@Override
 public void onChanged(int position, int count) {
   Toast.makeText(getActivity(), "SortedList.Callback.onChanged", Toast.LENGTH_SHORT)
       .show();
   if (adapter != null) adapter.notifyItemRangeChanged(position, count);
 }
 @Override
 public void onMoved(int fromPosition, int toPosition) {
   Toast.makeText(getActivity(), "SortedList.Callback.onMoved", Toast.LENGTH_SHORT)
       .show();
   if (adapter != null) adapter.notifyItemMoved(fromPosition, toPosition);
 }