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
handleTreeCollapse(event);
            }
        });
    }
    /*
     * (non-Javadoc) Method declared on StructuredViewer. Builds the initial
     * tree and handles the automatic expand feature.
     */
    protected void inputChanged(Object input, Object oldInput) {
        preservingSelection(new Runnable() {
            public void run() {
                Control tree = getControl();
                boolean useRedraw = true;
                
                
                if (useRedraw) {
					tree.setRedraw(false);
				}
                removeAll(tree);
                tree.setData(getRoot());
                createChildren(tree);
                internalExpandToLevel(tree, expandToLevel);
                if (useRedraw) {
					tree.setRedraw(true);
				}
            }
        });
    }
    /**
     * Recursively collapses the subtree rooted at the given widget to the