NullPointerException in DefaultHelpUi.displayContext

[2wendex2]

In ua/org.eclipse.help.ui/src/org/eclipse/help/ui/internal/DefaultHelpUI.java, lines 330-336:

if (adapter != null)
	context = adapter.getContext(c);
String contextText = context.getText();

But javadoc of IContextProvider.getContext(Object) says:

return context help for the provided target or null if none is defined.

I.e. adapter.getContext(c) may return null then we call context.getText() and give NullPointerException.

[jukzi]

If you have an actual NPE please quote the whole stacktrace and give a reproducer. Or are you just speculating that there is a possible NPE?

[2wendex2]

@jukzi I have an actual NPE. Stack trace:

!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException: Cannot invoke "org.eclipse.help.IContext.getText()" because "context" is null
	at org.eclipse.help.ui.internal.DefaultHelpUI.displayContext(DefaultHelpUI.java:336)
	at org.eclipse.help.ui.internal.DefaultHelpUI.displayContext(DefaultHelpUI.java:305)
	at org.eclipse.ui.internal.help.WorkbenchHelpSystem.displayContext(WorkbenchHelpSystem.java:750)
	at org.eclipse.ui.internal.help.WorkbenchHelpSystem$WorkbenchHelpListener.helpRequested(WorkbenchHelpSystem.java:133)
	at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:157)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4273)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1066)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4071)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3659)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1155)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:342)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1046)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:648)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:342)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:555)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:173)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:208)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:136)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:402)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:651)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:588)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1459)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1432)

To reproduce this you should a create your custom IContextProvider, in get context write return null and press F1.

[jukzi]

good, can you provide a fix, please?