Loading RecyclerView와 SwipeRefreshLayout의 결합

RecyclerViewAdapter_post.java

public class RecyclerViewAdapter_post extends RecyclerView.Adapter<RecyclerViewAdapter_post.ItemViewHolder> {
    private Activity activity;
    private RecyclerView recyclerView;
    private PostScrollToPositionListener postScrollToPositionListener; //to notify item change, so parent should know
    private SwipeRefreshLayout refreshLayout;

    /**
     * Constructor For PostActivity
     */
    public RecyclerViewAdapter_post(final Activity activity, FragmentManager fragmentManager, RecyclerView recyclerView, SwipeRefreshLayout refreshLayout) {
        whatIsTarget = HOME;
        this.activity = activity;
        this.fragmentManager = fragmentManager;
        this.recyclerView = recyclerView;   this.refreshLayout = refreshLayout;
        postList.clear();
        currentUid = FirebaseAuth.getInstance().getCurrentUser().getUid();

        //현재 유저의 이름과 프로필 사진을 가져오는 쿼리
        firestore.collection("users").document(currentUid).get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
            @Override
            public void onSuccess(DocumentSnapshot documentSnapshot) {
                UserData userData = documentSnapshot.toObject(UserData.class);
                try {
                    currentUserName = userData.getUserName();
                    currentUserProfile=userData.getProfile();
                }catch (NullPointerException e){e.printStackTrace();}
            }
        });

        collectionReference.orderBy("timestamp", Query.Direction.DESCENDING).limit(3).get().addOnCompleteListener(onCompleteListener);
        recyclerView.addOnScrollListener(onScrollListener);
    }
  
      RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
        }

        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);
            if (!recyclerView.canScrollVertically(1) && dy > 0) {
                if (whatIsTarget == TIMELINE)
                    collectionReference.whereEqualTo("uid", uid)
                            .whereLessThan("timestamp", oldestTimeStamp)
                            .orderBy("timestamp", Query.Direction.DESCENDING)
                            .limit(3).get().addOnCompleteListener(onCompleteListener);
                else if (whatIsTarget == HOME)
                    collectionReference.whereLessThan("timestamp", oldestTimeStamp)
                            .orderBy("timestamp", Query.Direction.DESCENDING)
                            .limit(3).get().addOnCompleteListener(onCompleteListener);
            }
        }
    };

    public void swipeUpdate(final int whatIsTarget, SwipeRefreshLayout refreshLayout){
        postList.clear();
        uidList.clear();
        if(whatIsTarget==HOME)
            collectionReference.orderBy("timestamp", Query.Direction.DESCENDING).limit(3).get().addOnCompleteListener(onCompleteListener);
        else
            collectionReference.whereEqualTo("uid", uid).
                    whereGreaterThanOrEqualTo("timestamp", oldestTimeStamp).orderBy("timestamp", Query.Direction.DESCENDING).
                    get().addOnCompleteListener(onCompleteListener);
    }

    public void setPostScrollToPositionListener(PostScrollToPositionListener listener) {
        this.postScrollToPositionListener = listener;
    }

    //Firebase Firestore의 데이터를 불러오는 
    OnCompleteListener<QuerySnapshot> onCompleteListener = new OnCompleteListener<QuerySnapshot>() {
        @Override
        public void onComplete(@NonNull Task<QuerySnapshot> task) {
            if(task.isSuccessful()){
                progress.progressON(activity);
                for(QueryDocumentSnapshot item : task.getResult()) {
                    UserPost post = item.toObject(UserPost.class);
                    postList.add(post);
                    uidList.add(item.getId());
                }
                notifyDataSetChanged();
                progress.progressOFF();
                counter=post_number = postList.size();
                postCounter += postList.size();
                if (postList.size() > 0)
                    oldestTimeStamp = postList.get(postList.size() - 1).getTimestamp();
                if (isFirst == FIRST) {
                    int position = 0;
                    for (UserPost post : postList) {
                        if (post.getTimestamp().equals(selected_item_timestamp))
                            break;
                        position++;
                    }
                    postScrollToPositionListener.onSuccessListener(position);
                    isFirst = 2;
                }
                refreshLayout.setRefreshing(false);
            }
        }

    };

    @NonNull
    @Override
    public ItemViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {...}

    @Override
    public long getItemId(int position) {...}

    @Override
    public void onBindViewHolder(@NonNull final ItemViewHolder holder, final int position) {...}


    @Override
    public int getItemCount() {...}


    private void favoriteEvent(final int position, final ImageView favoriteImageView, final TextView favoriteCountTextView) {...}

    private void favoriteAlarm(String destinationUid, Long timestamp) {...}


    public class ItemViewHolder extends RecyclerView.ViewHolder {
        ...

        public ItemViewHolder(View itemView) {
            super(itemView);
            ...
        }
        public void changeFavorite(final String text, final boolean favoriteOn){...}
        View.OnClickListener onClickListener = new View.OnClickListener() {...};
    }

    private RequestListener<Drawable> requestListener = new RequestListener<Drawable>() {...};
}

SwipeRefreshLoadRecyclerView.java

public class HomeFragment extends BaseFragment {
    private static final int HOME = 0;
    private SwipeRefreshLayout refreshLayout;
    private RecyclerView recyclerView;
    private RecyclerViewAdapter_post adapter;

    ...
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = LayoutInflater.from(getActivity()).inflate(R.layout.fragment_post, container, false);
        // Inflate the layout for this fragment
        init(view);
        return view;
    }
    public void init(View view){
        refreshLayout = view.findViewById(R.id.home_fragment_layout);
        recyclerView = view.findViewById(R.id.post_recyclerView);
        adapter = new RecyclerViewAdapter_post(getActivity(),getActivity().getSupportFragmentManager(),recyclerView,refreshLayout);
        adapter.setHasStableIds(true);
        RecyclerView.ItemAnimator animator = recyclerView.getItemAnimator();
        if (animator instanceof SimpleItemAnimator) {
            ((SimpleItemAnimator) animator).setSupportsChangeAnimations(false);
        }
        adapter.setPostScrollToPositionListener(new PostScrollToPositionListener() {
            @Override
            public void onSuccessListener(final int position) {
            }
        });
        refreshLayout.setOnRefreshListener(refreshListener);
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    }
    SwipeRefreshLayout.OnRefreshListener refreshListener = new SwipeRefreshLayout.OnRefreshListener() {
        @Override
        public void onRefresh() {
            adapter.swipeUpdate(0,refreshLayout);
        }
    };
}