public class BackgroundWorker extends AsyncTask<String,Void,String> {
        Context context;
        AlertDialog alertDialog;
        BackgroundWorker (Context ctx) {
            context = ctx;
        }
        @Override
        protected String doInBackground(String... params) {
            String type = params[0];
            String register_url = "http://xxxxx/register.php";
            if (type.equals("register")) {
                try {
                    String username = params[1];
                    String password = params[2];
                    URL url = new URL(register_url);
                    HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                    httpURLConnection.setRequestMethod("POST");
                    httpURLConnection.setDoOutput(true);
                    httpURLConnection.setDoInput(true);
                    OutputStream outputStream = httpURLConnection.getOutputStream();
                    BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream, "UTF-8"));
                    String post_data = URLEncoder.encode("username", "UTF-8") + "=" + URLEncoder.encode(username, "UTF-8") + "&"
                            + URLEncoder.encode("password", "UTF-8") + "=" + URLEncoder.encode(password, "UTF-8");
                    bufferedWriter.write(post_data);
                    bufferedWriter.flush();
                    bufferedWriter.close();
                    outputStream.close();
                    InputStream inputStream = httpURLConnection.getInputStream();
                    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream, "iso-8859-1"));
                    String result = "";
                    String line = "";
                    while ((line = bufferedReader.readLine()) != null) {
                        result += line;
                    }
                    bufferedReader.close();
                    inputStream.close();
                    httpURLConnection.disconnect();
                    return result;
                } catch (MalformedURLException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            return null;
        }

   @Override
    protected void onPreExecute() {
        alertDialog = new AlertDialog.Builder(context).create();
        alertDialog.setTitle("Login Status");
    }

    @Override
    protected void onPostExecute(String result) {
        alertDialog.setMessage(result);
        alertDialog.show();
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }
}