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| Re: Getting NPE using GEF? [message #145871 is a reply to message #145842] |
Sun, 01 August 2004 15:48  |
Eclipse User |
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Originally posted by: rlemaigr.ulb.ac.be
Hello,
> I am using GEF to build a tree like structure by creating a custom =
> draw2d figure and adding new figures to a "contents" in the parent =
> figure.
> I then use an EditPart to create the child figure in the createFigure =
=
> method and then I add it to the parent in the refreshVisuals method.
Maybe the problem is there ?
You must not add yourself the figure to the contentpane of the parent
EditPart in the refreshVisuals method. All the refreshVisuals method
has to do is updating the properties of the (already created and added
to the parent content pane) EditPart's Figure to match
the current state of the EditPart's model object.
GEF adds itself the IFigure returned by createFigure() to the content pa=
ne
of the parent EditPart when it is needed (when the EditPart is created).=
Maybe you already know this (sorry if you do) :
By overriding the refreshVisuals and createFigure methods in a child =
EditPart,
you provide GEF all the information it has to know to create and update =
=
(update
is done once by GEF just after the Figure is created) the Figure of that=
=
child
EditPart.
By overriding the getModelChildren, getContentPane in a parent EditPart,=
(and by implementing the EditPartFactory), you provide GEF all the =
information
it has to know to build the children of the parent EditPart, and where
it must put their Figures.
With these methods implemented, GEF has all it has to know to build the
view/controllers trees by itself, you must not do that yourself (like =
adding
a Figure to its content pane or adding an EditPart to its parent,etc.).
hope this will help,
r=E9gis
> The getChildren method returns object that will generate an instance o=
f =
> the same editorpart as it's parent from the factory. The first level =
=
> works ok, but i get the following NPE when I add a second level:
>
> !ENTRY org.eclipse.ui 4 0 Jul 31, 2004 20:36:55.832
> !MESSAGE java.lang.NullPointerException
> !STACK 0
> java.lang.NullPointerException
> at org.eclipse.draw2d.FigureCanvas.layoutViewport(FigureCanvas. java:2=
14)
> at org.eclipse.draw2d.FigureCanvas.access$4(FigureCanvas.java:2 06)
> at =
> org.eclipse.draw2d.FigureCanvas$3.notifyValidating(FigureCan vas.java:1=
71)
> at =
> org.eclipse.draw2d.UpdateManager.fireValidating(UpdateManage r.java:93)=
> at =
> org.eclipse.draw2d.DeferredUpdateManager.validateFigures(Def erredUpdat=
eManager.java:228)
> at =
> org.eclipse.draw2d.DeferredUpdateManager.performUpdate(Defer redUpdateM=
anager.java:132)
> at =
> org.eclipse.draw2d.DeferredUpdateManager$UpdateRequest.run(D eferredUpd=
ateManager.java:57)
> at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:3 5)
> at =
> org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchr onizer.jav=
a:106)
> at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.jav a:2748=
)
> at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java :2538)=
> at org.eclipse.jface.window.Window.runEventLoop(Window.java:668 )
> at org.eclipse.jface.window.Window.open(Window.java:648)
> at org.eclipse.jface.dialogs.ErrorDialog.open(ErrorDialog.java: 257)
> at org.eclipse.jface.dialogs.ErrorDialog.openError(ErrorDialog. java:3=
19)
> at org.eclipse.jface.dialogs.ErrorDialog.openError(ErrorDialog. java:2=
85)
> at org.eclipse.ui.internal.Workbench$13.run(Workbench.java:1099 )
> at =
> org.eclipse.core.internal.runtime.InternalPlatform.run(Inter nalPlatfor=
m.java:615)
> at org.eclipse.core.runtime.Platform.run(Platform.java:747)
> at org.eclipse.ui.internal.Workbench.restoreState(Workbench.jav a:1029=
)
> at =
> org.eclipse.ui.internal.WorkbenchConfigurer.restoreState(Wor kbenchConf=
igurer.java:167)
> at =
> org.eclipse.ui.application.WorkbenchAdvisor.openWindows(Work benchAdvis=
or.java:652)
> at org.eclipse.ui.internal.Workbench.init(Workbench.java:819)
> at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:1325)
> at =
> org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Work bench.java=
:254)
> at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.j ava:14=
1)
> at =
> org.eclipse.ui.internal.ide.IDEApplication.run(IDEApplicatio n.java:96)=
> at =
> org.eclipse.core.internal.runtime.PlatformActivator$1.run(Pl atformActi=
vator.java:335)
> at =
> org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseS tarter.jav=
a:273)
> at =
> org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseS tarter.jav=
a:129)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at =
> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAcce ssorImpl.j=
ava:39)
> at =
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMe thodAccess=
orImpl.java:25)
> at java.lang.reflect.Method.invoke(Method.java:324)
> at org.eclipse.core.launcher.Main.basicRun(Main.java:183)
> at org.eclipse.core.launcher.Main.run(Main.java:644)
> at org.eclipse.core.launcher.Main.main(Main.java:628)
>
>
> Does anyone know what this could be a symptom of?
>
> Thanks!
>
-- =
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