@Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    ButterKnife.inject(this);

    ExitAppUtil.getInstance().addActivity(this);
  }
 @Override
 protected void onDestroy() {
   super.onDestroy();
   ExitAppUtil.getInstance().delActivity(this);
 }