@Override
 protected void onStart() {
   super.onStart();
   if (!twitter.isAuthorized()) {
     twitter.authorize();
   }
 }
 public boolean onOptionsItemSelected(MenuItem item) {
   switch (item.getItemId()) {
     case R.id.item_logout:
       twitter.logout();
       return true;
     default:
       return false;
   }
 }