Bug 163357 [Viewers] NullPointerException on AbstractTreeViewer.remove(path, index)
I20061102-1715 It's possible to get an NPE when removing an element from a tree viewer. The remove API accepts a "parent path" and "child index". It is possible to specify an empty tree path for the parent to indicate the root element. However, the remove code eventually trys to find the widget associated with the "last segment" of the parent path. This results in null, and an NPE: Caused by: java.lang.NullPointerException at org.eclipse.jface.viewers.CustomHashtable.hashCode(CustomHashtable.java:265) at org.eclipse.jface.viewers.CustomHashtable.get(CustomHashtable.java:237) at org.eclipse.jface.viewers.StructuredViewer.findItems(StructuredViewer.java:769) at org.eclipse.jface.viewers.AbstractTreeViewer.internalFindItem(AbstractTreeViewer.java:173) at org.eclipse.jface.viewers.AbstractTreeViewer.internalFindItems(AbstractTreeViewer.java:153) at org.eclipse.jface.viewers.TreeViewer$8.run(TreeViewer.java:1017) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1326) at org.eclipse.jface.viewers.TreeViewer.remove(TreeViewer.java:1005) at org.eclipse.debug.internal.ui.viewers.model.ChildrenUpdate.performUpdate(ChildrenUpdate.java:62) at org.eclipse.debug.internal.ui.viewers.model.ViewerUpdateMonitor$1.runInUIThread(ViewerUpdateMonitor.java:43) at org.eclipse.ui.progress.UIJob$1.run(UIJob.java:94) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:123) ... 20 more
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
Item[] items = getChildren(widget);
			for (int i = 0; i < items.length; i++) {
				Item item = items[i];
				Object data = item.getData();
				if (data != null) {
					virtualRefreshChildCounts(item, data);
				}
			}
		}
	}
	/*
	 * To unmap elements correctly, we need to register a dispose listener with
	 * the item if the tree is virtual.
	 */
	protected void mapElement(Object element, final Widget item) {
		super.mapElement(element, item);
		
		if ((getTree().getStyle() & SWT.VIRTUAL) != 0) {
			
			
			if (item.getData(VIRTUAL_DISPOSE_KEY) == null) {
				item.setData(VIRTUAL_DISPOSE_KEY, Boolean.TRUE);
				item.addDisposeListener(new DisposeListener() {
					public void widgetDisposed(DisposeEvent e) {
						if (!treeIsDisposed) {
							Object data = item.getData();
							if (usingElementMap() && data != null) {
								unmapElement(data, item);
							}
						}