TCP for Client ANDROID

public class MyTCP extends AsyncTask<Void, String, Void> {

        String dstAddress;
        int dstPort;
        String response = "";
        boolean isFirst = true;

        MyTCP(String addr, int port) {
            dstAddress = addr;
            dstPort = port;
        }
        @Override
        protected  void onPreExecute(){
            textResponse.setText("Hello bạn!");
        }
        @Override
        protected Void doInBackground(Void... arg0) {

            Socket socket = null;
            try {
                socket = new Socket(dstAddress, dstPort);

                //SystemClock.sleep(5000);

                BufferedReader buff = new BufferedReader(new
                        InputStreamReader(socket.getInputStream()));
                String inputLine= buff.readLine();
                while(inputLine != null) {
                    //khi gọi hàm này thì onProgressUpdate sẽ thực thi
                    publishProgress(inputLine);
                    inputLine= buff.readLine();

                }
            } catch (UnknownHostException e) {
                e.printStackTrace();
                response = "UnknownHostException: " + e.toString();
            } catch (IOException e) {
                e.printStackTrace();
                response = "IOException: " + e.toString();
            } finally {
                if (socket != null) {
                    try {
                        socket.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }


            }
            // SystemClock.sleep(5000);
            //}

            return  null;
        }
// Cập nhật giao diện ở đây
        @Override
        protected void onProgressUpdate(String... values) {
            // TODO Auto-generated method stub
            super.onProgressUpdate(values);
                textResponse.append("\n" + values[0]);
            if(response != "") {
                textResponse.setText(response);
                response ="";
            }
        }
// Hàm này tự động gọi sau khi thực thi xong hết
        @Override
        protected void onPostExecute(Void result) {
            super.onPostExecute(result);
            isFirst = true;
            //textResponse.append("\n" + response);
        }

    }