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/AbstractTreeViewer.java
protected abstract Item[] getSelection(Control control);
    
    protected List getSelectionFromWidget() {
        Widget[] items = getSelection(getControl());
        ArrayList list = new ArrayList(items.length);
        for (int i = 0; i < items.length; i++) {
            Widget item = items[i];
            Object e = item.getData();
            if (e != null) {
				list.add(e);
			}
        }
        return list;
    }
    /**
     * Handles a tree collapse event from the SWT widget.
     * 
     * @param event
     *           the SWT tree event
     */
    protected void handleTreeCollapse(TreeEvent event) {
        if (event.item.getData() != null) {
            fireTreeCollapsed(new TreeExpansionEvent(this, event.item.getData()));
        }
    }
    /**
     * Handles a tree expand event from the SWT widget.
     * 
     * @param event
     *           the SWT tree event