Bug 138608 [Viewers] JFace AbstractTreeViewer: itemExists doesn't handle equal tree entries
I use a TreeViewer with - setUseHashLookup(true) - without any sorter or filter - with a comparer When I try to add an object that is equal to an existing entry in the tree, it will not be added. This is because the method private boolean itemExists(Item[] items, Object element) { if(usingElementMap()) { return findItem(element) != null; } for (int i = 0; i < items.length; i++) { if(items[i].getData().equals(element)) { return true; } } return false; } takes a shortcut if there is an element map, but the shortcut doesn't handle the 'multiple equal elements' case. There is a workaround, however: Setting a dummy sorter will avoid the call to itemExists and multiple equal elements can be added to the tree.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/AbstractTreeViewer.java
* (non-Javadoc)
     * @see org.eclipse.jface.viewers.StructuredViewer#handleDoubleSelect(org.eclipse.swt.events.SelectionEvent)
     */
	protected void handleDoubleSelect(SelectionEvent event) {
		
		Control control = getControl();
		if (control != null && !control.isDisposed()) {
			
			
			
			
			ISelection selection;
			if (event.item != null && event.item.getData() != null) {
				
				
				TreePath treePath = getTreePathFromItem((Item) event.item);
				selection = new TreeSelection(treePath);
				 
				
			}
			else {
				selection = getSelection();
				updateSelection(selection);
			}
			fireDoubleClick(new DoubleClickEvent(this, selection));
		}
	}
	/**
     * Handles a tree collapse event from the SWT widget.
     *