How to get inverted Recycleview position?

Question

I’m with a recycleview q takes the data from a database ( I’m using Sugar ORM ) and reversed the order because I wanted from the newest to the oldest, but to delete I need the position in the database, but I’m doing with Swipe, and it takes the position of adpater ( that is not the same of DB because it is inverted ), how to get the position so ?

  List<Notificacao> listnotificacoes = Notificacao.listAll(Notificacao.class);

        Log.d("igr","Lista de Notificaoes: " + listnotificacoes);

        LinearLayoutManager llm = new LinearLayoutManager(view.getContext());
        llm.setReverseLayout(true);
        llm.setStackFromEnd(true);
        mrecyclerView.setLayoutManager(llm);
        mAdapterNoti = new AdapterNotificacao(listnotificacoes);
        mrecyclerView.setAdapter(mAdapterNoti);

        ItemTouchHelper.SimpleCallback simpleItemTouchCallback = new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT) {
            @Override
            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
                return false;
            }

            @Override
            public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
                final int position = viewHolder.getAdapterPosition();
                Log.d("igr","posicao"+position);
                int posicaodb = position+1;
                Log.d("igr","posicaodb"+posicaodb);
                try{
                    try{
                        Notificacao notificacao = Notificacao.findById(Notificacao.class,posicaodb);
                        Log.d("igr",""+notificacao.getMensagem());
                    }catch (Exception e){
                        Log.d("igr","erro ao obter mensagem da notificao" + e);
                    }
                    //notificacao.delete();
                    //Log.d("igr","deletou  a notificao no BD");
                    //mAdapterNoti.notifyItemRemoved(position);

                }catch (Exception e){
                    Log.d("igr","Erro ao deletar a notificacao no DB" + e);

                }

            }
        };  

Code proposed by the Consortium:

@Override
public void onSwiped(RecyclerView.ViewHolder viewHolder, int swipeDir) {
    final int position = viewHolder.getAdapterPosition();
    Log.d("igr","posicao"+position);
    int positionToDelete = mAdapterNoti.getItemCount() - position - 1;
    //int posicaodb = position+1;
    Log.d("igr","positionToDelete"+positionToDelete);
    try{
        try{
            Notificacao notificacao = Notificacao.findById(Notificacao.class,positionToDelete);
            Log.d("igr",""+notificacao.getMensagem());
        }catch (Exception e){
            Log.d("igr","erro ao obter mensagem da notificao" + e);
        }
        //notificacao.delete();
        //Log.d("igr","deletou  a notificao no BD");
        //mAdapterNoti.notifyItemRemoved(position);

    }catch (Exception e){
        Log.d("igr","Erro ao deletar a notificacao no DB" + e);

    }

}

};

Answer 1

You can set the position to delete in the database this way:

int positionToDelete = adapterSize - adapterPosition;
// supondo que o índice do primeiro registro é 1, conforme documentação do Sugar.

where adapterSize is the total of Adapter (Recyclerview) and adapterPosition items is the position of the Recyclerview item that you are doing the Swipe.

If you don’t want to do any math, you can create an auxiliary method in the Adapter that returns the item id at a certain position and call this method in onSwiped() to delete the item by id.