I need to send Obj A but not Obj B which is referenced

Question

I'm having a problem with my serialization. Here's the set up:
The server creates an instance of Obj A and Obj B, which contain references to each other. I want to serialize Obj A and send it to the client, but not Obj B.
First I tried setting Obj A's reference of Obj B to null right before I sent it to the client, but I kept getting Null Pointer Exception.
Then I tried adding "transient" to Obj A's reference to Obj B, but now when Obj A appears on the client, the other fields are also blank. I assume this is because Java is ignoring Obj B and all of it's references including Obj A.
Is there some way to void Obj A's reference to Obj B right before it's sent, without nulling Obj B completely?
Thanks!
Matt

Answer 1

Then I tried adding "transient" to Obj A's reference to Obj B, but now when Obj A appears on the client, the other fields are also blank. I assume this is because Java is ignoring Obj B and all of it's references including Obj A.No. Something wrong here. Make objB transient in objA, and send objA. Everything else in objA should appear at the client. That's how I thought it should work, which is why I tried it in the first place...
Is there some way to void Obj A's reference to Obj B right before it's sent, without nulling Obj B completely? Setting objA.objB to null doesn't 'null objB completely'. It does nothing to the object B, only to A's reference to it.
That's what I thought, but it again it didn't work, so I guess I then wrongly assumed that it was nullying Obj B (which doesn't really make sense, and of course it's wrong).
Ok here's the object I serialize and send:
public class Info implements Serializable{
    Client clientInfo;
    String cmd;
    ArrayList<String> handleList = new ArrayList<String>();
    ArrayList<Territory> list = new ArrayList<Territory>();
some methods....Then there's the Client class, which is where the problem is (Obj A from my first post)
public class Client implements Serializable {
    public int ID;
    String handle;
    public ClientThread threadName;
    public int money;
    public ArrayList<Territory> ownTerrList = new ArrayList<Territory>();
    public ArrayList moveList = new ArrayList();
    public ArrayList attackList = new ArrayList();
    public ArrayList buildList = new ArrayList();
some methods....Then the ClientThread class (Obj B from my first post), which is what's causing the problems because I think it cannot be serialized because it's a thread, is that correct?
Notice that the Client class above contains a reference to ClientThread threadName, which is the corresponding instance/thread of the class below, which contains a reference to the Client class above, Client client (so Obj A has a reference to Obj B and Obj B has a reference to Obj A):
public  class ClientThread implements Runnable, Serializable{
        Client client;
        Socket connection;
        String msg;
        ObjectInputStream objIn;
        ObjectOutputStream objOut;
        Info courier = new Info();
        C2Server server = null;
        public ClientThread(Socket connection, C2Server server, int id){
            this.server = server;
            this.client = new Client();
            this.client.ID = id;
            this.connection = connection;
            this.client.threadName = this;
            server.addClient(client);
a run method...
some other methods....
       My normal procedure for sending the information across the network is:
1) Update the Client instance which is inside the Info instance, which is the object sent.
2)Send
Then I started getting errors and problems so I started doing this:
1)Update the Client instance which is inside the Info instance, which is the object sent.
2) Set the Client instance's reference to the ClientThread instance to null (threadName =null)
3) Send
When the Info instance "gets" to the other side and is deserialized, the String cmd and ArrayList handleList are intact, but the ArrayList list and ArrayList ownTerrList (inside the Client instance) are both empty. I know those ArrayLists are full before I send because I do a System.out.println on them and they print out correctly with objects for each of my threads. They are full on the server side, then empty on the client side, and I can't figure out what the problem is. What might cause some of the fields in an object to be deserialized incorrectly while others are fine?
Thanks.
Matt