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
if (doStruct) {
                updatePlus((Item) widget, element);
            }
            if (updateLabels || !equals(element, widget.getData())) {
                doUpdateItem(widget, element, true);
            } else {
                associate(element, (Item) widget);
            }
        }
        if (doStruct) {
            internalRefreshStruct(widget, element, updateLabels);
        } else {
            Item[] children = getChildren(widget);
            if (children != null) {
                for (int i = 0; i < children.length; i++) {
                    Widget item = children[i];
                    Object data = item.getData();
                    if (data != null) {
						internalRefresh(item, data, doStruct, updateLabels);
					}
                }
            }
        }
    }
    /**
     * Update the structure and recurse. Items are updated in updateChildren,
     * as needed.
     * @param widget
     * @param element
     * @param updateLabels