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
}
        }
    }
    
    protected Widget doFindInputItem(Object element) {
        
        Object root = getRoot();
        if (root == null) {
			return null;
		}
        if (equals(root, element)) {
			return getControl();
		}
        return null;
    }
    
    protected Widget doFindItem(Object element) {
        
        Object root = getRoot();
        if (root == null) {
			return null;
		}
        Item[] items = getChildren(getControl());
        if (items != null) {
            for (int i = 0; i < items.length; i++) {
                Widget o = internalFindItem(items[i], element);
                if (o != null) {
					return o;
				}
            }