Java JTree set discontiguous tree selection mode

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeSelectionModel;

public class Main {
   public static void main(String[] args) {
      DefaultMutableTreeNode rootNode = new DefaultMutableTreeNode("Root");
      DefaultMutableTreeNode a = new DefaultMutableTreeNode("A");
      rootNode.add(a);//  w  w w. j a va2s. c om

      DefaultMutableTreeNode a1 = new DefaultMutableTreeNode("1");
      a.add(a1);
      DefaultMutableTreeNode a2 = new DefaultMutableTreeNode("2");
      a.add(a2);

      
      DefaultMutableTreeNode b = new DefaultMutableTreeNode("B");
      rootNode.add(b);
      DefaultMutableTreeNode b1 = new DefaultMutableTreeNode("1");
      b.add(b1);


      JTree tree = new JTree(rootNode);
      tree.getSelectionModel().setSelectionMode(
            TreeSelectionModel.DISCONTIGUOUS_TREE_SELECTION);
      
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      f.add(new JScrollPane(tree));
      f.setSize(250, 250);
      f.setVisible(true);
   }
}