/* * This code is based on an example provided by Richard Stanford,  * a tutorial reader. */import java.awt.GridLayout;import java.awt.Toolkit;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTree;import javax.swing.tree.DefaultMutableTreeNode;import javax.swing.tree.DefaultTreeModel;import javax.swing.tree.MutableTreeNode;import javax.swing.tree.TreePath;import javax.swing.tree.TreeSelectionModel;import javax.swing.event.TreeModelEvent;import javax.swing.event.TreeModelListener;public class DynamicTree extends JPanel {    protected DefaultMutableTreeNode rootNode;    protected DefaultTreeModel treeModel;    protected JTree tree;    private Toolkit toolkit = Toolkit.getDefaultToolkit();    public DynamicTree() {        super(new GridLayout(1,0));                rootNode = new DefaultMutableTreeNode("Root Node");        treeModel = new DefaultTreeModel(rootNode);        treeModel.addTreeModelListener(new MyTreeModelListener());        tree = new JTree(treeModel);        tree.setEditable(true);        tree.getSelectionModel().setSelectionMode                (TreeSelectionModel.SINGLE_TREE_SELECTION);        tree.setShowsRootHandles(true);        JScrollPane scrollPane = new JScrollPane(tree);        add(scrollPane);    }    /** Remove all nodes except the root node. */    public void clear() {        rootNode.removeAllChildren();        treeModel.reload();    }    /** Remove the currently selected node. */    public void removeCurrentNode() {        TreePath currentSelection = tree.getSelectionPath();        if (currentSelection != null) {            DefaultMutableTreeNode currentNode = (DefaultMutableTreeNode)                         (currentSelection.getLastPathComponent());            MutableTreeNode parent = (MutableTreeNode)(currentNode.getParent());            if (parent != null) {                treeModel.removeNodeFromParent(currentNode);                return;            }        }         // Either there was no selection, or the root was selected.        toolkit.beep();    }    /** Add child to the currently selected node. */    public DefaultMutableTreeNode addObject(Object child) {        DefaultMutableTreeNode parentNode = null;        TreePath parentPath = tree.getSelectionPath();        if (parentPath == null) {            parentNode = rootNode;        } else {            parentNode = (DefaultMutableTreeNode)                         (parentPath.getLastPathComponent());        }        return addObject(parentNode, child, true);    }    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,                                            Object child) {        return addObject(parent, child, false);    }    public DefaultMutableTreeNode addObject(DefaultMutableTreeNode parent,                                            Object child,                                             boolean shouldBeVisible) {        DefaultMutableTreeNode childNode =                 new DefaultMutableTreeNode(child);        if (parent == null) {            parent = rootNode;        }        treeModel.insertNodeInto(childNode, parent,                                  parent.getChildCount());        //Make sure the user can see the lovely new node.        if (shouldBeVisible) {            tree.scrollPathToVisible(new TreePath(childNode.getPath()));        }        return childNode;    }    class MyTreeModelListener implements TreeModelListener {        public void treeNodesChanged(TreeModelEvent e) {            DefaultMutableTreeNode node;            node = (DefaultMutableTreeNode)                     (e.getTreePath().getLastPathComponent());            /*             * If the event lists children, then the changed             * node is the child of the node we've already             * gotten.  Otherwise, the changed node and the             * specified node are the same.             */            try {                int index = e.getChildIndices()[0];                node = (DefaultMutableTreeNode)                       (node.getChildAt(index));            } catch (NullPointerException exc) {}            System.out.println("The user has finished editing the node.");            System.out.println("New value: " + node.getUserObject());        }        public void treeNodesInserted(TreeModelEvent e) {        }        public void treeNodesRemoved(TreeModelEvent e) {        }        public void treeStructureChanged(TreeModelEvent e) {        }    }}