Java, when calling readObject() on an ObjectOutputStream it is only returning one value

Question

I'm writing a server / client game. My client sends a message to the server and the server is supposed to distribute that message to all other clients connected to the server. The problem I'm having is that when I call ois.readObject() (where ois is the ObjectInputStream created from the ServerSocket accept() call) it only ever returns the very first value that I write to the corresponding ObjectOutputStream on the client side.

This is the code for the Thread my server creates for each client that connects.

@Override
public void run() {
    Iterator<ClientThread> itr = null;
    ClientThread ct = null;
    Object recObj = null;
    try {
        oos.writeObject(id);
        oos.flush();

        while(oos != null && ois != null) {
            recObj = ois.readObject();
            System.out.println(recObj);
            if(recObj instanceof Player) {
                System.out.println("[" + id + "] Recieved player from client.");

                player = (Player) recObj;
                Server.playerMap.put(player.getId(), player);

                if(player == null) {
                    System.out.println("Player " + player.getId() + " has joined the server.");
                }

                itr = Server.threadList.iterator();
                while(itr.hasNext()) {
                    ct = itr.next();
                    if(!(ct.id == this.id)) {
                        ct.oos.writeObject(recObj);
                        ct.oos.flush();
                        System.out.println("Sending " + (Player) recObj + " to client " + ct.id + "!");
                    } else {
                        System.out.println("Don't send stuff to " + ct.id + " or we get an infinite loop!");
                    }
                }
            } else {
                System.err.println("Recieved something other than a Player object.");
            }
        }
    } catch (IOException e) {
        System.err.println("[INFO] " + e.getLocalizedMessage());

    } catch (ClassNotFoundException e) {
        System.err.println(e.getLocalizedMessage());
        e.printStackTrace();
    }
    cleanup();
}

This code is for the Thread that each client creates.

@Override
public void run() {
    Object recObj = null;
    Player newPlayer = null;
    try {
        recObj = client.ois.readObject();
        if(recObj instanceof Integer) {
            client.player = new Player((Integer) recObj);
            client.playerMap.put(client.player.getId(), client.player);
        } else {
            System.err.println("First object recieved from server was not of type Integer.");
            System.err.println("No valid id has been set.");
        }

        while(client.ois != null) {
            recObj = client.ois.readObject();
            if(recObj instanceof Player) {
                newPlayer = (Player) recObj;
                System.out.println("Recieved " + newPlayer + "!");
                client.playerMap.put(newPlayer.getId(), newPlayer); 
            }
        }
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

P.S. I realize I don't need to flush the ObjectOutputStream but it was just an idea to test.

Not sure if the threading is good this way, I would enqueue the messages for a client in the thread handling that client, but it should basically work in your scenario as well. (hopefully you do not send a new player to a client which not yet has received its id). Your sending whie loop might be blocked by a client not reading, verify it with a println before and after write. — eckes

Krrose27 Krrose27 · Accepted Answer · 2012-05-05T01:36:01

1

votes

Call .reset on the ObjectOutputStream after each write.

Java, when calling readObject() on an ObjectOutputStream it is only returning one value

1 Answers