Unable to receive data from Java TCP server

Question

On the server, when I get a new connection (serverSocket.accept()), I pass that connection socket to an instance of a class called ServerPlayer.java, which extends from a thread.

I also create an OutputObjectStream and an InputObjectStream and pass those to the new ServerPlayer instance, and then add the ServerPlayer instance to an ArrayList to keep track of them.

When I call start() on the new ServerPlayer, I have it write a byte (1).

I then have my client run a Listening thread which listens for incoming data from the TCP Server. However, I am not receiving the (1) I sent from the server. I'm not sure if the Server just isn't sending it properly or if the client isn't receiving it properly...

ServerPlayer.java:

    /**
     * ServerPlayer.java
     * Creates a new instance of a player on the server, gives it
     * an output and input stream, as well as the socket it came in on
     */
    package server;

    import java.io.IOException;
    import java.io.ObjectInputStream;
    import java.io.ObjectOutputStream;
    import java.net.Socket;
    import java.util.logging.Level;
    import java.util.logging.Logger;

    public class ServerPlayer extends Thread {
        UIServer ui;
        Socket socket;
        ObjectOutputStream os;
        ObjectInputStream is;


        int id = -1;
        ServerPlayer(Socket socket, ObjectOutputStream os, ObjectInputStream is, UIServer ui){
            this.socket = socket;
            this.os = os;
            this.is = is;
            this.ui = ui;
        }

        public void setID(int id){
            this.id = id;
        }

        public int getID(){
            return this.id;
        }

        public void run(){
            boolean keepGoing = true;
            System.out.println("SERVERPLAYER THREAD START");
            try {
                os.writeByte(1);
                System.out.println("sent byte 1 from server");
            } catch (IOException ex) {
                Logger.getLogger(ServerPlayer.class.getName()).log(Level.SEVERE, null, ex);
            }
            while(keepGoing){
                try{
                    Byte msg = is.readByte();
                    int mes_id = msg.intValue();
                    ui.console.println("SERV MESSAGE#: " + mes_id);

                } catch (IOException ex) {
                    Logger.getLogger(ServerPlayer.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        }
    }

ListenFromServer.Java:

    /*
     * ListenFromServer.java
     * Listens for incoming data from the TCP Server (this is on the client side)
     */
    package client;

    import java.io.IOException;
    import java.util.logging.Level;
    import java.util.logging.Logger;

    public class ListenFromServer extends Thread {
        TCPClient client;
        boolean isRunning = false;
        public ListenFromServer(TCPClient client){
            this.client = client;
        }
        public void run(){
            System.out.println("listen from server thread start");
            isRunning = true;
            while(isRunning){

                try {
                    Byte b = client.sInput.readByte();
                    client.ui.console.println("BYTE: " + b.intValue());
                } catch (IOException ex) {
                    Logger.getLogger(ListenFromServer.class.getName()).log(Level.SEVERE, null, ex);
                }

            }
        }
    }

Answer 1

Try to change to

os.writeByte(1);
os.flush();