WizardDialog.open() throw NullPointerException - eclipse-plugin

Question

I am trying to add NewCSSWizard on the toolbar. For this I used Platform Command Framework, add command and handler extension points. extends WizardHandler but it doesn't work and throws NPE. If in method executeHandler(ExecutionEvent) I create own wizard - it works well.
public class NewCssWizardHandler extends WizardHandler
{
#Override
protected void executeHandler(ExecutionEvent event)
{
try
{
IWorkbenchWindow window = HandlerUtil.getActiveWorkbenchWindowChecked(event);
WizardDialog wizardDialog = new WizardDialog(window.getShell(), new NewCSSWizard());
wizardDialog.open();
}
catch (ExecutionException e)
{
e.printStackTrace();
}
}
#Override
protected String getWizardIdParameterId()
{
return IWorkbenchCommandConstants.FILE_NEW_PARM_WIZARDID;
}
#Override
protected IWizardRegistry getWizardRegistry()
{
return PlatformUI.getWorkbench().getNewWizardRegistry();
}
}
Stacktrace:
org.eclipse.e4.core.di.InjectionException: java.lang.NullPointerException
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:63)
at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:231)
at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:212)
at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:131)
at org.eclipse.e4.core.commands.internal.HandlerServiceImpl.executeHandler(HandlerServiceImpl.java:171)
at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.executeItem(HandledContributionItem.java:831)
at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.handleWidgetSelection(HandledContributionItem.java:724)
at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.access$7(HandledContributionItem.java:708)
at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem$4.handleEvent(HandledContributionItem.java:647)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1276)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3562)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3186)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1053)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:942)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
Caused by: java.lang.NullPointerException
at org.eclipse.ui.ide.IDE.computeSelectedResources(IDE.java:1480)
at org.eclipse.wst.css.ui.internal.wizard.NewCSSWizard.addPages(NewCSSWizard.java:48)
at org.eclipse.jface.wizard.WizardDialog.createContents(WizardDialog.java:605)
at org.eclipse.jface.window.Window.create(Window.java:431)
at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:1089)
at org.eclipse.jface.window.Window.open(Window.java:790)
at com.sdad.sdk.ui.actions.NewCssWizardHandler.executeHandler(NewCssWizardHandler.java:27)
at org.eclipse.ui.internal.handlers.WizardHandler.execute(WizardHandler.java:279)
at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:290)
at org.eclipse.ui.internal.handlers.E4HandlerProxy.execute(E4HandlerProxy.java:76)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:56)

Answer 1

Looks like you passed a null argument to computeSelectedResources. Just do a null check before calling that method. I'm assuming that the code you are working on is NewCSSWizard.java.

Answer 2

public class NewFileHandler extends AbstractHandler implements IHandler {
#Override
public Object execute(ExecutionEvent event) throws ExecutionException {
IWorkbenchWindow window = HandlerUtil
.getActiveWorkbenchWindowChecked(event);
System.out.println("window ok");
NewFileWizard nfw = new NewFileWizard();
nfw.init(PlatformUI.getWorkbench(), new StructuredSelection());
WizardDialog dialog = new WizardDialog(window.getShell(), nfw);
System.out.println("new WizardDialog");
dialog.open();
System.out.println("dialog open");
return null;
}
}