add(panel);

should be

RootPanel.get().add(panel);

[Jens]

When you create two HelloWorld widgets each of them receives its own events. If you use @UiHandler in your UiBinder widget and you want to stop receive events for a widget without removing the widget itself from the parent (for whatever reason) you have to "disable" your @UiHandler implementation.

So you would end up having

@UiHandler(...)

void onEvent(...) {

  if(handleEvents) {

     //do your event logic

  }

}

or you use a Delegate interface that a class can implement and that contains your event logic implementation:

@UiHandler(...)

void onEvent(...) {

  if(delegate != null) {

     delegate.onEvent();

  }

}

In that case you would disable your events by nulling your delegate: widget.setDelegate(null)

Otherwise you have to remove the widget from the parent.

-- J.

[Jose María Zaragoza]

If you want to "destroy" h1, and have it stop reacting to events, simply remove it from the dom and ensure it is garbage collected (ie. set your reference to null):

panel.remove(h1);

h1 = null;

Thanks

Garbage collected? I thought that we were in a Javascript world

Setting to null doesn't work like I want because it's Javascript code.

And I don't want to remove it from a panel , but "destroy it" as entity. Maybe that doesn't have any sense, because I don't know how is implemented by GWT compiler into Javascript code, but  h1=null doesn`t work for me

[Jose María Zaragoza]

Thanks for you answer. 

But  "to remove the widget from the parent." doesn`t avoid to receive events ( or my tests were wrong )

[Benjamin Possolo]

I can't really understand what you are asking or saying.

If you want the widget to remain visible but to stop receiving events, do what Jens said: suppress the event handling logic in the event handler.

If you want the widget to stop being visible and to stop receiving events, just do what I said: remove the widget from it's container.

and yes, javascript also has garbage collection otherwise every web application would be one giant memory leak