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
}
        }
        
        Item[] items = getChildren(parent);
        for (int i = 0; i < items.length; i++) {
            Item item = items[i];
            Widget o = internalFindItem(item, element);
            if (o != null) {
				return o;
			}
        }
        return null;
    }
    
    protected void internalRefresh(Object element) {
        internalRefresh(element, true);
    }
    
    protected void internalRefresh(Object element, boolean updateLabels) {
        
        if (element == null) {
            internalRefresh(getControl(), getRoot(), true, updateLabels);
            return;
        }
        Widget[] items = findItems(element);
        if (items.length != 0) {
			for (int i = 0; i < items.length; i++) {
				
				internalRefresh(items[i], element, true, updateLabels);
			}