@Override
 public void onNavigationDrawerItemSelected(int position) {
   // update the main content by replacing fragments
   FragmentManager fragmentManager = getSupportFragmentManager();
   switch (position) {
     case 2:
       fragmentManager
           .beginTransaction()
           .replace(R.id.container, NotificationFragment.newInstance(position + 1))
           .commit();
       break;
     case 3:
       fragmentManager
           .beginTransaction()
           .replace(R.id.container, InventoryFragment.newInstance(position + 1))
           .commit();
       break;
     default:
       fragmentManager
           .beginTransaction()
           .replace(R.id.container, HomeFragment.newInstance(position + 1))
           .commit();
       break;
   }
 }