Easiest way to clone a whole JTree/TreeModel?

Question

Do i really have to implement the deep-clone myself or are there any library methods to get a deep clone of an JTree or it's TreeModel?

Answer 1

public IndigoMutableTreeNode cloneNode(IndigoMutableTreeNode node){
		IndigoMutableTreeNode newNode = new IndigoMutableTreeNode(node.getUserObject());
        for(int iChildren=node.getChildCount(), i=0;i<iChildren; i++){
                newNode.add((IndigoMutableTreeNode)cloneNode((IndigoMutableTreeNode)node.getChildAt(i) ) );
        }
        return newNode;
    }

Just pass the root node and get the complete different root node and pass it to a new model of new tree.

Answer 2

As said by @SteveKuo, why do you need to clone a TreeModel? TreeModel can be shared amongst different instances of JTree.

Here is a sample demo of two JTree's sharing the same model. Alternatively, you could create twice the same TreeModel:

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;

public class Test2JTree {

    private void initUI() {
        final JFrame frame = new JFrame(Test2JTree.class.getSimpleName());
        final DefaultTreeModel model = getTreeModel();
        final JTree tree1 = new JTree(model);
        final JTree tree2 = new JTree(model);
        frame.add(new JScrollPane(tree1), BorderLayout.WEST);
        frame.add(new JScrollPane(tree2), BorderLayout.EAST);
        frame.pack();
        frame.setSize(frame.getWidth() + 50, frame.getHeight() + 140);
        frame.setVisible(true);
        Timer t = new Timer(2000, new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {
                DefaultMutableTreeNode root = (DefaultMutableTreeNode) model.getRoot();
                root.add(new DefaultMutableTreeNode("A new node"));
                model.nodesWereInserted(root, new int[] { root.getChildCount() - 1 });
                tree1.expandRow(0);
                tree2.expandRow(0);
                frame.revalidate();
            }
        });
        t.start();
    }

    private DefaultTreeModel getTreeModel() {
        return new DefaultTreeModel(new DefaultMutableTreeNode("Root object"));
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                new Test2JTree().initUI();
            }
        });
    }
}

Answer 3

Why do you need to clone both JTree and TreeModel. JTree is the view, which displays whatever the backing TreeModel represents. If want to create a second identical tree, then you'd copy/clone the tree model, and create a new JTree which points to the copied TreeModel.