Method valueForPathChanged in TreeModel interface (Swing)

Question

I am implementing TreeModel interface and have implemented all methods except for the valueForPathChanged.

In my case, the values are not going to be programatically changed.

Why TreeModel interface contains this method? Is it used by JTree in any circumstances, or I am safe to leave it unimplemented?

Code for the reference, it works. I am just concerned whether valueForPathChanged is required by the JTree:

class ParamsTreeModel implements TreeModel  {
    private final TreeRoot root;
    private final List<TreeModelListener> listeners = new ArrayList<TreeModelListener>();
    ParamsTreeModel(TreeRoot root)  {
        this.root = root;
    }

    @Override
    public void addTreeModelListener(TreeModelListener l) {
        listeners.add(l);
    }

    @Override
    public Object getChild(Object parent, int index) {
        if(parent instanceof Param) return null;
        if(structuredMap.containsKey(parent))   {
            return structuredMap.get(parent).get(index);
        }
        // Root
        return partNames.get(index);
    }

    @Override
    public int getChildCount(Object parent) {
        if(parent instanceof Param) return 0;
        if(parent instanceof TreeRoot)  return partNames.size();
        return structuredMap.get(parent).size();
    }

    @Override
    public int getIndexOfChild(Object parent, Object child) {
        if(parent instanceof TreeRoot)  return partNames.indexOf(child);
        return structuredMap.get(parent).indexOf(child);
    }

    @Override
    public Object getRoot() {
        return root;
    }

    @Override
    public boolean isLeaf(Object node) {
        return (node instanceof Param);
    }

    @Override
    public void removeTreeModelListener(TreeModelListener l) {
        listeners.remove(l);
    }

    @Override
    public void valueForPathChanged(TreePath path, Object newValue) {
        // TODO Auto-generated method stub

    }

}

Answer 1

While you are required to implement the valueForPathChanged() method, as defined in the TreeModel interface, you are free to leave it empty. FileTreeModel, cited here, is an example. The valueForPathChanged() method is typically used to support cell editing. As a concrete example, the implementation in DefaultTreeModel, seen here, "sets the user object of the TreeNode identified by path and posts a node changed [event]."