RxJava Android and Infinite Scrolling

RxEndlessScroller.java

public class RxEndlessScroller {
    interface OnLoadMoreListener {
        void loadMore();
    }

    private static class EndlessScrollListener extends RecyclerView.OnScrollListener {
        private final int visibleItemCountThreshold;

        @Nullable private OnLoadMoreListener loadMoreListener;

        private int lastItemCount;
        private int currentItemCount;

        private int firstVisibleItemPosition;
        private int visibleItemCount;

        private boolean loading;

        public EndlessScrollListener(int visibleItemCountThreshold) {
            this.visibleItemCountThreshold = visibleItemCountThreshold;
            reset();
        }

        public void setLoadMoreListener(@Nullable OnLoadMoreListener loadMoreListener) {
            this.loadMoreListener = loadMoreListener;
        }

        public void reset() {
            lastItemCount = 0;
            currentItemCount = 0;
            firstVisibleItemPosition = 0;
            visibleItemCount = 0;
            loading = true;
        }

        @Override
        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
            if (dy > 0) {
                final RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
                visibleItemCount = recyclerView.getChildCount();
                currentItemCount = layoutManager.getItemCount();
                firstVisibleItemPosition = getFirstVisibleItemPosition(layoutManager);

                if (loading && currentItemCount > lastItemCount) {
                    loading = false;
                    lastItemCount = currentItemCount;
                }

                final int triggerPosition = firstVisibleItemPosition + visibleItemCountThreshold;
                final boolean loadMore = triggerPosition >= (currentItemCount - visibleItemCount);
                if (!loading && loadMore) {
                    Timber.d("End reached. Load more");
                    if (loadMoreListener != null) {
                        loadMoreListener.loadMore();
                    }
                    loading = true;
                }
            }
        }
        
        private int getFirstVisibleItemPosition(@NonNull RecyclerView.LayoutManager layoutManager) {
            if (layoutManager instanceof LinearLayoutManager) {
                return ((LinearLayoutManager) layoutManager).findFirstVisibleItemPosition();
            }
            return 0;
        }
    }
    
    @NonNull private final EndlessScrollListener endlessScrollListener;
    public RxEndlessScroller(int visibleItemThreshold) {
        endlessScrollListener = new EndlessScrollListener(visibleItemThreshold);
    }
    
    public Observable<Event> loadMore() {
        return Observable.create(emitter -> {
            final OnLoadMoreListener loadMoreListener = () -> emitter.onNext(Event.loadMore());
            endlessScrollListener.setLoadMoreListener(loadMoreListener);

            emitter.setCancellation(() -> endlessScrollListener.setLoadMoreListener(null));
        }, Emitter.BackpressureMode.LATEST);
    }
}