Firebase recyclerview滚动以加载更多数据

Question

我正在使用下面的代码通过firebase recyclerview检索我的数据库中的数据。我能够检索所有数据，但它们一次被检索。我希望一次检索少量数据，更多应该是当用户向上滚动时加载。我该怎么做？

databaseReference.addValueEventListener(new ValueEventListener() {

            @Override
            public void onDataChange(DataSnapshot dataSnapshot){
                if(dataSnapshot.child("Male").hasChild(user_id)){

                    query = databaseReference1.child("Female").orderByChild("halls").equalTo(halls2); 
                    query.keepSynced(true);

                }
                else{

                    query = databaseReference1.child("Male").orderByChild("halls").equalTo(halls1); 
                    query.keepSynced(true);


                }

                FirebaseRecyclerAdapter<User, tab1.UserViewholder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<User, tab1.UserViewholder>(
                        User.class, R.layout.users_row, tab1.UserViewholder.class, query) {
                    @Override
                    protected void populateViewHolder(tab1.UserViewholder viewHolder, User model, int position) {

                        final String postUser_id = getRef(position).getKey();
                        Log.v("key",postUser_id);
                        //postUserId = postkey of card
                        final String user_id = firebaseAuth.getCurrentUser().getUid();
                        //final Match match = new Match(username,  downloadUrl );


                        viewHolder.setUsername(model.getUsername());
                        viewHolder.setLevels(model.getLevels());
                        viewHolder.setDownloadUrl(getActivity().getApplicationContext(), model.getDownloadUrl());
}

                };

                users2.setAdapter(firebaseRecyclerAdapter);
            }


            @Override
            public  void onCancelled(DatabaseError databaseError){

            }
        });