RMI related NotSerializableException problem

Question

Hi,
I am attempting to write a distributed chess player program. I've written a ChessServer class that all clients register with before they can play (which keeps track of how many clients are connected). Each clients creates an instance of a ChessServerListener which they add to the ChessServer's vector of listeners via a remote call to the method 'addChessServerListener(ChessServerListener listener)' in the ChessServer class. Everytime a new Client registers with the server, an event method is fired which notifies all listeners.
My client uses the following code to create the listener and add it to the server's vector of listeners:
chessServerListener = new ChessServerListener() {
public void clientListValueChanged() {
System.out.println("client list value changed");
//The following results in a RemoteException:
chessServer.addChessServerListener(chessServerListener);
The exception is as follows:
trouble: RemoteException
java.rmi.MarshalException: error marshalling arguments; nested exception is:
          java.io.NotSerializableException: frontend.IBoard$12
          at sun.rmi.server.UnicastRef.invoke(Uknown Source)
          at frontend.RMI.ChessServerImpl_Stub.addChessServerListener(Uknown Source)
          at frontend.IBoard.connectToChessServer(IBoard.java:430)
I have done a million Google searches trying to sort this out, and I think it might have something to do with the code I use to start up my ChessServer, which is as follows:
UnicastRemoteObject.exportObject(this,REG_PORT);
reg = LocateRegistry.createRegistry(REG_PORT);
reg.rebind(SERVER_NAME, this);
Can anyone help me? I can't continue with my project until I solve this!
Thanks in advance.

Answer 1

Anonymous classes that you create from an interface implement only that interface; they are not Serializable. You need to declare the listener as a named local class:class LocalClass implements ChessServerListener, Serializable {
    public void clientListValueChanged() {
        System.out.println("client list value changed");
chessServerListener = new LocalClass();
chessServer.addChessServerListener(chessServerListener);
...