Thread Interaction

Question

I am writing a server - client program to transfer some data. First the main listens for a socket connection (main thread)
while (listening) new ServerComm(serverSocket.accept()).start();The class ServerComm(socket) is the second thread, it also implements an interface called PacketReader:
public interface PacketReader {
     public void processPacket(CommPacket packet);
public class ServerComm extends Thread implements PacketReader {
    private Socket socket = null;
    private CommTxRx comm = null;
    private boolean ack = false;
    private int status = 0x00;
    public ServerComm(Socket socket) {
      super("ServerComm");
      this.socket = socket;
    public void run() {
        comm = new CommTxRx(socket,this); comm.start();
        synchronized (this) {
             while (status != DONE || status != ABORT) {
                  try { wait(400);
                    } catch (InterruptedException e) { status = ABORT; }
          comm.close();
     public void processPacket(CommPacket packet) {
          switch (packet.cmd) {
            case CommDef.ACK: ack = true;
}CommTxRx actually does the reading and writing to the socket, and it is also a thread. It calls processPacket() when it recieves a new data packet
public class CommTxRx extends Thread {
     private Socket socket = null;
    private ObjectInputStream in = null;
    private ObjectOutputStream out = null;
    private PacketReader reader = null;
    private boolean streamOk = false;
    public boolean abort = false;
    public boolean pause = false;
    public CommTxRx(Socket socket, PacketReader reader) {
      this.socket = socket; this.reader = reader;
    public void run () {
         try {
            in = new ObjectInputStream(socket.getInputStream());
          out = new ObjectOutputStream(socket.getOutputStream());
         } catch (IOException e) {
          System.err.println("Stream Setup Error");
          streamOk = false;
          return;
         streamOk = true;
         synchronized(this) {
            while(streamOk) {
             try { this.wait(20); } catch (InterruptedException e) {
                      if (abort) close();
             try {
               if (in.available() != 0 && reader != null && !pause ) {
                    reader.processPacket(read());
           } catch (IOException e) { System.out.println("Read err"); }
             catch (ClassNotFoundException n) {System.out.println("Read err CNF");}
    public CommPacket read() throws IOException, ClassNotFoundException  {
        if (!streamOk) return null;
        return (CommPacket) in.readObject();
    }Here is my question, is this actually going to work, calling the processPacket inside the ServerComm thread from the CommTxRx thread, and does the CommRxTx thread suspend until the code in the ServerComm thread completes. What I would like to do is when a packet arrives and is processed by processPacket, it sends a reply and then waits until an ack packet is received, that would mean a second instance of processPacket would have to be launched to change the ack boolean, that would be in a wait() loop in the first call to processPacket. Am I going to have to setup every processPacket as a thread also in order to make that happen or because I already have two threads running is that going to work. I have not written the code to do that yet, I would like to find out if it is going to work before I get that far.

Answer 1

          while(streamOk) {
          try { this.wait(20); } catch (InterruptedException e) {Pointless. Remove.
               if (in.available() != 0 && reader != null && !pause ) {
                    reader.processPacket(read());Pointless. Remove. Just block in the readObject() method. If you want to poll, set a short read timeout.
I don't see the need for this class & thread at all, it should all be folded into the previous one.