If object is send twice BUT CHANGED server doesn't respond properly

Question

It seams there is a bug in Java 6 Serialization:
Instantiate object x.
Send it to the server and check the values.
Change your client-side instance.
Resend and check the values again.
The server still shows the old values.
To prove this is wrote a little code example:
package testserializablebug;
import java.io.Serializable;
public class SharedObject implements Serializable {
    private String s;
    private int i;
    public SharedObject(String s, int i) {
        this.s = s;
        this.i = i;
    public void setI(int i) {
        this.i = i;
    @Override
    public String toString() {
        return s + "::" + i;
package testserializablebug;
import java.io.*;
import java.net.*;
public class ClientTest {
    DataInputStream in;
    ObjectOutputStream outO;
    public ClientTest() throws UnknownHostException, IOException {
        Socket socket = new Socket("localhost", 8000);
        in = new DataInputStream(socket.getInputStream());
        outO = new ObjectOutputStream(socket.getOutputStream());
        SharedObject so = new SharedObject("Text", 3);
        compareResponse(so);
        so.setI(5);
        compareResponse(so);
    private void compareResponse(SharedObject so) throws IOException {
        outO.writeObject(so);
        String actual = in.readUTF();
        String expected = so.toString();
        if (!actual.equals(expected)) {
            System.err.println("actual    " + actual);
            System.err.println("expected  " + expected);
        } else {
            System.out.println("OK        " + actual);
    public static void main(String[] args) throws UnknownHostException, IOException {
        new ClientTest();
package testserializablebug;
import java.io.*;
import java.net.*;
public class ServerTest {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Socket socket = new ServerSocket(8000).accept();
        ObjectInputStream inO = new ObjectInputStream(socket.getInputStream());
        DataOutputStream out = new DataOutputStream(socket.getOutputStream());
        SharedObject so1 = (SharedObject) inO.readObject();
        out.writeUTF(so1.toString());
        SharedObject so2 = (SharedObject) inO.readObject();
        out.writeUTF(so2.toString());
}Is this a bug, or am doing something wrong? Any ideas how i can bypass this bug (if it is)?

Answer 1

Is this a bug, or am doing something wrong? Any ideas how i can bypass this bug (if it is)?It isn't a bug. Read the javadoc for ObjectOutputStream, and for the reset method.
Kaj