TreeSelectionListener and TreeSelectionEvent : TreeSelectionListener « Swing Event « Java Tutorial






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 * Copyright (c) 1995 - 2008 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Sun Microsystems nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/**
 * A 1.4 application that requires the following additional files:
 *   TreeDemoHelp.html
 *    arnold.html
 *    bloch.html
 *    chan.html
 *    jls.html
 *    swingtutorial.html
 *    tutorial.html
 *    tutorialcont.html
 *    vm.html
 */

import java.awt.Dimension;
import java.awt.GridLayout;
import java.io.IOException;
import java.net.URL;

import javax.swing.ImageIcon;
import javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTree;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.TreeSelectionModel;

public class TreeIconDemo extends JPanel implements TreeSelectionListener {
  private JEditorPane htmlPane;
  private JTree tree;
  private URL helpURL;
  private static boolean DEBUG = false;

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

    // Create the nodes.
    DefaultMutableTreeNode top = new DefaultMutableTreeNode("The Java Series");
    createNodes(top);

    // Create a tree that allows one selection at a time.
    tree = new JTree(top);
    tree.getSelectionModel().setSelectionMode(
        TreeSelectionModel.SINGLE_TREE_SELECTION);

    // Set the icon for leaf nodes.
    ImageIcon leafIcon = createImageIcon("images/middle.gif");
    if (leafIcon != null) {
      DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer();
      renderer.setLeafIcon(leafIcon);
      tree.setCellRenderer(renderer);
    } else {
      System.err.println("Leaf icon missing; using default.");
    }

    // Listen for when the selection changes.
    tree.addTreeSelectionListener(this);

    // Create the scroll pane and add the tree to it.
    JScrollPane treeView = new JScrollPane(tree);

    // Create the HTML viewing pane.
    htmlPane = new JEditorPane();
    htmlPane.setEditable(false);
    initHelp();
    JScrollPane htmlView = new JScrollPane(htmlPane);

    // Add the scroll panes to a split pane.
    JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT);
    splitPane.setTopComponent(treeView);
    splitPane.setBottomComponent(htmlView);

    Dimension minimumSize = new Dimension(100, 50);
    htmlView.setMinimumSize(minimumSize);
    treeView.setMinimumSize(minimumSize);
    splitPane.setDividerLocation(100); // XXX: ignored in some releases
    // of Swing. bug 4101306
    // workaround for bug 4101306:
    // treeView.setPreferredSize(new Dimension(100, 100));

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

    // Add the split pane to this panel.
    add(splitPane);
  }

  /** Required by TreeSelectionListener interface. */
  public void valueChanged(TreeSelectionEvent e) {
    DefaultMutableTreeNode node = (DefaultMutableTreeNode) tree
        .getLastSelectedPathComponent();

    if (node == null)
      return;

    Object nodeInfo = node.getUserObject();
    if (node.isLeaf()) {
      BookInfo book = (BookInfo) nodeInfo;
      displayURL(book.bookURL);
      if (DEBUG) {
        System.out.print(book.bookURL + ":  \n    ");
      }
    } else {
      displayURL(helpURL);
    }
    if (DEBUG) {
      System.out.println(nodeInfo.toString());
    }
  }

  private class BookInfo {
    public String bookName;
    public URL bookURL;

    public BookInfo(String book, String filename) {
      bookName = book;
      bookURL = TreeIconDemo.class.getResource(filename);
      if (bookURL == null) {
        System.err.println("Couldn't find file: " + filename);
      }
    }

    public String toString() {
      return bookName;
    }
  }

  private void initHelp() {
    String s = "TreeDemoHelp.html";
    helpURL = TreeIconDemo.class.getResource(s);
    if (helpURL == null) {
      System.err.println("Couldn't open help file: " + s);
    } else if (DEBUG) {
      System.out.println("Help URL is " + helpURL);
    }

    displayURL(helpURL);
  }

  private void displayURL(URL url) {
    try {
      if (url != null) {
        htmlPane.setPage(url);
      } else { // null url
        htmlPane.setText("File Not Found");
        if (DEBUG) {
          System.out.println("Attempted to display a null URL.");
        }
      }
    } catch (IOException e) {
      System.err.println("Attempted to read a bad URL: " + url);
    }
  }

  private void createNodes(DefaultMutableTreeNode top) {
    DefaultMutableTreeNode category = null;
    DefaultMutableTreeNode book = null;

    category = new DefaultMutableTreeNode("Books for Java Programmers");
    top.add(category);

    // original Tutorial
    book = new DefaultMutableTreeNode(new BookInfo(
        "The Java Tutorial: A Short Course on the Basics", "tutorial.html"));
    category.add(book);

    // Tutorial Continued
    book = new DefaultMutableTreeNode(
        new BookInfo("The Java Tutorial Continued: The Rest of the JDK",
            "tutorialcont.html"));
    category.add(book);

    // JFC Swing Tutorial
    book = new DefaultMutableTreeNode(new BookInfo(
        "The JFC Swing Tutorial: A Guide to Constructing GUIs",
        "swingtutorial.html"));
    category.add(book);

    // Bloch
    book = new DefaultMutableTreeNode(new BookInfo(
        "Effective Java Programming Language Guide", "bloch.html"));
    category.add(book);

    // Arnold/Gosling
    book = new DefaultMutableTreeNode(new BookInfo(
        "The Java Programming Language", "arnold.html"));
    category.add(book);

    // Chan
    book = new DefaultMutableTreeNode(new BookInfo(
        "The Java Developers Almanac", "chan.html"));
    category.add(book);

    category = new DefaultMutableTreeNode("Books for Java Implementers");
    top.add(category);

    // VM
    book = new DefaultMutableTreeNode(new BookInfo(
        "The Java Virtual Machine Specification", "vm.html"));
    category.add(book);

    // Language Spec
    book = new DefaultMutableTreeNode(new BookInfo(
        "The Java Language Specification", "jls.html"));
    category.add(book);
  }

  /** Returns an ImageIcon, or null if the path was invalid. */
  protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = TreeIconDemo.class.getResource(path);
    if (imgURL != null) {
      return new ImageIcon(imgURL);
    } else {
      System.err.println("Couldn't find file: " + path);
      return null;
    }
  }

  /**
   * Create the GUI and show it. For thread safety, this method should be
   * invoked from the event-dispatching thread.
   */
  private static void createAndShowGUI() {
    // Create and set up the window.
    JFrame frame = new JFrame("TreeIconDemo");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    // Create and set up the content pane.
    TreeIconDemo newContentPane = new TreeIconDemo();
    newContentPane.setOpaque(true); // content panes must be opaque
    frame.setContentPane(newContentPane);

    // Display the window.
    frame.pack();
    frame.setVisible(true);
  }

  public static void main(String[] args) {
    // Schedule a job for the event-dispatching thread:
    // creating and showing this application's GUI.
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        createAndShowGUI();
      }
    });
  }
}








15.38.TreeSelectionListener
15.38.1.How to Write a Tree Selection ListenerHow to Write a Tree Selection Listener
15.38.2.Add nodes to a tree with tree node selection listener
15.38.3.TreeSelectionEvent.getNewLeadSelectionPath().getLastPathComponent()
15.38.4.implements TreeSelectionListener
15.38.5.TreeSelectionListener and TreeSelectionEvent