Question

Just trying to get a handle on sockets. The server and client are running in two different programs.

They seem to be connecting fine to each other but the client will not properly send its output to the server. The server just hangs. Here’s the code:

Server:

  private ServerSocket serverSocket;
  private Socket client;

  public void run() throws Exception {
     serverSocket = new ServerSocket(20005);
     while(currentState == Game.State.NORMAL) {
      client = serverSocket.accept();
      PrintWriter out = new PrintWriter(client.getOutputStream(), true);
      BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
      String clientInput = in.readLine();

      // Takes the client input string and does some simple game logic that returns a Gson object
      Gson serverResponse = processInput(clientInput);
      out.write(serverResponse.toString());
      out.flush();
    }
  }

Client:

Socket clientSocket;

  void run() throws Exception {
    clientSocket = new Socket("192.168.0.24", 20005);
    PrintWriter out;
    BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

    // Print the state of the game - returns false if state is win or lose.
    while(printState()) {
      out = new PrintWriter(clientSocket.getOutputStream(), true);
      // This method just takes some input from the console
      String clientInput = getInput();

      out.write(clientInput);
      out.flush();

      String serverResponse = in.readLine();

      updateState(serverResponse);
    }
  }
}

There is some underlying game logic that is happening but it’s pretty minor and should be irrelevant. I imagine I am just misunderstanding something fundamental here.

Thanks all.

Answer 1

Make sure you send a newline character to match the in.readLine() statement in the Server.

out.write(clientInput + "\n");

The same applys when sending data from Server->Client.