CODEWITHSUNDEEP
gwt
udeleng
udeleng

Reputation: 866

Click Handler working on widget but NOT on Element

I am creating an Anchor as follows:

Anchor a = new Anchor( "Click Me" );

Then I add a click handler:

a.addClickHandler( new ClickHandler() {
    @Override
    public void onClick(ClickEvent event) {
        GWT.log("Anchor Clicked");
    }
} );

I want to add the Anchor to a LI element. Since I don't have any Widgets for UL and LI, I use the following construct:

public class ElementPanel extends ComplexPanel {

    public ElementPanel(String tagName) {
        setElement(DOM.createElement(tagName));
    }

    @Override
    public void add(Widget w) {
        add(w, getElement());
    }
}

I create my UL element:

ElementPanel ul = new ElementPanel(UListElement.TAG);

I create a LI element:

ElementPanel li = new ElementPanel(LIElement.TAG);

I add my Anchor to LI, then I add LI to UL (after which I add to the document):

li.add(a);
ul.add(li);

This works fine. If instead I change the previous lines as follows, I don't see a log message:

li.getElement().appendChild(a.getElement());
ul.add(li);

Similarly, if instead I try this, I also do not see a message:

li.add(a);
ul.getElement().appendChild(li.getElement());

Previously, I had the UL element in the UIBinder. But since I was not successful in adding a click handler to an Element, I have to resort to the above approach.

Upvotes: 0

Views: 2000

Answers (1)

Thomas Broyer
Thomas Broyer

Reputation: 64561

This is how events are handled in GWT: the widget needs to be attached, and that generally means adding it to a container chain up to a RootPanel. See https://code.google.com/p/google-web-toolkit/wiki/DomEventsAndMemoryLeaks#GWT's_Solution for the details.

The easiest way to have <ul><li> if your structure doesn't change dynamically is to use an HTMLPanel (and it's even easier with UiBinder).

If the structure is dynamic, then possibly make a ComplexPanel whose root element is a UListElement and which wraps all child widgets into a LIElement. Have a look at the internals of ComplexPanel, you'll see that it attaches and detaches the child widgets whenever they are added/removed while the panel itself is attached, or whenever the panel is attached / detached.

Upvotes: 1

Related Questions