MainActivity.java

// Instantiate Paging Adapter
mAdapter = new FirestorePagingAdapter<Post, PostViewHolder>(options) {
    @NonNull
    @Override
    public PostViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = getLayoutInflater().inflate(R.layout.item_post, parent, false);
        return new PostViewHolder(view);
    }

    @Override
    protected void onBindViewHolder(@NonNull PostViewHolder viewHolder, int i, @NonNull Post post) {
        // Bind to ViewHolder
        viewHolder.bind(post);
    }

    @Override
    protected void onError(@NonNull Exception e) {
        super.onError(e);
        Log.e("MainActivity", e.getMessage());
    }

    @Override
    protected void onLoadingStateChanged(@NonNull LoadingState state) {
        switch (state) {
            case LOADING_INITIAL:
            case LOADING_MORE:
                mSwipeRefreshLayout.setRefreshing(true);
                break;

            case LOADED:
                mSwipeRefreshLayout.setRefreshing(false);
                break;

            case ERROR:
                Toast.makeText(
                        getApplicationContext(),
                        "Error Occurred!",
                        Toast.LENGTH_SHORT
                ).show();

                mSwipeRefreshLayout.setRefreshing(false);
                break;

            case FINISHED:
                mSwipeRefreshLayout.setRefreshing(false);
                break;
        }
    }

};