[trash@dagmarbuggle.de]

Hi,
I'm creating an App which main part consists of a JFace TreeViewer. My users must have the possibilities to completely refresh the displayed data, so the domain model is completely renewed.
I'm cleaning my domain model, reloading it and refreshing the interfaces to the viewer as visible in the follwing method calls:

		disposeTreeColumns();
		frontendModuleService.clean();
		load();
		createTreeColumns();
		frontendModuleService.refresh();
		treeviewer.setInput(ModelProvider.getInstance().getModules());
		treeviewer.refresh(true);

frontendModuleService.refresh() refreshes the LabelProvider by adding the new columns.
Everything works fine until from treeviewer.setInput(ModelProvider.getInstance().ge tModules()) is called. It produces a NullPointerException, which is thrown by org.eclipse.jface.viewers.ViewerColumn.refresh(Vie werColumn.java:145). In that method getLabelProvider() is called, which is null, but when treeviewer.setInput() was called, everything was fine!!! My domain model object as well is properly refilled.
So what happens there? Am I completely wrong with my approach to refresh TreeViewer?

Here the stack trace, to be complete:

java.lang.NullPointerException
	at org.eclipse.jface.viewers.ViewerColumn.refresh(ViewerColumn.java:145)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:932)
	at org.eclipse.jface.viewers.AbstractTreeViewer$UpdateItemSafeRunnable.run(AbstractTreeViewer.java:102)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
	at org.eclipse.core.runtime.Platform.run(Platform.java:880)
	at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:1012)
	at org.eclipse.jface.viewers.StructuredViewer$UpdateItemSafeRunnable.run(StructuredViewer.java:466)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:37)
	at org.eclipse.core.runtime.Platform.run(Platform.java:880)
	at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
	at org.eclipse.jface.viewers.StructuredViewer.updateItem(StructuredViewer.java:2041)
	at org.eclipse.jface.viewers.AbstractTreeViewer.createTreeItem(AbstractTreeViewer.java:827)
	at org.eclipse.jface.viewers.AbstractTreeViewer$1.run(AbstractTreeViewer.java:802)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
	at org.eclipse.jface.viewers.AbstractTreeViewer.createChildren(AbstractTreeViewer.java:776)
	at org.eclipse.jface.viewers.TreeViewer.createChildren(TreeViewer.java:634)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalExpandToLevel(AbstractTreeViewer.java:1702)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalExpandToLevel(AbstractTreeViewer.java:1712)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalInitializeTree(AbstractTreeViewer.java:1491)
	at org.eclipse.jface.viewers.TreeViewer.internalInitializeTree(TreeViewer.java:823)
	at org.eclipse.jface.viewers.AbstractTreeViewer$5.run(AbstractTreeViewer.java:1474)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1365)
	at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:397)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1328)
	at org.eclipse.jface.viewers.AbstractTreeViewer.inputChanged(AbstractTreeViewer.java:1467)
	at org.eclipse.jface.viewers.ContentViewer.setInput(ContentViewer.java:274)
	at org.eclipse.jface.viewers.StructuredViewer.setInput(StructuredViewer.java:1603)
	at de.doxanize.divsddrcp.treeviewer.View.refresh(View.java:318)

Any help would be great!
Thx
Dagmar

[hmausolf]

Hi Dagmar,

what if you leave out the treeviewer.setInput() call? In my opinion, it is sufficient to set the input only once on initialization. I have written an application that refreshes a TableViewer on demand of the user, but without the need to rearrange columns. I just call tableviewer.refresh(true), and everything works just great.

Regards from Hamburg,
Heiko

[trash@dagmarbuggle.de]

Hi Heiko,
thx for your answer. I just tried it and noticed, that at least there is no difference in throwing this mysterious exception. The second thing is that I noticed that treeviewer.refresh(true) is the real point where the exception is thrown. So far so good, this thing is at least a bit less foggy now - but I now have to go on exploring what happens.
regards
dagmar