Generic widget in UiBinder

Question

I just created widget:

public class myWidget<T> extends FlowPanel {
private T value;

public T getValue()
{
    return value;
}

public myWidget(T[] values) {
    for (T value : values)
    {
        //do action
    }
}

How can I add it using UiBinder? Is it possible at all?

Answer 1

Yes you can. You have to import the package which contains the myWidget class into an XML namespace. Say your package is called com.test.widgets, the declarative layout looks like this:

<ui:UiBinder xmlns:ui='urn:ui:com.google.gwt.uibinder'
    xmlns:g='urn:import:com.google.gwt.user.client.ui'
    xmlns:my='urn:import:com.test.widgets'>

  <my:myWidget>
    <g:Label>A label</g:Label>
    <g:Label>A second label</g:Label>
  </my:myWidget>
</ui:UiBinder>

Note the import xmlns:my='urn:import:com.test.widgets' and the usage <my:myWidget>.

Answer 2

To have your widget usable in Uibinder it must implement at least IsWidget interface. Being a widget already, it of course already implements IsWidget.

Therefore, any non-widget could also be used as a child widget element in uibinder by having it implement IsWidget.

The IsWidget interface requires the non-widget to implement the method asWidget(). Therefore, such a non-widget would have to act as a widget container.

Implementing IsWidget will only allow the class to be used as a child widget element.

Let's say your class is

com.zzz.client.ui.HelloKitty

In order for it be able to have child widget elements, it must implement HasWidgets.

<ui:UiBinder
  xmlns:ui='urn:ui:com.google.gwt.uibinder'
  xmlns:g='urn:import:com.google.gwt.user.client.ui'
  xmlns:z='urn:import:com.zzz.client.ui'>

  <g:VerticalPanel>
    <z:HelloKitty>
      <g:button ..../>
      <g:textbox>asdf</g:textbox>
    </z:HelloKitty>
  <g:VerticalPanel>

</ui:UiBinder>

Or, it could also just implement HasOneWidget.

In order to allow the class to have text between its uibinder tags, it must implement HasText.

<ui:UiBinder
  xmlns:ui='urn:ui:com.google.gwt.uibinder'
  xmlns:g='urn:import:com.google.gwt.user.client.ui'
  xmlns:z='urn:import:com.zzz.client.ui'>

  <g:VerticalPanel>
    <z:HelloKitty>qwerty</z:HelloKitty>
  <g:VerticalPanel>

</ui:UiBinder>

In order to accept valid HTML between its tags, I believe you should have it implement HasHTML.