Nullpointer Exception after registering a Designer Extension

[chris889]

I am trying to create my own Activiti Designer Extension (following the explanations in the User Guide, Chapter "Extending Activiti Designer"). After registering my extension and opening a new or existing diagram, I'm getting a null-pointer exception. Please find the stacktrace from the log file below

!ENTRY org.eclipse.graphiti 4 0 2011-12-31 12:50:59.425
!MESSAGE Method 'setInput(IEditorInput)': Can not open the modifier. Details null
Details: java.lang.NullPointerException
   at java.util.zip.ZipFile.getInputStream(ZipFile.java:193)
   at java.util.jar.JarFile.getInputStream(JarFile.java:385)
   at org.activiti.designer.property.extension.JarClassLoader.loadClassData(JarClassLoader.java:92)
   at org.activiti.designer.property.extension.JarClassLoader.loadClass(JarClassLoader.java:61)
   at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
   at remap.workflow.activiti.designer.InternalReminderTask.getName(InternalReminderTask.java:13)
   at org.activiti.designer.diagram.ActivitiToolBehaviorProvider.getPalette(ActivitiToolBehaviorProvider.java:531)
   at org.eclipse.graphiti.ui.internal.editor.GFPaletteRoot.updatePaletteEntries(GFPaletteRoot.java:104)
   at org.eclipse.graphiti.ui.internal.editor.GFPaletteRoot.<init>(GFPaletteRoot.java:79)
   at org.eclipse.graphiti.ui.internal.editor.DiagramEditorInternal.createPaletteRoot(DiagramEditorInternal.java:459)
   at org.eclipse.graphiti.ui.internal.editor.DiagramEditorInternal.getPaletteRoot(DiagramEditorInternal.java:923)
   at org.eclipse.gef.ui.parts.GraphicalEditorWithFlyoutPalette.setEditDomain(GraphicalEditorWithFlyoutPalette.java:145)
   at org.eclipse.graphiti.ui.internal.editor.DiagramEditorInternal.setConfigurationProvider(DiagramEditorInternal.java:1593)
   at org.eclipse.graphiti.ui.internal.editor.DiagramEditorInternal.setInput(DiagramEditorInternal.java:618)
   at org.activiti.designer.eclipse.editor.ActivitiDiagramEditor.setInput(ActivitiDiagramEditor.java:115)
   at org.eclipse.gef.ui.parts.GraphicalEditor.init(GraphicalEditor.java:346)
   at org.eclipse.graphiti.ui.internal.editor.DiagramEditorInternal.init(DiagramEditorInternal.java:1093)
   at org.activiti.designer.eclipse.editor.ActivitiDiagramEditor.init(ActivitiDiagramEditor.java:51)
   at org.eclipse.ui.internal.EditorManager.createSite(EditorManager.java:798)
   at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:647)
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Any idea what might gone wrong? It seems that it's unable to load the class of my jar file..

Thanks a lot and happy new year! 😉

[chris889]

I found the issue myself. The problem was that my extension was referencing some other external libraries (to pull in some constants). This obviousely caused problems to the designer since those libraries were not available at the time the time the designer was running. It would be nice if the JarClassLoader class would give a proper error message instead.