Question

I have the following code:

public class A extends Composite {
    public String url;
    public String result;
    public A(String url, String result) {
         this.url = url;
         this.result = result;
    }



 public A someObject;
 public VerticalPanel vp = new VerticalPanel();
 public void init() {
    someObject = new A(url, result);
    someObject.setStyleName("style");
    this.vp.add(someObject);
}

But when I call ‘this.vp.add(…)’ it says:

  (TypeError): Cannot read property '__gwt_resolve' of null

How can that be??

Answer 1

Your Composite widget is missing a call to initWidget(). If it were a Widget it would probably be missing a call to setElement().

See https://developers.google.com/web-toolkit/doc/latest/DevGuideUiCustomWidgets