Using the new persistence mechanism in 1.4 doesn't seem to work on DefaultMutableTreeNode. Since it's possible to persist a panel with nested components, I would assume that the same thing should hold true for the relationships between tree nodes. Here's a sample program to demonstrate this:

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import java.beans.*;
import java.util.*;
import java.io.*;
import javax.swing.tree.*;

public class PersistTree {

    private XMLEncoder encoder;
    private XMLDecoder decoder;
    private DefaultMutableTreeNode root, node, temp;

    public static void main(String[] args) {
        new PersistTree();
    }

    public PersistTree() {
        try {
            encoder = new XMLEncoder(new BufferedOutputStream
                      (new FileOutputStream("tree.xml")));
        } catch(Exception e) {
            e.printStackTrace();
        }

        node = new DefaultMutableTreeNode();
        root = node;

        temp = new DefaultMutableTreeNode();
        node.add(temp);

        temp = new DefaultMutableTreeNode();
        node.add(temp);

        node = new DefaultMutableTreeNode();
        temp.add(node);

        System.out.println("Before encoding. Child count: " + root.getChildCount());

        encoder.writeObject(root);
        encoder.close();

        try {
            decoder = new XMLDecoder(new BufferedInputStream(
                      new FileInputStream("tree.xml")));
        } catch(Exception e) {
            e.printStackTrace();
        }

        root = (DefaultMutableTreeNode)decoder.readObject();
        System.out.println("After decoding. Child count: " + root.getChildCount());

        System.out.println();
    }
}

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###@###.### 2001-09-17
Swing Test Development