stackoom
  简体   繁体   中英

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

 原文  2011-09-26 05:14:00  4   1    java/ gwt

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:snehitp@cs.columbia.edu\">snehitp@cs.columbia.edu</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)

1 answers

solution1
 1 ACCPTED  2011-09-26 07:35:08

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.

暂无
暂无

The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.

Related Question how to dynamically add swt widgets to a composite? How does composite object communicate with parent object? How to add a widget from the mac_widgets java api to HudWindow How to add a composite to another composite? How to implement a composite pattern in Java? How to implement SelectionEvent in Composite GWT How to add a list of TextBox widgets to a Panel widget declared using UiBinder (GWT)? How can I do a JPA @OneToMany unidirectional mapping with the parent entity's composite key? how to remove a child composite from parent composite in swt? How to disable all widgets inside Panel or inside Composite?
Related Tags
 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM