Question

I have a BufferedReader, when I try to read it, it just hangs and doesn’t do anything, am I doing this right? I am using this in an AsyncTask.

• Edit: I have a tablet connected to the Wi-Fi, this connects to my computer which is broadcasting on 172.20.104.203 on port 5334, I can see when the thread starts, but nothing after that.

Here my code:

try {
       final BufferedReader in = new BufferedReader(
       new InputStreamReader(socket.getInputStream()));       
       String line = null;
       while ((line = in.readLine()) != null) {
          final String msg;
          msg = (line);
          Log.d("DeviceActivity", msg);
       }
    } catch (Exception e) {
        e.printStackTrace();
        Log.e("ClientAcivtity: Exception",
        String.valueOf(e));
    }

• EDIT
  I have all the right permissions or anything, I was doing this outside a AsyncTask and it worked perfectly, moved it because I didn’t want it in the main thread.

–Edit , here is the full code.

public class NetworkTask extends AsyncTask<Void, byte[], Boolean> {
        Socket nsocket; // Network Socket
        InputStream nis; // Network Input Stream
        OutputStream nos; // Network Output Stream
        private Handler handler = new Handler();

        Boolean connected = false;

        public static final int PORT = 5334;
        public String SERVERIP = "172.20.104.203";

        Socket socket;

        @Override
        protected void onPreExecute() {
            Log.i("AsyncTask", "onPreExecute");
            InetAddress serverAddr;
            try {
                serverAddr = InetAddress.getByName(SERVERIP);
                socket = new Socket(serverAddr, PORT);
                connected = true;
            } catch (UnknownHostException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            }
        }

        @Override
        protected Boolean doInBackground(Void... params) { // This runs on a
                                                            // different thread
            boolean result = false;

            try {

                Log.d("ClientActivity", "C: Connecting...");
                if (socket != null) {
                    int cont = 1;
                    while (cont == 1) {
                        try {
                            Log.d("ClientActivity", "C: Sending command.");
                            PrintWriter out = new PrintWriter(
                                    new BufferedWriter(new OutputStreamWriter(
                                            socket.getOutputStream())), true);
                            // where you issue the commands
                            out.println("getPos");
                            Log.d("ClientActivity", "C: Sent " + "getPos");

                        } catch (Exception e) {
                            Log.e("ClientAcivtity: Exception",
                                    String.valueOf(e));
                        }
                        try {
                            final BufferedReader in = new BufferedReader(
                                    new InputStreamReader(
                                            socket.getInputStream()));
                            String line = null;
                            while ((line = in.readLine()) != null) {
                                final String msg;
                                msg = (line);
                                Log.d("DeviceActivity", msg);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            Log.e("ClientAcivtity: Exception",
                                    String.valueOf(e));
                        }
                        cont--;
                    }

                    Log.d("ClientActivity", "C: Closed.");
                }
            } catch (Exception e) {
                Log.e("ClientAcivtity: Exception", String.valueOf(e));
            }

            return result;
        }

        @Override
        protected void onProgressUpdate(byte[]... values) {
            if (values.length > 0) {
                Log.i("AsyncTask", "onProgressUpdate: " + values[0].length
                        + " bytes received.");
            }
        }

        @Override
        protected void onCancelled() {
            Log.i("AsyncTask", "Cancelled.");
        }

        @Override
        protected void onPostExecute(Boolean result) {
            if (socket != null) {
                if (connected) {
                    if (result) {
                        Log.i("AsyncTask",
                                "onPostExecute: Completed with an Error.");
                        try {
                            socket.close();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    } else {
                        Log.i("AsyncTask", "onPostExecute: Completed.");
                        try {
                            socket.close();
                        } catch (IOException e) {
                            // TODO Auto-generated catch block
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
    }

Answer 1

My guess is that when you write out the command “getPos” the underlying BufferedWriter is not actually sending the data out on the line (you should verify this with tcpdump/wireshark). If this is the case, the server doesn’t responsed to the readLine(), since it never got a command. To verify this claim, add out.flush(); after out.println("getPos");

Really, tcpdump will probably give you a better answer then anyone on the forums.

Also see http://developer.android.com/reference/java/io/BufferedWriter.html