Android TCP Client/Server not passing messages properly (Only first received)

Question

I have created two android applications, a client and a server, utilizing TCP to communicate across devices. On the server, I have this code to listen for TCP communication:

private class StartServer implements Runnable {     
    public void run() {
            getState(); // This just refreshes the server state
            try {
                serverSocket = new ServerSocket(5000);
                appendLog("Server successfully listening ["+getLocalIpAddress() + ":5000]"); //appendLog function just uses runOnUiThread() to update the log textview
            } catch (IOException e) {
                appendLog("Could not listen on port: 5000");
                //System.exit(-1);
            }
            BufferedReader in = null;
            BufferedWriter out = null;
            String input = null;


            try {
                clientSocket = serverSocket.accept(); 
                in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                out = new BufferedWriter(new OutputStreamWriter(clientSocket.getOutputStream()));

                while (serverState) { //variable set by our getState() function

                    input = in.readLine();
                    appendLog("Received: " + input);
                    this.gotMessage(out, input);
                }
                in.close();
                out.close();
            } catch (IOException e) {
                //appendLog(e.toString());
                appendLog("Accept failed: 5000");
                //System.exit(-1);
            }
    }

Which calls this function to actually parse the recieved messages:

private void gotMessage(BufferedWriter output, String msg) {
        if (msg != null) {
            String sString = msg;
            int to_do = 0;


            if (msg.matches("^(?i)(exit|quit|close)$")) {
                appendLog("Exiting");
                sString = "Goodbye";
                to_do=1;
            } else if (msg.matches("^(?i)(launch|run|open)\\s(.+)")) {
                appendLog("Launching application");
                sString = "Launching application";
            } else if (msg.matches("^(?i)(turn off|server off|deactivate)$")) {
                appendLog("Turning off server due to remote command.");
                sString = "Turning off...";
                to_do=2;
            } else if (msg.matches("^(?i)(restart|reboot)$")) {
                appendLog("Resetting server");
                sString = "Rebooting now...";
                to_do=3;
            }


            try {
                output.write("S: " + sString);
                output.newLine();
                output.flush();
            } catch (IOException e) {
                appendLog("Cannot parse message");
            }


            switch(to_do) {
                case 0:
                    break;
                case 1:
                    System.exit(0);
                    break;
                case 2:
                    serverOff();
                    break;
                case 3:
                    serverOff();
                    serverOn();
                    break;
                default:
                    break;
            }
        }
    }
}

The thread itself for the server is started using Thread t = new Thread(new StartServer()); t.start() Thread t = new Thread(new StartServer()); t.start() . And to the best of my knowledge, this works fine. I can open up a terminal and telnet to the IP and port, and pass communication back and forth without error. But when I try to do the same from the client code below. I only get the first message, and anything else I pass in just dissappears into the void.

public void sendToServer(View v) {
    try {
        String ip = ((TextView)findViewById(R.id.ip_box)).getText().toString(); //User entered IP address
        String to_send = ((EditText)findViewById(R.id.send_to_server)).getText().toString(); //User entered text to send
        this.s = new Socket(ip, 5000);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
        appendLog("Sending: " + to_send);
        out.write(to_send);
                    out.newLine();
        out.close();
    } catch (Exception e) {
        Log.d("error", e.toString());
    }
}

Answer 1

Do you have line-end character in your to_send string? if no, just add out.newLine() to your client code:

appendLog("Sending: " + to_send);
out.write(to_send);
out.newLine();

You server code should look like this to support multiple clients:

// main server loop
while (serverIsActive) {
    clientSocket = serverSocket.accept(); 
    // spawn new thread for each client
    ClientThread ct = new ClientThread(clientSocket);
    ct.start();
}

ClientThread should work with client socket and have its own loop for reading lines. It should stop as soon as client closes socket:

class ClientThread {
    ...
    public void run() {
        ....
        while ((inputLine = in.readLine()) != null) {
            // process client message
        }
        in.close();
    }
}