treeselectiondemo.java

来自「《java事件处理指南》一书的代码,好东西」· Java 代码 · 共 89 行

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

public class TreeSelectionDemo extends JFrame 
                               implements TreeSelectionListener
{
   private JTree tree;
   private JTextField jtf;

   public TreeSelectionDemo() 
   {
/*  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.   */

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

/*  A JTree object is created using the previously created tree model.  */
/*  The JTree registers a TreeSelectionListener.                        */

      tree = new JTree(dtm);
      tree.setShowsRootHandles(true);
      tree.expandRow(1);
      tree.getSelectionModel().setSelectionMode(
                  TreeSelectionModel.SINGLE_TREE_SELECTION);
      tree.addTreeSelectionListener(this);

      jtf = new JTextField(20);
      jtf.setEditable(false);

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

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

/*  The TreeSeletionDemo class serves as the TreeSelectionListener,   */
/*  so it provides an implementation of the valueChanged() method.    */
/*  When the user selects a node, a TreeSelectionEvent is generated   */
/*  and sent to the valueChanged() method.  The identity of the       */
/*  currently selected node is printed inside a JTextField.           */

   public void valueChanged(TreeSelectionEvent event) 
   {
      TreePath path = event.getPath();
      jtf.setText("Current selection is "+path.getLastPathComponent());
   }

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