NoClassDefFoundError in Eclipse RCP application

Question

In our application we sometimes (about 1 out of 10 times) get a NoClassDefFoundError when trying to instantiate a class. It happens when a project is opened from without our application.

The full stack trace looks like this:

!ENTRY org.eclipse.jface 4 2 2011-11-18 12:45:33.941
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jface".
!STACK 0
java.lang.NoClassDefFoundError: com.mycompany.products.myapp.gui.model.provider.EMyAppObjectItemProvider
    at com.mycompany.products.myapp.gui.model.provider.MyappguimodelItemProviderAdapterFactory.createMyAppGuiPortAdapter(MyappguimodelItemProviderAdapterFactory.java:159)
    at com.mycompany.products.myapp.gui.model.util.MyappguimodelAdapterFactory$1.caseMyAppGuiPort(MyappguimodelAdapterFactory.java:185)
    at com.mycompany.products.myapp.gui.model.util.MyappguimodelAdapterFactory$1.caseMyAppGuiPort(MyappguimodelAdapterFactory.java:1)
    at com.mycompany.products.myapp.gui.model.util.MyappguimodelSwitch.doSwitch(MyappguimodelSwitch.java:226)
    at org.eclipse.emf.ecore.util.Switch.doSwitch(Switch.java:59)
    at org.eclipse.emf.ecore.util.Switch.doSwitch(Switch.java:75)
    at com.mycompany.products.myapp.gui.model.util.MyappguimodelAdapterFactory.createAdapter(MyappguimodelAdapterFactory.java:462)
    at org.eclipse.emf.common.notify.impl.AdapterFactoryImpl.createAdapter(AdapterFactoryImpl.java:133)
    at org.eclipse.emf.common.notify.impl.AdapterFactoryImpl.adaptNew(AdapterFactoryImpl.java:107)
    at org.eclipse.emf.common.notify.impl.AdapterFactoryImpl.adapt(AdapterFactoryImpl.java:93)
    at com.mycompany.products.myapp.gui.model.provider.MyappguimodelItemProviderAdapterFactory.adapt(MyappguimodelItemProviderAdapterFactory.java:1127)
    at org.eclipse.emf.edit.provider.ComposedAdapterFactory.adapt(ComposedAdapterFactory.java:300)
    at org.eclipse.emf.edit.provider.ComposedAdapterFactory.adapt(ComposedAdapterFactory.java:277)
    at org.eclipse.emf.edit.provider.ComposedAdapterFactory.adapt(ComposedAdapterFactory.java:264)
    at org.eclipse.emf.edit.ui.provider.AdapterFactoryLabelProvider.getColumnText(AdapterFactoryLabelProvider.java:496)
    at org.eclipse.jface.viewers.TableColumnViewerLabelProvider.update(TableColumnViewerLabelProvider.java:70)
    at org.eclipse.jface.viewers.ViewerColumn.refresh(ViewerColumn.java:152)
    at org.eclipse.jface.viewers.AbstractTableViewer.doUpdateItem(AbstractTableViewer.java:399)
    at org.eclipse.jface.viewers.StructuredViewer$UpdateItemSafeRunnable.run(StructuredViewer.java:485)
    at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
    at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:49)
    at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
    at org.eclipse.jface.viewers.StructuredViewer.updateItem(StructuredViewer.java:2167)
    at org.eclipse.jface.viewers.AbstractTableViewer.createItem(AbstractTableViewer.java:277)
    at org.eclipse.jface.viewers.AbstractTableViewer.internalRefreshAll(AbstractTableViewer.java:757)
    at org.eclipse.jface.viewers.AbstractTableViewer.internalRefresh(AbstractTableViewer.java:649)
    at org.eclipse.jface.viewers.AbstractTableViewer.internalRefresh(AbstractTableViewer.java:636)
    at org.eclipse.jface.viewers.AbstractTableViewer$2.run(AbstractTableViewer.java:592)
    at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1443)
    at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1404)
    at org.eclipse.jface.viewers.AbstractTableViewer.inputChanged(AbstractTableViewer.java:590)
    at org.eclipse.jface.viewers.ContentViewer.setInput(ContentViewer.java:280)
    at org.eclipse.jface.viewers.StructuredViewer.setInput(StructuredViewer.java:1690)
    at com.mycompany.products.myapp.gui.views.port.composites.Ipv4PortComposite.projectOpenedOrClosed(Ipv4PortComposite.java:732)
    at com.mycompany.products.myapp.gui.project.MyAppResourceController.tellOpenCloseListeners(MyAppResourceController.java:186)
    at com.mycompany.products.myapp.gui.actions.project.MyAppGuiResourceController.openProject(MyAppGuiResourceController.java:266)
    at com.mycompany.products.myapp.gui.project.MyAppResourceController.open(MyAppResourceController.java:592)
    at com.mycompany.products.myapp.gui.project.MyAppResourceController.openWithoutUpdating(MyAppResourceController.java:612)
    at com.mycompany.products.myapp.gui.actions.file.MyAppRecentProjectAction.run(MyAppRecentProjectAction.java:55)
    at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
    at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
        at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
    at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
    at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
    at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
    at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
    at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
    at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
    at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
    at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
    at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
    at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
    at com.mycompany.products.myapp.gui.MyAppApplication.start(MyAppApplication.java:175)
    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:344)
    at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
    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:616)
    at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
    at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
    at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
    at org.eclipse.equinox.launcher.M

These related questions didn't answer my problem:

• NoClassDefFoundError on JFace FontRegistry
• Getting class not found Exception when running in eclipse

From what I've read this exception occurs when the class is not found in the runtime class-path. So I think it would be useful if I could print the runtime search paths before the actual attempt at instantiation. This way I can check if there is any difference in the 1/10 times it fails. However, I haven't found yet how to get the list of runtime search paths. Any hints on how to get them?

Can anyone help me fix this problem?

Answer 1

For classloading issues Java offers some tools. Look Do you really get class loaders on Slideshare. I once had a similar problem with the help system of Eclipse which I integrated in my RCP product. When started within the IDE everything worked fine but when starting the exported product the help system just doesn't come up.

Answer 2

Do you get this when starting the application? This sounds like some bundles haven't been initialized at that point. OSGi will start modules based on the dependencies, but there's a random element when you don't have the proper dependencies set in place. I would suggest looking at that. If you want more info, you can use the OSGi console to examine your environment:

http://www.ibm.com/developerworks/library/os-ecl-osgiconsole/index.html

Hope this helps.

Answer 3

Try to run your application in the debugger with the OSGi console enabled ( -console ). Add a Class breakpoint for NoClassDefFoundError or alternatively on the offending line of code ( MyappguimodelItemProviderAdapterFactory.java:159 ).

And, when the breakpoint is hit:

• find the bundle ID of the bundle with MyappguimodelItemProviderAdapterFactory - eg with the ss OSGi command
• find the complete status of the bundle with the bundle <id> OSGi command
• check whether the package in question - com.mycompany.products.myapp.gui.model.provider - is wired correctly in the "Imported Packages" section

I don't know what can be wrong, but you should check that

• the correct package wiring has been set up - possibly using packages com.mycompany.products.myapp.gui.model.provider OSGi command to find all the providers
• the bundle with EMyAppObjectItemProvider actually includes the class - you can find the jar used by OSGi with the status OSGi command (don't assume you know :-))