private  EventListenerList listenerList =  new  EventListenerList();

     public   void  addTreeModelListener(TreeModelListener l) {                                                                                
        listenerList.add(TreeModelListener. class , l);                                                                                      
    }                                                                                                                                      
                                                                                                                                           
     public   void  removeTreeModelListener(TreeModelListener l) {                                                                             
        listenerList.remove(TreeModelListener. class , l);                                                                                   
    }                                                                                                                                      

     protected   void  fireTreeStructureChanged(TreePath path) {                                                                               
        TreeModelEvent event =  new  TreeModelEvent( this , path);                                                                             
        EventListener[] listeners = listenerList.getListeners(TreeModelListener. class );                                                    
         for  (EventListener listener : listeners) {                                                                                         
            ((TreeModelListener) listener).treeStructureChanged(event);                                                                    
        }                                                                                                                                  
    }