What steps will reproduce the problem?
1. Load a test Alloy spec that has a solution instance
2. Select the solution *.xml file
3. Context menu => open with Alloy Answer Viewer
What is the expected output?
A new Eclipse viewer with the A4 visualization
What do you see instead?
At line 360, viewer == null.
This will cause a NPE.
Thread [main] (Suspended (breakpoint at line 360 in MultiPageEditor))
MultiPageEditor.addPage(String, URL) line: 360
MultiPageEditor.createPage2() line: 252
MultiPageEditor.createPages() line: 386
MultiPageEditor(MultiPageEditorPart).createPartControl(Composite) line: 276
EditorReference.createPartHelper() line: 596
EditorReference.createPart() line: 372
EditorReference(WorkbenchPartReference).getPart(boolean) line: 566
EditorReference.getEditor(boolean) line: 214
WorkbenchPage.busyOpenEditorBatched(IEditorInput, String, boolean, int)
line: 2595
WorkbenchPage.busyOpenEditor(IEditorInput, String, boolean, int) line: 2528
WorkbenchPage.access$10(WorkbenchPage, IEditorInput, String, boolean, int)
line: 2520
WorkbenchPage$9.run() line: 2505
BusyIndicator.showWhile(Display, Runnable) line: 67
WorkbenchPage.openEditor(IEditorInput, String, boolean, int) line: 2500
OpenWithMenu.openEditor(IEditorDescriptor) line: 288
OpenWithMenu.access$0(OpenWithMenu, IEditorDescriptor) line: 280
OpenWithMenu$2.handleEvent(Event) line: 184
EventTable.sendEvent(Event) line: 66
MenuItem(Widget).sendEvent(Event) line: 928
Display.runDeferredEvents() line: 3348
Display.readAndDispatch() line: 2968
Workbench.runEventLoop(Window$IExceptionHandler, Display) line: 1930
Workbench.runUI() line: 1894
Workbench.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 422
PlatformUI.createAndRunWorkbench(Display, WorkbenchAdvisor) line: 149
IDEApplication.run(Object) line: 95
PlatformActivator$1.run(Object) line: 78
EclipseAppLauncher.runApplication(Object) line: 92
EclipseAppLauncher.start(Object) line: 68
EclipseStarter.run(Object) line: 400
EclipseStarter.run(String[], Runnable) line: 177
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not
available [native method]
NativeMethodAccessorImpl.invoke(Object, Object[]) line: 64
DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43
Method.invoke(Object, Object...) line: 615
Main.invokeFramework(String[], URL[]) line: 336
Main.basicRun(String[]) line: 280
Main.run(String[]) line: 977
Main.main(String[]) line: 952
Please use labels and text to provide additional information.
At line 360, the state of viz[0] is consistent with the call to
viz[0].loadXML(...) from line 348. However, since the Swing/SWT
visualization runs asynchronously w.r.t. there is a significant potential
for a race condition with the thread that executes the code in
MultiPageEditor, line 359:
final VizViewer viewer = viz[0].getViewer();
If this code executes "too early", then viewer == null and we get NPE at
line 360.
The workaround is either to ask the A4 developers to make getViewer() a
blocking call to ensure it returns a non-null answer once the Swing/SWT
thread has performed the necessary update work or for A4E to define a
wrapper to do this.
Original issue reported on code.google.com by nicolas....@gmail.com on 12 Feb 2008 at 10:34
Original issue reported on code.google.com by
nicolas....@gmail.comon 12 Feb 2008 at 10:34