Helper listener class to implement pagination

EndlessRecyclerOnScrollListener.java

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

/**
 * @author gdelgado
 * @see <a href="https://gist.github.com/GuilhE/cb2284d65d9ac9f1fd07bd5723b55924">EndlessRecyclerOnScrollListener</a>
 */
@SuppressWarnings({"unused", "WeakerAccess"})
public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {

    private LinearLayoutManager layoutManager;

    public EndlessRecyclerOnScrollListener(LinearLayoutManager layoutManager) {
        this.layoutManager = layoutManager;
    }

    @Override
    public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);

        int firstVisibleItemIndex = layoutManager.findFirstVisibleItemPosition();
        int visibleItemCount = layoutManager.getChildCount();
        int totalItemCount = layoutManager.getItemCount();
        int delta = layoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL ? dx : dy;
        boolean startToEnd = !layoutManager.getReverseLayout();

        if ((startToEnd ? delta > 0 : delta < 0) && (firstVisibleItemIndex + visibleItemCount >= totalItemCount)) {
            onLoadMore(layoutManager.findLastVisibleItemPosition());
        }
    }

    public abstract void onLoadMore(int lastVisibleIndex);
}

Just create a new instance of this listener and add it to your RecyclerView:

recyclerView.addOnScrollListener(new EndlessRecyclerOnScrollListener((LinearLayoutManager) recyclerView.getLayoutManager()) {
        @Override
         public void onLoadMore(int lastVisibleIndex) {
                  //load logic
         }
});

Works with both:
Orientations: LinearLayoutManager.VERTICAL, LinearLayoutManager.HORIZONTAL
Directions: reverseLayout = false (start to end), reverseLayout = true (end to start)