LazyPanel in GWT (Uibinder) - gwt

Question

I want to learn the utility of lazypanel of GWT. I want to use it using Uibinder. I have written the code as below. I want to use the lazy panel for tablayoutpanel.
XML file
<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
<ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder"
xmlns:g="urn:import:com.google.gwt.user.client.ui" xmlns:d="urn:import:com.google.gwt.dom.client"
xmlns:lazy="urn:import:abc.client">
<g:HTMLPanel>
<lazy:Lazy1></lazy:Lazy1>
</g:HTMLPanel>
</ui:UiBinder>
This is the java file associated.
Lazy1.java
package abc.client;
import com.google.gwt.user.client.ui.Label;
import com.google.gwt.user.client.ui.LazyPanel;
import com.google.gwt.user.client.ui.Widget;
public class Lazy1 extends LazyPanel{
Label label = new Label("Mani");
#Override
protected Widget createWidget() {
return label;
}
}
I am getting the exceptions and error as below:-
13:00:08.222 [ERROR] [abc] Generator 'com.google.gwt.uibinder.rebind.UiBinderGenerator' threw an exception while rebinding 'abc.client.AbcUI.abcUIUiBinder'
java.lang.NullPointerException: null
at com.google.gwt.uibinder.elementparsers.LazyPanelParser.parse(LazyPanelParser.java:40)
at com.google.gwt.uibinder.rebind.UiBinderWriter.parseElementToField(UiBinderWriter.java:934)
at com.google.gwt.uibinder.elementparsers.WidgetInterpreter.interpretElement(WidgetInterpreter.java:88)
at com.google.gwt.uibinder.elementparsers.WidgetInterpreter.interpretElement(WidgetInterpreter.java:34)
at com.google.gwt.uibinder.elementparsers.InterpreterPipe.interpretElement(InterpreterPipe.java:58)
at com.google.gwt.uibinder.rebind.GetInnerHtmlVisitor.visitElement(GetInnerHtmlVisitor.java:45)
at com.google.gwt.uibinder.rebind.ChildWalker.accept(ChildWalker.java:48)
at com.google.gwt.uibinder.rebind.GetInnerHtmlVisitor.getEscapedInnerHtml(GetInnerHtmlVisitor.java:33)
at com.google.gwt.uibinder.rebind.XMLElement.consumeInnerHtml(XMLElement.java:391)
at com.google.gwt.uibinder.rebind.XMLElement.consumeInnerHtml(XMLElement.java:403)
at com.google.gwt.uibinder.elementparsers.HTMLPanelParser.parse(HTMLPanelParser.java:57)
at com.google.gwt.uibinder.rebind.UiBinderWriter.parseElementToField(UiBinderWriter.java:934)
at com.google.gwt.uibinder.rebind.UiBinderParser.parse(UiBinderParser.java:146)
at com.google.gwt.uibinder.rebind.UiBinderWriter.parseDocumentElement(UiBinderWriter.java:1368)
at com.google.gwt.uibinder.rebind.UiBinderWriter.parseDocument(UiBinderWriter.java:1073)
at com.google.gwt.uibinder.rebind.UiBinderGenerator.generateOnce(UiBinderGenerator.java:177)
at com.google.gwt.uibinder.rebind.UiBinderGenerator.generate(UiBinderGenerator.java:129)
at com.google.gwt.core.ext.IncrementalGenerator.generateNonIncrementally(IncrementalGenerator.java:40)
at com.google.gwt.dev.javac.StandardGeneratorContext.runGeneratorIncrementally(StandardGeneratorContext.java:657)
at com.google.gwt.dev.cfg.RuleGenerateWith.realize(RuleGenerateWith.java:41)
at com.google.gwt.dev.shell.StandardRebindOracle$Rebinder.rebind(StandardRebindOracle.java:79)
at com.google.gwt.dev.shell.StandardRebindOracle.rebind(StandardRebindOracle.java:276)
at com.google.gwt.dev.shell.ShellModuleSpaceHost.rebind(ShellModuleSpaceHost.java:141)
at com.google.gwt.dev.shell.ModuleSpace.rebind(ModuleSpace.java:595)
at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:465)
at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)
at com.google.gwt.core.shared.GWT.create(GWT.java:57)
at com.google.gwt.core.client.GWT.create(GWT.java:85)
at abc.client.AbcUI.<clinit>(AbcUI.java:12)
at abc.client.ABC.onModuleLoad(ABC.java:10)
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.ModuleSpace.onLoad(ModuleSpace.java:406)
at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:200)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:526)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
at java.lang.Thread.run(Thread.java:662)
ABC.java
package abc.client;
import com.google.gwt.core.client.EntryPoint;
import com.google.gwt.user.client.ui.RootPanel;
public class ABC implements EntryPoint {
public void onModuleLoad() {
RootPanel.get().add(new AbcUI());
}
}
AbcUi.java
package abc.client;
import com.google.gwt.core.client.GWT;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HTMLPanel;
import com.google.gwt.user.client.ui.LazyPanel;
public class AbcUI extends Composite {
interface abcUIUiBinder extends UiBinder<HTMLPanel, AbcUI> {}
private static abcUIUiBinder uiBinder = GWT.create(abcUIUiBinder.class);
public AbcUI() {
initWidget(uiBinder.createAndBindUi(this));
}
}

Answer 1

According to this you have this error if you do not have an #UiField annotation for the LazyPanel. So I would try the following:
For the UiBinder XML file:
<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
<ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder"
xmlns:g="urn:import:com.google.gwt.user.client.ui"
xmlns:d="urn:import:com.google.gwt.dom.client"
xmlns:lazy="urn:import:abc.client">
<g:HTMLPanel>
<lazy:Lazy1 ui:field="myLazy1"/>
</g:HTMLPanel>
</ui:UiBinder>
For your AbcUi.java file:
package abc.client;
import com.google.gwt.core.client.GWT;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HTMLPanel;
import com.google.gwt.user.client.ui.LazyPanel;
public class AbcUI extends Composite {
interface abcUIUiBinder extends UiBinder<HTMLPanel, AbcUI> {}
private static abcUIUiBinder uiBinder = GWT.create(abcUIUiBinder.class);
#UiField
Lazy1 myLazy1;
public AbcUI() {
initWidget(uiBinder.createAndBindUi(this));
}
}