How to add composite widgets: This widget's parent does not implement HasWidgets

Question

I keep getting thrown an error: "This widget's parent does not implement HasWidgets. Of combed the web (including stackoverflow), but can't figure out what's the problem. I know its a problem with the way I add the Download object to the VerticalPanel 'text', however, I don't know why its throwing it, or how to fix it. Furthermore, when I run the application it first succeeds and only throws the error the second time around I try to access the download page. Any help would be greatly appreciated!

public class SIXPAC implements EntryPoint, HasWidgets
{
    private VerticalPanel mainPanel = new VerticalPanel() ;
    private HorizontalPanel menu = new HorizontalPanel() ;
    private VerticalPanel text = new VerticalPanel() ;
    private SIXPACServiceAsync services = GWT.create( SIXPACService.class ) ;

    public void onModuleLoad() 
    {
        header() ;
        changePage( "about.txt" ) ;
        footer() ;

        RootPanel.get( "sixPac" ).add( mainPanel ) ;
        mainPanel.setWidth("100%");
    }

    public void header()
    {
        menu.add( menu stuff... ) ;
        mainPanel.add( menu ) ;
        mainPanel.add( text ) ;
    }

    public void footer()
    {
        mainPanel.add( footer stuff... ) ;
    }

    public void changePage( String token )
    {
            if( token.equals( "download.txt" ) )        // else its download page and need to set up the forms
        {
            text.clear() ;
            try
            {
                add( new Download() ) ;
            }
            catch( Exception e )
            {
                System.out.println( e ) ;
            }
            text.setStyleName( "contentbox" ) ;
        }
    }

    public void add(Widget w) // tried basic implementation of the HasWidgets methods...
    {
        text.add( w ) ;
    }

    public void clear() 
    {

    }

    public Iterator<Widget> iterator() {
        // TODO Auto-generated method stub
        return null;
    }

    public boolean remove(Widget w) {
        // TODO Auto-generated method stub
        return false;
    }
}

For the download class I basically removed everything for the sake of testing:

package com.sixpac.website.client;

import java.util.Iterator;

public class Download extends Composite
{
    private static VerticalPanel verticalPanel = new VerticalPanel();

    public Download() 
    {
        verticalPanel.setStyleName("contentbox");
        initWidget( verticalPanel );
        verticalPanel.setWidth("100%");

        verticalPanel.add( new HTML( "<h1>Download</h1>" ) ) ;

        HorizontalPanel horizontalPanel = new HorizontalPanel();
        horizontalPanel.setHorizontalAlignment(HasHorizontalAlignment.ALIGN_CENTER);
        horizontalPanel.setWidth("100%");
        verticalPanel.add( horizontalPanel ) ;

        System.out.println( "creating new login" ) ;
        Login login = new Login() ;
        System.out.println( "creating new register" ) ;
        Register register = new Register() ;

        horizontalPanel.add( login ) ;
        login.setSize("75%", "310px");
        horizontalPanel.setCellVerticalAlignment(login, HasVerticalAlignment.ALIGN_BOTTOM);
        horizontalPanel.add( register ) ;
        register.setSize("90%", "257px");
        horizontalPanel.setCellVerticalAlignment(register, HasVerticalAlignment.ALIGN_BOTTOM);
        setStyleName("gwt");
    }

    public static void downloadOk()
    {
        verticalPanel.add( new HTML( "<br/><br/>" ) ) ;
        verticalPanel.add( new HTML( "<div class=\"contentbox downloadok\">\n\t\n<p>Thank you for downloading SIXPAC Version 0.5 (Beta).</p>\n<p>Please direct all technical questions and bug-reports to Snehit Prabhu (<a href=\"mailto:[email protected]\">[email protected]</a>)</p>\n\t\n<br />\n\t\n<a href=\"#\" class=\"downloadbutton\">Download SIXPAC</a>\n\n<br /><br />\n</div>\n\n\n</div><!--contentbox-->" ) ) ;
    }
}

The stack trace:

    02:24:14.763 [ERROR] [sixpac] Uncaught exception escaped

com.google.gwt.event.shared.UmbrellaException: One or more exceptions caught, see full set in UmbrellaException#getCauses
    at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:129)
    at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
    at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
    at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
    at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:698)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid(ModuleSpace.java:289)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid(JavaScriptHost.java:107)
    at com.google.gwt.dom.client.DOMImplStandard.dispatchEvent(DOMImplStandard.java)
    at com.google.gwt.dom.client.Element$.dispatchEvent$(Element.java:142)
    at com.google.gwt.user.client.ui.CustomButton.onClick(CustomButton.java:825)
    at com.google.gwt.user.client.ui.PushButton.onClick(PushButton.java:190)
    at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:656)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
    at java.lang.Thread.run(Thread.java:680)
Caused by: java.lang.AssertionError: This UIObject's element is not set; you may be missing a call to either Composite.initWidget() or UIObject.setElement()
    at com.google.gwt.user.client.ui.UIObject.getElement(UIObject.java:527)
    at com.google.gwt.user.client.ui.ComplexPanel.add(ComplexPanel.java:94)
    at com.google.gwt.user.client.ui.VerticalPanel.add(VerticalPanel.java:48)
    at com.sixpac.website.client.SIXPAC.changePage(SIXPAC.java:140)
    at com.sixpac.website.client.SIXPAC$3.onClick(SIXPAC.java:69)
    at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:54)
    at com.google.gwt.event.dom.client.ClickEvent.dispatch(ClickEvent.java:1)
    at com.google.gwt.event.shared.GwtEvent.dispatch(GwtEvent.java:1)
    at com.google.web.bindery.event.shared.EventBus.dispatchEvent(EventBus.java:40)
    at com.google.web.bindery.event.shared.SimpleEventBus.doFire(SimpleEventBus.java:193)
    at com.google.web.bindery.event.shared.SimpleEventBus.fireEvent(SimpleEventBus.java:88)
    at com.google.gwt.event.shared.HandlerManager.fireEvent(HandlerManager.java:127)
    at com.google.gwt.user.client.ui.Widget.fireEvent(Widget.java:129)
    at com.google.gwt.event.dom.client.DomEvent.fireNativeEvent(DomEvent.java:116)
    at com.google.gwt.user.client.ui.Widget.onBrowserEvent(Widget.java:177)
    at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:698)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeVoid(ModuleSpace.java:289)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeVoid(JavaScriptHost.java:107)
    at com.google.gwt.dom.client.DOMImplStandard.dispatchEvent(DOMImplStandard.java)
    at com.google.gwt.dom.client.Element$.dispatchEvent$(Element.java:142)
    at com.google.gwt.user.client.ui.CustomButton.onClick(CustomButton.java:825)
    at com.google.gwt.user.client.ui.PushButton.onClick(PushButton.java:190)
    at com.google.gwt.user.client.ui.CustomButton.onBrowserEvent(CustomButton.java:656)
    at com.google.gwt.user.client.DOM.dispatchEventImpl(DOM.java:1351)
    at com.google.gwt.user.client.DOM.dispatchEvent(DOM.java:1307)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessagesWhileWaitingForReturn(BrowserChannelServer.java:337)
    at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:218)
    at com.google.gwt.dev.shell.ModuleSpaceOOPHM.doInvoke(ModuleSpaceOOPHM.java:136)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNative(ModuleSpace.java:561)
    at com.google.gwt.dev.shell.ModuleSpace.invokeNativeObject(ModuleSpace.java:269)
    at com.google.gwt.dev.shell.JavaScriptHost.invokeNativeObject(JavaScriptHost.java:91)
    at com.google.gwt.core.client.impl.Impl.apply(Impl.java)
    at com.google.gwt.core.client.impl.Impl.entry0(Impl.java:213)
    at sun.reflect.GeneratedMethodAccessor24.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at com.google.gwt.dev.shell.MethodAdaptor.invoke(MethodAdaptor.java:103)
    at com.google.gwt.dev.shell.MethodDispatch.invoke(MethodDispatch.java:71)
    at com.google.gwt.dev.shell.OophmSessionHandler.invoke(OophmSessionHandler.java:172)
    at com.google.gwt.dev.shell.BrowserChannelServer.reactToMessages(BrowserChannelServer.java:292)
    at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:546)
    at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:363)
    at java.lang.Thread.run(Thread.java:680)

Could you please post the skeleton of the Download class? It would be helpful if you post the complete stack trace too. — Behrang Saeedzadeh
– Behrang Saeedzadeh, Commented Sep 26, 2011 at 5:20
And also post the stack trace of the exception you are getting — awmross
– awmross, Commented Sep 26, 2011 at 5:22
Stack trace points to download class line 23, i thnk you need not to simplfy your code — pistolPanties
– pistolPanties, Commented Sep 26, 2011 at 6:18
For the purposes of testing I literally commented out everything in the download class. It now just has an empty constructor, and that's it. — ElfsЯUs
– ElfsЯUs, Commented Sep 26, 2011 at 6:22
For the sake of testing I have just simplified Download to: public class Download extends Composite { public download() {} } And I still get the same error... — ElfsЯUs
– ElfsЯUs, Commented Sep 26, 2011 at 6:28

pistolPanties · Accepted Answer · 2011-09-26 07:35:08Z

1

The problem is verticalPanel being static in download class. I assume that causes your code to initWidget with a bad reference when called more than once. Try removing static it should work. Also on a different note, you can implement the rest of the haswidget interface methods just like you implemented add ,by passing it through to text instance.

answered Sep 26, 2011 at 7:35

pistolPanties

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ElfsЯUs Over a year ago

Ah... thanks that worked! So in the download object I have two other objects added, Login and Register, which are both forms. For the Login once the user fills in their details and hits the login botton the Download object (or the SIXPAC botton, then has to generate an additional data box with a link. How would I send the data back down that the user has login and its ok to show him the link?

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