exercise24_15.java

java程序设计 机械工业出版社 书籍代码

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

public class Exercise24_15 extends JApplet {
  // Create a combo box for choosing selection modes
  private JComboBox jcboSelectionMode = new JComboBox(new String[]{
    "CONTIGUOUS_TREE_SELECTION", "DISCONTIGUOUS_TREE_SELECTION",
    "SINGLE_TREE_SELECTION"});

  // Create two buttons
  private JButton jbtAdd = new JButton("Add Node");
  private JButton jbtRemove = new JButton("Remove Selected Node");

  // Declare two trees
  private JTree jTree1, jTree2;

  public Exercise24_15() {
    // Create the first tree
    DefaultMutableTreeNode root, europe, northAmerica, us;

    europe = new DefaultMutableTreeNode("Europe");
    europe.add(new DefaultMutableTreeNode("UK"));
    europe.add(new DefaultMutableTreeNode("Germany"));
    europe.add(new DefaultMutableTreeNode("France"));
    europe.add(new DefaultMutableTreeNode("Norway"));

    northAmerica = new DefaultMutableTreeNode("North America");
    us = new DefaultMutableTreeNode("US");
    us.add(new DefaultMutableTreeNode("California"));
    us.add(new DefaultMutableTreeNode("Texas"));
    us.add(new DefaultMutableTreeNode("New York"));
    us.add(new DefaultMutableTreeNode("Florida"));
    us.add(new DefaultMutableTreeNode("Illinois"));
    northAmerica.add(us);
    northAmerica.add(new DefaultMutableTreeNode("Canada"));

    root = new DefaultMutableTreeNode("World");
    root.add(europe);
    root.add(northAmerica);

    jcboSelectionMode.setSelectedIndex(1);

    JPanel p1 = new JPanel();
    p1.add(new JLabel("selectionMode"));
    p1.add(jcboSelectionMode);
    p1.add(jbtAdd);
    p1.add(jbtRemove);

    JPanel p2 = new JPanel();
    p2.setLayout(new GridLayout(1, 2));
    p2.add(new JScrollPane(jTree1 = new JTree(root)));
    p2.add(new JScrollPane(jTree2 =
                           new JTree(new DefaultTreeModel(root))));

    getContentPane().add(p1, BorderLayout.NORTH);
    getContentPane().add(p2, BorderLayout.CENTER);

    // Register listeners
    jcboSelectionMode.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        if (jcboSelectionMode.getSelectedItem().
            equals("CONTIGUOUS_TREE_SELECTION"))
          jTree1.getSelectionModel().setSelectionMode(
              TreeSelectionModel.CONTIGUOUS_TREE_SELECTION);
        else if (jcboSelectionMode.getSelectedItem().
                 equals("DISCONTIGUOUS_TREE_SELECTION"))
          jTree1.getSelectionModel().setSelectionMode(
              TreeSelectionModel.DISCONTIGUOUS_TREE_SELECTION);
        else
          jTree1.getSelectionModel().setSelectionMode(
              TreeSelectionModel.SINGLE_TREE_SELECTION);
      }
    });

    jTree1.addKeyListener(new KeyAdapter() {
       public void keyPressed(KeyEvent e) {
         if (e.getKeyCode() == KeyEvent.VK_INSERT)
           insertNewNode();
         else if (e.getKeyCode() == KeyEvent.VK_DELETE)
           deleteNode();
       }
    });

    jbtAdd.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        insertNewNode();
      }
    });

    jbtRemove.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        deleteNode();
      }
    });
  }

  private void insertNewNode() {
    DefaultMutableTreeNode parent = (DefaultMutableTreeNode)
        jTree1.getLastSelectedPathComponent();

    if (parent == null) {
      JOptionPane.showMessageDialog(null,
        "No node in the first tree is selected");
      return;
    }

    // Enter a new node
    String nodeName = JOptionPane.showInputDialog(
      null, "Enter a name for this new node", "Add a Child",
      JOptionPane.QUESTION_MESSAGE);

    // Insert the new node as a child of treeNode
    parent.add(new DefaultMutableTreeNode(nodeName));

    // Reload the model since a new tree node is added
    ((DefaultTreeModel)(jTree1.getModel())).reload();
    ((DefaultTreeModel)(jTree2.getModel())).reload();
  }

  private void deleteNode() {
    // Get all selected paths
    TreePath[] paths = jTree1.getSelectionPaths();

    if (paths == null) {
      JOptionPane.showMessageDialog(null,
                                    "No node in the left tree is selected");
      return;
    }

    // Remove all selected nodes
    for (int i = 0; i < paths.length; i++) {
      DefaultMutableTreeNode node = (DefaultMutableTreeNode)
          (paths[i].getLastPathComponent());

      if (node.isRoot()) {
        JOptionPane.showMessageDialog(null,
                                      "Cannot remove the root");
      }
      else
        node.removeFromParent();
    }

    // Reload the model since a new tree node is added
    ((DefaultTreeModel) (jTree1.getModel())).reload();
    ((DefaultTreeModel) (jTree2.getModel())).reload();
  }

  public static void main(String[] args) {
    Exercise24_15 applet = new Exercise24_15();
    JFrame frame = new JFrame();
    //EXIT_ON_CLOSE == 3
    frame.setDefaultCloseOperation(3);
    frame.setTitle("Exercise24_15");
    frame.getContentPane().add(applet, BorderLayout.CENTER);
    applet.init();
    applet.start();
    frame.setSize(650, 320);
    Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
    frame.setLocation((d.width - frame.getSize().width) / 2,
                      (d.height - frame.getSize().height) / 2);
    frame.setVisible(true);
  }
}