A binary tree node serializer

Find below a binary tree node serializer:

import org.junit.Test;

import java.io.*;

public class NodeSerializer {
    private static final char NULL_CHAR = '\0';

    private static class Node {
        int data;
        Node left;
        Node right;

        void print() {
            System.out.println(data);
        }

        static void serialize(Node n, ObjectOutputStream into) throws IOException {
            if (n == null) {
                into.writeInt(NULL_CHAR);
                return;
            }
            into.writeInt(n.data);
            //into.write(DELIMITER);
            serialize(n.left, into);
            //into.write(DELIMITER);
            serialize(n.right, into);
        }

        static Node deserialize(ObjectInputStream from) throws IOException {
            int read = from.readInt();
            if (read == NULL_CHAR) {
                return null;
            }
            Node n = new Node();
            n.data = read;
            n.left = deserialize(from);
            n.right = deserialize(from);
            return n;
        }
    }

    @Test
    public void testNodeSerializer() throws IOException {
        Node n = new Node();
        n.data = 100;
        n.left = new Node();
        n.left.data = 200;
        n.left.left = null;
        n.left.right = null;
        n.right = new Node();
        n.right.left = null;
        n.right.data = 500;
        n.right.right = null;

        ByteArrayOutputStream baos;
        ObjectOutputStream os = new ObjectOutputStream(baos = new ByteArrayOutputStream(100));
        Node.serialize(n, os);
        os.flush();
        //String s = os.toString();


        ObjectInputStream byteArrayInputStream = new ObjectInputStream(new ByteArrayInputStream(baos.toByteArray()));

        Node node = Node.deserialize(byteArrayInputStream);

        node.print();
        node.left.print();
        node.right.print();

    }
}