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
}
        setSelection(newSelection);
        
        
        
        
        
        if (reveal && newSelection.size() > 0) {
            showItem((Item) newSelection.get(0));
        }
    }
    /**
     * Shows the given item.
     * 
     * @param item
     *           the item
     */
    protected abstract void showItem(Item item);
    /**
     * Updates the tree items to correspond to the child elements of the given
     * parent element. If null is passed for the children, this method obtains
     * them (only if needed).
     * 
     * @param widget
     *           the widget
     * @param parent
     *           the parent element
     * @param elementChildren
     *           the child elements, or null
     * @deprecated this is no longer called by the framework