treemodeleventdemo.java

《java事件处理指南》一书的代码,好东西

import javax.swing.*;
import javax.swing.tree.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class TreeModelEventDemo extends JFrame implements ActionListener
{
   private JTree tree;
   private JButton button;
   private DefaultTreeModel model;

   public TreeModelEventDemo() 
   {
/*  A Collection of DefaultMutableTreeNode objects are created that  */
/*  will form the components of a tree.                              */

      DefaultMutableTreeNode league = 
               new DefaultMutableTreeNode("Soccer League");

      DefaultMutableTreeNode north = 
                  new DefaultMutableTreeNode("North Division");
      DefaultMutableTreeNode south = 
                  new DefaultMutableTreeNode("South Divison");

      DefaultMutableTreeNode jets = 
                      new DefaultMutableTreeNode("Jets");
      DefaultMutableTreeNode raiders = 
                      new DefaultMutableTreeNode("Raiders");
      DefaultMutableTreeNode fins = 
                      new DefaultMutableTreeNode("Fins");
      DefaultMutableTreeNode shooters = 
                      new DefaultMutableTreeNode("Shooters");
      DefaultMutableTreeNode lions = 
                      new DefaultMutableTreeNode("Lions");
      DefaultMutableTreeNode tigers = 
                      new DefaultMutableTreeNode("Tigers");

/*  The node hierarchy is loaded into a DefaultTreeModel object.   */
/*  The tree model registers a TreeModelListener.                  */

      model = new DefaultTreeModel(league);
      model.insertNodeInto(north, league, 0);
      model.insertNodeInto(south, league, 1);
      model.insertNodeInto(jets, north, 0);
      model.insertNodeInto(raiders, north, 1);
      model.insertNodeInto(fins, north, 2);
      model.insertNodeInto(shooters, south, 0);
      model.insertNodeInto(lions, south, 1);
      model.insertNodeInto(tigers, south, 2);
      model.addTreeModelListener(new TreeModelHandler());

/*  A JTree object is created using the previously created tree model.  */

      tree = new JTree(model);
      tree.setShowsRootHandles(true);
      tree.expandRow(1);

      button = new JButton("remove");
      button.setBorder(BorderFactory.createRaisedBevelBorder());
      button.addActionListener(this);

      JPanel panel = new JPanel();
      panel.add(button);

      getContentPane().add( new JScrollPane(tree), BorderLayout.CENTER );
      getContentPane().add( panel, BorderLayout.SOUTH );

      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      setBounds(100, 100, 400, 300);
      setVisible(true);
   }

/*  The TreeModelListener is implemented as an inner class.           */
/*  When the user removes a tree node, a TreeModelEvent is generated  */
/*  and sent to the treeNodesRemoved() method. This method uses the   */
/*  event to obtain a reference to the node that was removed, its     */
/*  parent node, and its index.  It then displays a confirm dialog,   */
/*  so the user can confirm the removal.  If the user does not        */
/*  confirm the the removal, the node is placed back inside the       */
/*  tree. The other methods declared in the TreeModelListener         */
/*  interface are not used, so they are implemented as stub methods.  */

   class TreeModelHandler implements TreeModelListener
   {
      public void treeNodesRemoved(TreeModelEvent event)
      {
         Object[] path = event.getPath();
         Object[] child = event.getChildren();
         int[] indices = event.getChildIndices();

         int confirm = 
             JOptionPane.showConfirmDialog(tree, "Confirm node deletion?");

         if  ( confirm != JOptionPane.YES_OPTION )
         {
            model.insertNodeInto( (MutableTreeNode)child[0], 
                                  (MutableTreeNode)path[path.length-1], 
                                  indices[0]);
         }
      }

      public void treeNodesChanged(TreeModelEvent event) {}
      public void treeNodesInserted(TreeModelEvent event) {}
      public void treeStructureChanged(TreeModelEvent event) {}
   }

/*  When the "remove" button is pressed, the selected node is removed  */
/*  from the tree.  This generates a TreeModelEvent that is sent to    */
/*  the TreeModelListener.                                             */

   public void actionPerformed(ActionEvent event)
   {
      DefaultMutableTreeNode node = 
               (DefaultMutableTreeNode)tree.getLastSelectedPathComponent();

      if ( !node.isRoot() )
      {
         model.removeNodeFromParent(node);
      }
   }

   public static void main(String args[]) 
   {
      TreeModelEventDemo demo = new TreeModelEventDemo();
   }
}