/* * This code is based on an example provided by Richard Stanford,  * a tutorial reader. */import java.awt.BorderLayout;import java.awt.Dimension;import java.awt.GridLayout;import java.awt.event.ActionEvent;import java.awt.event.ActionListener;import javax.swing.JButton;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.tree.DefaultMutableTreeNode;public class DynamicTreeDemo extends JPanel                              implements ActionListener {    private int newNodeSuffix = 1;    private static String ADD_COMMAND = "add";    private static String REMOVE_COMMAND = "remove";    private static String CLEAR_COMMAND = "clear";        private DynamicTree treePanel;    public DynamicTreeDemo() {        super(new BorderLayout());                //Create the components.        treePanel = new DynamicTree();        populateTree(treePanel);        JButton addButton = new JButton("Add");        addButton.setActionCommand(ADD_COMMAND);        addButton.addActionListener(this);                JButton removeButton = new JButton("Remove");        removeButton.setActionCommand(REMOVE_COMMAND);        removeButton.addActionListener(this);                JButton clearButton = new JButton("Clear");        clearButton.setActionCommand(CLEAR_COMMAND);        clearButton.addActionListener(this);        //Lay everything out.        treePanel.setPreferredSize(new Dimension(300, 150));        add(treePanel, BorderLayout.CENTER);        JPanel panel = new JPanel(new GridLayout(0,1));        panel.add(addButton);        panel.add(removeButton);        panel.add(clearButton);        add(panel, BorderLayout.LINE_END);    }    public void populateTree(DynamicTree treePanel) {        String p1Name = new String("Parent 1");        String p2Name = new String("Parent 2");        String c1Name = new String("Child 1");        String c2Name = new String("Child 2");        DefaultMutableTreeNode p1, p2;        p1 = treePanel.addObject(null, p1Name);        p2 = treePanel.addObject(null, p2Name);        treePanel.addObject(p1, c1Name);        treePanel.addObject(p1, c2Name);        treePanel.addObject(p2, c1Name);        treePanel.addObject(p2, c2Name);    }        public void actionPerformed(ActionEvent e) {        String command = e.getActionCommand();                if (ADD_COMMAND.equals(command)) {            //Add button clicked            treePanel.addObject("New Node " + newNodeSuffix++);        } else if (REMOVE_COMMAND.equals(command)) {            //Remove button clicked            treePanel.removeCurrentNode();        } else if (CLEAR_COMMAND.equals(command)) {            //Clear button clicked.            treePanel.clear();        }    }    /**     * Create the GUI and show it.  For thread safety,     * this method should be invoked from the     * event-dispatching thread.     */    private static void createAndShowGUI() {        //Make sure we have nice window decorations.        JFrame.setDefaultLookAndFeelDecorated(true);        //Create and set up the window.        JFrame frame = new JFrame("DynamicTreeDemo");        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);        //Create and set up the content pane.        DynamicTreeDemo newContentPane = new DynamicTreeDemo();        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();            }        });    }}