Bug 129193 [JFace] Setting the sorter on AbstractTreeViewer before input can cause NPE
I have a scenario with a subclass of TreePathViewerSorter is set on a subclass of AbstractTreeViewer. AbstractTreeViewer.setSorter() calls refresh, which eventually ends up here: // AbstractTreeViewer: /* (non-Javadoc) * @see org.eclipse.jface.viewers.StructuredViewer#getSortedChildren(java.lang.Object) */ protected Object[] getSortedChildren(Object parentElementOrTreePath) { Object[] result = getFilteredChildren(parentElementOrTreePath); ViewerSorter sorter = getSorter(); if (sorter instanceof TreePathViewerSorter) { TreePathViewerSorter tpvs = (TreePathViewerSorter) sorter; // be sure we're not modifying the original array from the model result = (Object[]) result.clone(); TreePath path = null; if (parentElementOrTreePath instanceof TreePath) { path = (TreePath) parentElementOrTreePath; } else { (1) Object parent = parentElementOrTreePath; (2) Widget w = internalGetWidgetToSelect(parent); if (w != null) { path = internalGetSorterParentPath(w, sorter); } if (path == null) path = TreePath.EMPTY.createChildPath(parentElementOrTreePath); } tpvs.sort(this, path, result); } else if (sorter != null) { // be sure we're not modifying the original array from the model result = (Object[]) result.clone(); sorter.sort(this, result); } return result; } At line (1) parent is null and at line (2) it eventually gets down into findItems(): // StructuredViewer: protected final Widget[] findItems(Object element) { Widget result = doFindInputItem(element); if (result != null) return new Widget[] { result }; // if we have an element map use it, otherwise search for the item. if (usingElementMap()) { (3) Object widgetOrWidgets = elementMap.get(element); if (widgetOrWidgets==null) { return NO_WIDGETS; } else if (widgetOrWidgets instanceof Widget) { return new Widget[] {(Widget) widgetOrWidgets}; } else { return (Widget[])widgetOrWidgets; } } result = doFindItem(element); return result == null ? NO_WIDGETS : new Widget[] { result }; } Here at (3), element is null, and the HashMap throws an NPE when trying to call key.hashCode() (since key is null).
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/TreeViewer.java
}
	/**
	 * Returns this tree viewer's tree control.
	 * 
	 * @return the tree control
	 */
	public Tree getTree() {
		return tree;
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.viewers.AbstractTreeViewer#hookControl(org.eclipse.swt.widgets.Control)
	 */
	protected void hookControl(Control control) {
		super.hookControl(control);
		Tree treeControl = (Tree) control;
		treeControl.addMouseListener(new MouseAdapter() {
			public void mouseDown(MouseEvent e) {
				treeViewerImpl.handleMouseDown(e);
			}
		});
		if ((treeControl.getStyle() & SWT.VIRTUAL) != 0) {
			treeControl.addDisposeListener(new DisposeListener(){
				public void widgetDisposed(DisposeEvent e) {
					treeIsDisposed = true;
					unmapAllElements();
				}});
			treeControl.addListener(SWT.SetData, new Listener(){
				public void handleEvent(Event event) {