Infinite scroll functionality for recycler views

InfiniteScrollProvider.java

import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.util.Log;

/**
 * Created by MyInnos on 28-11-2016.
 */

public class InfiniteScrollProvider {

    /**
     * {@link RecyclerView} that we want to provide infinite scrolling behavior for it
     */
    private RecyclerView recyclerView;

    /**
     * used to determine currently user is waiting for loading items or not
     */
    private boolean isLoading = false;

    /**
     * listener that trigger when user reach end of list.
     */
    private OnLoadMoreListener onLoadMoreListener;

    /**
     * {@link GridLayoutManager} that is attached to {@link #recyclerView}
     * <p/>
     * used to determine {@link #lastVisibleItem},{@link #totalItemCount},{@link #previousItemCount}
     */
    private RecyclerView.LayoutManager layoutManager;

    /**
     * position of last visible item
     */
    private int lastVisibleItem;

    /**
     * total items count of {@link #recyclerView}
     */
    private int totalItemCount;

    /**
     * total items count, relate to before last {@link #onLoadMoreListener} call.
     */
    private int previousItemCount = 0;

    /**
     * {@link #onLoadMoreListener} called when {@link #recyclerView} reach to item with position {@link #totalItemCount} - {@value THRESHOLD}
     */
    private static final int THRESHOLD = 3;

    /**
     * this function attach {@link #recyclerView} to provide infinite scroll for it
     *
     * @param recyclerView       see {@link #recyclerView} for more information
     * @param onLoadMoreListener callback for notifying when user reach list ends.
     */
    public void attach(RecyclerView recyclerView, OnLoadMoreListener onLoadMoreListener) {
        this.recyclerView = recyclerView;
        this.onLoadMoreListener = onLoadMoreListener;
        layoutManager =recyclerView.getLayoutManager();
        setInfiniteScrollGrid(layoutManager);
    }

    /**
     * this function get scrolling control of {@link #recyclerView} and whenever
     * user reached list ends, {@link #onLoadMoreListener#onLoadMoreListener} will be called
     */
    private void setInfiniteScrollGrid(final RecyclerView.LayoutManager layoutManager) {
        recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                totalItemCount = layoutManager.getItemCount();
                if (previousItemCount > totalItemCount) {
                    previousItemCount = totalItemCount - THRESHOLD;
                }
                if (layoutManager instanceof GridLayoutManager){
                    lastVisibleItem = ((GridLayoutManager)layoutManager).findLastVisibleItemPosition();
                }else if (layoutManager instanceof LinearLayoutManager){
                    lastVisibleItem = ((LinearLayoutManager)layoutManager).findLastVisibleItemPosition();
                }else if (layoutManager instanceof StaggeredGridLayoutManager){
                    StaggeredGridLayoutManager staggeredGridLayoutManager=(StaggeredGridLayoutManager) layoutManager;
                    int spanCount=staggeredGridLayoutManager.getSpanCount();
                    int[] ids=new int[spanCount];
                    staggeredGridLayoutManager.findLastVisibleItemPositions(ids);
                    int max=ids[0];
                    for (int i = 1; i < ids.length; i++) {
                        if (ids[1]>max){
                            max=ids[1];
                        }
                    }
                    lastVisibleItem=max;
                }
                if (totalItemCount > THRESHOLD) {
                    if (previousItemCount <= totalItemCount && isLoading) {
                        isLoading = false;
                        Log.i("InfiniteScroll", "Data fetched");
                    }
                    if (!isLoading && (lastVisibleItem > (totalItemCount - THRESHOLD)) && totalItemCount > previousItemCount) {
                        if (onLoadMoreListener != null) {
                            onLoadMoreListener.onLoadMore();
                        }
                        Log.i("InfiniteScroll", "End Of List");
                        isLoading = true;
                        previousItemCount = totalItemCount;
                    }
                }
                super.onScrolled(recyclerView, dx, dy);
            }
        });
    }

}

MainActivity.java

  RecyclerView recyclerView = (RecyclerView) findViewById(R.id.recyclerView);

  // you can attach your recycler view with infiniteScrollProvider like this:
  InfiniteScrollProvider infiniteScrollProvider = new InfiniteScrollProvider();
  infiniteScrollProvider.attach(recyclerView, new OnLoadMoreListener() {
    @Override
    public void onLoadMore() {
      //this method called when recycler view scrolled to the end
    }
  });

OnLoadMoreListener.java

/**
 * Created by MyInnos on 28-11-2016.
 */
public interface OnLoadMoreListener {
    void onLoadMore();
}