class AuthenticatorTask extends AsyncTask<Void, Void, Integer> {
        String username;
        String password;
        Exception ex = null;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            EditText usernameEditText = (EditText) findViewById(R.id.edit_text_username);
            EditText passwordEditText = (EditText) findViewById(R.id.edit_text_password);
            username = usernameEditText.getText().toString();
            password = passwordEditText.getText().toString();

        }

        @Override
        protected Integer doInBackground(Void... voids) {
            int userId = -1;
            try {
                Authenticator auth = new Authenticator();
                userId = auth.getUserId(username, password);
            } catch (Exception e) {
                ex = e;
            }
            return userId;
        }

        @Override
        protected void onPostExecute(Integer userId) {
            super.onPostExecute(userId);
            if (ex != null) {
                Toast.makeText(SignInActivity.this, "Error!", Toast.LENGTH_SHORT).show();
                Log.e("SignInActivity", "Error during sign in.", ex);
                return;
            }

            if (userId == -1) {
                Toast.makeText(SignInActivity.this, "Invalid username or password!", Toast.LENGTH_SHORT).show();
            } else {
                QuickTexterApp.getInstance().setUserId(userId);
                startActivity(new Intent(SignInActivity.this, DashboardActivity.class));
                finish();
            }
        }
    }