Why not work? mAdapter.notifyItemChanged(mIndex);

Android Programming (3rd Edition) 10. Using Fragment Arguments
1

private void updateUI(){
CrimeLab crimeLab=CrimeLab.get(getActivity());
List crimes=crimeLab.getCrimes();
if(mAdapter==null){
mAdapter=new CrimeAdapter(crimes);
mCrimeRecyclerView.setAdapter(mAdapter);
}else {
Log.d(TAG, "updateUI: ");
mAdapter.notifyItemChanged(mIndex);//why not work?
}