title: NoClassDefFoundError in Eclipse RCP application
body: <p>In our application we <em>sometimes</em> (about 1 out of 10 times) get a <a href="http://download.oracle.com/javase/1.4.2/docs/api/java/lang/NoClassDefFoundError.html" rel="nofollow noreferrer">NoClassDefFoundError</a> when trying to instantiate a class. It happens when a project is opened from without our application.</p>
  
  <p>The full stack trace looks like this:</p>
  
  <pre><code>!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
  </code></pre>
  
  <p>These related questions didn't answer my problem:</p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/596999/noclassdeffounderror-on-jface-fontregistry">NoClassDefFoundError on JFace FontRegistry</a></li>
  <li><a href="https://stackoverflow.com/questions/2306133/getting-class-not-found-exception-when-running-in-eclipse">Getting class not found Exception when running in eclipse</a></li>
  </ul>
  
  <p>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?</p>
  
  <p>Can anyone help me fix this problem?</p>