import  java.awt.Dimension;
 import  java.awt.GridLayout;

 import  javax.swing.JFrame;
 import  javax.swing.JPanel;
 import  javax.swing.JTree;
 import  javax.swing.UIManager;
 import  javax.swing.tree.DefaultMutableTreeNode;

 public   class  TreeDemo
     extends  JPanel {

     private  JTree tree;

     public  TreeDemo() {
         super ( new  GridLayout( 1 ,  0 ));

        // Наполнение дерева

        DefaultMutableTreeNode top =  new  DefaultMutableTreeNode("top");
        DefaultMutableTreeNode level1;
        DefaultMutableTreeNode level2;

        top.add(level1 =  new  DefaultMutableTreeNode("11"));
        top.add( new  DefaultMutableTreeNode("12"));
        top.add( new  DefaultMutableTreeNode("13"));

        level1.add(level2 =  new  DefaultMutableTreeNode("21"));
        level1.add( new  DefaultMutableTreeNode("22"));

        level2.add( new  DefaultMutableTreeNode("31"));
        level2.add( new  DefaultMutableTreeNode("32"));
        level2.add( new  DefaultMutableTreeNode("33"));

        tree =  new  JTree(top);

        tree.setRootVisible(false);
        tree.setRowHeight( 30 );

        // Попытка сокрытия крестика
        tree.setShowsRootHandles(false);

        tree.setPreferredSize( new  Dimension( 500 ,  300 ));

        add(tree);
    }

     private   static   void  createAndShowGUI() {

         try  {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
         catch  (Exception e) {
            System.err.println("Couldn't use system look and feel.");
        }

        JFrame frame =  new  JFrame("TreeDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        TreeDemo newContentPane =  new  TreeDemo();
        newContentPane.setOpaque(true);
        frame.setContentPane(newContentPane);

        frame.pack();
        frame.setVisible(true);
    }

     public   static   void  main(String[] args) {
        javax.swing.SwingUtilities.invokeLater( new  Runnable() {

             public   void  run() {
                createAndShowGUI();
            }
        });
    }
}

JTree tree =  new  JTree();
BasicTreeUI ui =  new  BasicTreeUI() {

     public  Icon getCollapsedIcon() {
         return   null ;
    }

     public  Icon getExpandedIcon() {
         return   null ;
    }
};
tree.setUI(ui);