Exception when i try to open a class file inside the Jar File Viewer

[c-koell]

We are using eclipse 2024-06.

If i open a external jar file with eclipse it is opening it with the JAR File Viewer

If i try to open a class file inside i get following exception

[jpstotz]

What OS is Eclipse running on?
How is the Jar integrated into your Eclipse project? What type of Eclipse project is it located in (Java, Java Plugin, Nature Maven/Gradle, ...)?

Posting the stack trace as screenshot is a bit cumbersome as I can not copy it into my Eclipse Stacktrace console - therefore please post stacktraces never as screenshot.

[c-koell]

Eclipse is running on Windows 10.

I droped the Jar file from the file explorer directly into Eclipse.

Sorry for the Stacktrace Screenshot ;-)...

Here it is ...

java.lang.NullPointerException: Cannot invoke "org.eclipse.core.runtime.IPath.toOSString()" because the return value of "org.eclipse.core.resources.IResource.getLocation()" is null
	at org.sf.feeling.decompiler.util.UIUtil.getPathLocation(UIUtil.java:321)
	at org.sf.feeling.decompiler.editor.JavaDecompilerClassFileEditor.doSetInput(JavaDecompilerClassFileEditor.java:316)
	at org.eclipse.ui.texteditor.AbstractTextEditor.lambda$1(AbstractTextEditor.java:3171)
	at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:434)
	at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:354)
	at org.eclipse.ui.internal.WorkbenchWindow.lambda$7(WorkbenchWindow.java:2335)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:67)
	at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2332)
	at org.eclipse.ui.texteditor.AbstractTextEditor.internalInit(AbstractTextEditor.java:3188)
	at org.eclipse.ui.texteditor.AbstractTextEditor.init(AbstractTextEditor.java:3213)
	at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.lambda$0(ClassFileEditor.java:656)
	at org.eclipse.jdt.core.JavaCore.lambda$0(JavaCore.java:6146)
	at org.eclipse.jdt.internal.core.JavaModelManager.cacheZipFiles(JavaModelManager.java:5765)
	at org.eclipse.jdt.internal.core.JavaModelManager.callReadOnly(JavaModelManager.java:5754)
	at org.eclipse.jdt.core.JavaCore.callReadOnly(JavaCore.java:6130)
	at org.eclipse.jdt.core.JavaCore.runReadOnly(JavaCore.java:6145)
	at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.init(ClassFileEditor.java:656)
	at org.eclipse.ui.internal.EditorReference.initialize(EditorReference.java:353)
	at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.create(CompatibilityPart.java:344)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:586)
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:58)
	at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:977)
	at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:939)
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalInject(InjectorImpl.java:139)
	at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:386)
	at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:312)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:203)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.createFromBundle(ReflectionContributionFactory.java:90)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.doCreate(ReflectionContributionFactory.java:59)
	at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.create(ReflectionContributionFactory.java:42)
	at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.createWidget(ContributedPartRenderer.java:132)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createWidget(PartRenderingEngine.java:991)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:658)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:762)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$2.run(PartRenderingEngine.java:727)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:711)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.lambda$0(PartServiceImpl.java:105)
	at org.eclipse.e4.ui.services.internal.events.UIEventHandler.lambda$0(UIEventHandler.java:38)
	at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:183)
	at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:133)
	at org.eclipse.swt.widgets.Display.syncExec(Display.java:4814)
	at org.eclipse.e4.ui.workbench.swt.DisplayUISynchronize.syncExec(DisplayUISynchronize.java:34)
	at org.eclipse.e4.ui.services.internal.events.UIEventHandler.handleEvent(UIEventHandler.java:38)
	at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:206)
	at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:201)
	at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
	at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151)
	at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:131)
	at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:73)
	at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:44)
	at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:55)
	at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:60)
	at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:424)
	at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElementGen(ElementContainerImpl.java:168)
	at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElement(ElementContainerImpl.java:187)
	at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.showElementInWindow(ModelServiceImpl.java:654)
	at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.bringToTop(ModelServiceImpl.java:618)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.delegateBringToTop(PartServiceImpl.java:796)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:1268)
	at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:3228)
	at org.eclipse.ui.internal.WorkbenchPage.lambda$11(WorkbenchPage.java:3118)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:67)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3116)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3086)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3077)
	at bndtools.jareditor.internal.JARTreePart.lambda$new$1(JARTreePart.java:141)
	at org.eclipse.jface.viewers.StructuredViewer$1.run(StructuredViewer.java:779)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:47)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:174)
	at org.eclipse.jface.viewers.StructuredViewer.fireDoubleClick(StructuredViewer.java:776)
	at org.eclipse.jface.viewers.AbstractTreeViewer.handleDoubleSelect(AbstractTreeViewer.java:1580)
	at org.eclipse.jface.viewers.StructuredViewer$4.widgetDefaultSelected(StructuredViewer.java:1205)
	at org.eclipse.jface.util.OpenStrategy.fireDefaultSelectionEvent(OpenStrategy.java:271)
	at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:328)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:91)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4285)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1160)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4083)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3673)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1151)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1042)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:152)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:639)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:339)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:546)
	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:143)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:109)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:439)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:271)
	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
	at java.base/java.lang.reflect.Method.invoke(Method.java:586)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:668)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:605)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1481)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1454)

[c-koell]

@jpstotz should my usecase work ?
To drop a external jar into the workspace without referencing it as maven dependecy ?

[jpstotz]

As I am not the original author of ECD I am not sure if ECD is designed to work directly on JAR files in a Eclipse project.

But a JAR doesn't have to be added via Maven to work with ECD. Instead you can simply add it to the project's build path (context menu "Add to Build path") and then access it via through it's entry in the project's "Referenced Libraries" element.

[jpstotz]

Just fixed the NullPointerException in 4c073ef. Wasn't aware that Eclipse has special JAR File Viewer for JARs that are not on the class-path.

In the end I got a different Exception which explains what is going wrong:

org.eclipse.core.runtime.CoreException: The class file is not on the classpath
	at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.doSetInputCached(ClassFileEditor.java:684)
	at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.lambda$1(ClassFileEditor.java:663)
	at org.eclipse.jdt.core.JavaCore.lambda$0(JavaCore.java:6146)
	at org.eclipse.jdt.internal.core.JavaModelManager.callReadOnly(JavaModelManager.java:5750)
	at org.eclipse.jdt.core.JavaCore.callReadOnly(JavaCore.java:6130)
	at org.eclipse.jdt.core.JavaCore.runReadOnly(JavaCore.java:6145)
	at org.eclipse.jdt.internal.ui.javaeditor.ClassFileEditor.doSetInput(ClassFileEditor.java:663)
	at org.sf.feeling.decompiler.editor.JavaDecompilerClassFileEditor.doSetInput(JavaDecompilerClassFileEditor.java:318)

It seems that Eclipse doesn't allow to set the decompiled source code to an element inside this Jar File Viewer (the elements are read-only).

In my interpretation this means Eclipse and ECD are designed to decompile only classes that are on the class path.