How can I select multiple nodes by standard

Question

I want to ask how can I modify this example code to enable multiple selection, say if I select node1, system out display node1, then ctr+node2 selection. system out display node1&node2.
The code below, only display node1, then when I do ctr+node2 selection, system out still display node1.
I am quite new to JTree, so, please if there is anyone can give a solution?
Thanks
* 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 javax.swing.JEditorPane;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.UIManager;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeSelectionModel;
import javax.swing.event.TreeSelectionEvent;
import javax.swing.event.TreeSelectionListener;
import java.net.URL;
import java.io.IOException;
import java.awt.Dimension;
import java.awt.GridLayout;
public class TreeDemo extends JPanel
                      implements TreeSelectionListener {
    private JEditorPane htmlPane;
    private JTree tree;
    private URL helpURL;
    private static boolean DEBUG = false;
    //Optionally play with line styles.  Possible values are
//  "Angled" (the default), "Horizontal", and "None".
    private static boolean playWithLineStyle = false;
    private static String lineStyle = "Horizontal";
    //Optionally set the look and feel.
    private static boolean useSystemLookAndFeel = false;
    public TreeDemo() {
        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.DISCONTIGUOUS_TREE_SELECTION);---->Cause problem, when press Ctr to multiple select, always the first selected node is returned, which is shown in System out
        //Listen for when the selection changes.
        tree.addTreeSelectionListener(this);
        if (playWithLineStyle) {
            System.out.println("line style = " + lineStyle);
            tree.putClientProperty("JTree.lineStyle", lineStyle);
        //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();
        System.out.print("\nMy selection node is"+nodeInfo.toString());
        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 = TreeDemo.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 = TreeDemo.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);
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
    private static void createAndShowGUI() {
        if (useSystemLookAndFeel) {
            try {
                UIManager.setLookAndFeel(
                    UIManager.getSystemLookAndFeelClassName());
            } catch (Exception e) {
                System.err.println("Couldn't use system look and feel.");
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);
        //Create and set up the window.
        JFrame frame = new JFrame("TreeDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        //Create and set up the content pane.
        TreeDemo newContentPane = new TreeDemo();
        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();
}

Answer 1

you can use the method getSelectionPaths() in the class JTree. It will return an array of all the TreePaths you have selected. Then on each of the TreePath you got use the method getLastPathComponent() to get the nodes which you have selected.
Hope this solves your problem.