Android RecycleView does not show data in list

Question

 this.books = new ArrayList<>();
            mFirebaseDatabaseReference.child(SellBooksPost).addValueEventListener(new ValueEventListener() {
                @Over         


        

Answer 1

It's hard to say if this is a problem, but I do not see a call to RecyclerView.Adapter#notifyDataSetChanged() method after updating the data. So try call

salesBookAdapter.notifyDataSetChanged()

after

books.add(new Book(
     AmessageSnapshot.child("SellBooksPostId").getValue().toString(),
     AmessageSnapshot.child("bookTitle").getValue().toString()
));