//file: PartsTree.java
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

public class PartsTree {
  public static void main(String[] args) {
    // create a hierarchy of nodes
    MutableTreeNode root = new DefaultMutableTreeNode("Parts");
    MutableTreeNode beams = new DefaultMutableTreeNode("Beams");
    MutableTreeNode gears = new DefaultMutableTreeNode("Gears");
    root.insert(beams, 0);
    root.insert(gears, 1);
    beams.insert(new DefaultMutableTreeNode("1x4 black"), 0);
    beams.insert(new DefaultMutableTreeNode("1x6 black"), 1);
    beams.insert(new DefaultMutableTreeNode("1x8 black"), 2);
    beams.insert(new DefaultMutableTreeNode("1x12 black"), 3);
    gears.insert(new DefaultMutableTreeNode("8t"), 0);
    gears.insert(new DefaultMutableTreeNode("24t"), 1);
    gears.insert(new DefaultMutableTreeNode("40t"), 2);
    gears.insert(new DefaultMutableTreeNode("worm"), 3);
    gears.insert(new DefaultMutableTreeNode("crown"), 4);

    // create a JFrame to hold the tree
    JFrame f = new JFrame("PartsTree v1.0");
    f.addWindowListener(new WindowAdapter(  ) {
      public void windowClosing(WindowEvent e) { System.exit(0); }
    });
    f.setSize(200, 200);
    f.setLocation(200, 200);

    // create the JTree
    final DefaultTreeModel model = new DefaultTreeModel(root);
    final JTree tree = new JTree(model);

    // create a text field and button to modify the data model
    final JTextField nameField = new JTextField("16t");
    final JButton button = new JButton("Add a part");
    button.setEnabled(false);
    button.addActionListener(new ActionListener(  ) {
      public void actionPerformed(ActionEvent e) {
        TreePath tp = tree.getSelectionPath(  );
        MutableTreeNode insertNode =
            (MutableTreeNode)tp.getLastPathComponent(  );
        int insertIndex = 0;
        if (insertNode.getParent(  ) != null) {
          MutableTreeNode parent =
              (MutableTreeNode)insertNode.getParent(  );
          insertIndex = parent.getIndex(insertNode) + 1;
          insertNode = parent;
        }
        MutableTreeNode node =
            new DefaultMutableTreeNode(nameField.getText(  ));
        model.insertNodeInto(node, insertNode, insertIndex);
      }
    });
    JPanel addPanel = new JPanel(new GridLayout(2, 1));
    addPanel.add(nameField);
    addPanel.add(button);

    // listen for selections
    tree.addTreeSelectionListener(new TreeSelectionListener(  ) {
      public void valueChanged(TreeSelectionEvent e) {
        TreePath tp = e.getNewLeadSelectionPath(  );
        button.setEnabled(tp != null);
      }
    });

    // put it all together
    f.getContentPane(  ).add(new JScrollPane(tree));
    f.getContentPane(  ).add(addPanel, BorderLayout.SOUTH);
    f.setVisible(true);
  }
}