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
if (parentItem != null) {
							index = parentItem.indexOf(item);
						} else {
							index = getTree().indexOf(item);
						}
						virtualLazyUpdateWidget(parentItem == null ? (Widget)getTree() : parentItem, index);
					}
				}
			});
		}
	}
	/**
	 * Initializes the tree viewer implementation.
	 */
	private void initTreeViewerImpl() {
		treeViewerImpl = new TreeEditorImpl(this) {
			Rectangle getBounds(Item item, int columnNumber) {
				return ((TreeItem) item).getBounds(columnNumber);
			}
			int getColumnCount() {
				return getTree().getColumnCount();
			}
			Item[] getSelection() {
				return getTree().getSelection();
			}
			void setEditor(Control w, Item item, int columnNumber) {
				treeEditor.setEditor(w, (TreeItem) item, columnNumber);
			}
			void setSelection(IStructuredSelection selection, boolean b) {
				TreeViewer.this.setSelection(selection, b);