nesquena/EndlessRecyclerViewScrollListener.java Secret

## EndlessRecyclerViewScrollListener.java
public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
    // The minimum amount of items to have below your current scroll position
    // before loading more.
    private int visibleThreshold = 5;
    // The current offset index of data you have loaded
    private int currentPage = 0;
    // The total number of items in the dataset after the last load
    private int previousTotalItemCount = 0;
    // True if we are still waiting for the last set of data to load.
    private boolean loading = true;
    // Sets the starting page index
    private int startingPageIndex = 0;

    RecyclerView.LayoutManager mLayoutManager;

    public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
    }

    public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) {
        this.mLayoutManager = layoutManager;
        visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
    }

    public int getLastVisibleItem(int[] lastVisibleItemPositions) {
        int maxSize = 0;
        for (int i = 0; i < lastVisibleItemPositions.length; i++) {
            if (i == 0) {
                maxSize = lastVisibleItemPositions[i];
            }
            else if (lastVisibleItemPositions[i] > maxSize) {
                maxSize = lastVisibleItemPositions[i];
            }
        }
        return maxSize;
    }

    // This happens many times a second during a scroll, so be wary of the code you place here.
    // We are given a few useful parameters to help us work out if we need to load some more data,
    // but first we check if we are waiting for the previous load to finish.
    @Override
    public void onScrolled(RecyclerView view, int dx, int dy) {
        int lastVisibleItemPosition = 0;
        int totalItemCount = mLayoutManager.getItemCount();

        if (mLayoutManager instanceof StaggeredGridLayoutManager) {
            int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
            // get maximum element within the list
            lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
        } else if (mLayoutManager instanceof GridLayoutManager) {
            lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        } else if (mLayoutManager instanceof LinearLayoutManager) {
            lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
        }

        // If the total item count is zero and the previous isn't, assume the
        // list is invalidated and should be reset back to initial state
        if (totalItemCount < previousTotalItemCount) {
            this.currentPage = this.startingPageIndex;
            this.previousTotalItemCount = totalItemCount;
            if (totalItemCount == 0) {
                this.loading = true;
            }
        }
        // If it’s still loading, we check to see if the dataset count has
        // changed, if so we conclude it has finished loading and update the current page
        // number and total item count.
        if (loading && (totalItemCount > previousTotalItemCount)) {
            loading = false;
            previousTotalItemCount = totalItemCount;
        }

        // If it isn’t currently loading, we check to see if we have breached
        // the visibleThreshold and need to reload more data.
        // If we do need to reload some more data, we execute onLoadMore to fetch the data.
        // threshold should reflect how many total columns there are too
        if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
            currentPage++;
            onLoadMore(currentPage, totalItemCount, view);
            loading = true;
        }
    }

    // Call this method whenever performing new searches
    public void resetState() {
        this.currentPage = this.startingPageIndex;
        this.previousTotalItemCount = 0;
        this.loading = true;
    }

    // Defines the process for actually loading more data based on page
    public abstract void onLoadMore(int page, int totalItemsCount, RecyclerView view);

}
	public abstract class EndlessRecyclerViewScrollListener extends RecyclerView.OnScrollListener {
	// The minimum amount of items to have below your current scroll position
	// before loading more.
	private int visibleThreshold = 5;
	// The current offset index of data you have loaded
	private int currentPage = 0;
	// The total number of items in the dataset after the last load
	private int previousTotalItemCount = 0;
	// True if we are still waiting for the last set of data to load.
	private boolean loading = true;
	// Sets the starting page index
	private int startingPageIndex = 0;

	RecyclerView.LayoutManager mLayoutManager;

	public EndlessRecyclerViewScrollListener(LinearLayoutManager layoutManager) {
	this.mLayoutManager = layoutManager;
	}

	public EndlessRecyclerViewScrollListener(GridLayoutManager layoutManager) {
	this.mLayoutManager = layoutManager;
	visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
	}

	public EndlessRecyclerViewScrollListener(StaggeredGridLayoutManager layoutManager) {
	this.mLayoutManager = layoutManager;
	visibleThreshold = visibleThreshold * layoutManager.getSpanCount();
	}

	public int getLastVisibleItem(int[] lastVisibleItemPositions) {
	int maxSize = 0;
	for (int i = 0; i < lastVisibleItemPositions.length; i++) {
	if (i == 0) {
	maxSize = lastVisibleItemPositions[i];
	}
	else if (lastVisibleItemPositions[i] > maxSize) {
	maxSize = lastVisibleItemPositions[i];
	}
	}
	return maxSize;
	}

	// This happens many times a second during a scroll, so be wary of the code you place here.
	// We are given a few useful parameters to help us work out if we need to load some more data,
	// but first we check if we are waiting for the previous load to finish.
	@Override
	public void onScrolled(RecyclerView view, int dx, int dy) {
	int lastVisibleItemPosition = 0;
	int totalItemCount = mLayoutManager.getItemCount();

	if (mLayoutManager instanceof StaggeredGridLayoutManager) {
	int[] lastVisibleItemPositions = ((StaggeredGridLayoutManager) mLayoutManager).findLastVisibleItemPositions(null);
	// get maximum element within the list
	lastVisibleItemPosition = getLastVisibleItem(lastVisibleItemPositions);
	} else if (mLayoutManager instanceof GridLayoutManager) {
	lastVisibleItemPosition = ((GridLayoutManager) mLayoutManager).findLastVisibleItemPosition();
	} else if (mLayoutManager instanceof LinearLayoutManager) {
	lastVisibleItemPosition = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition();
	}

	// If the total item count is zero and the previous isn't, assume the
	// list is invalidated and should be reset back to initial state
	if (totalItemCount < previousTotalItemCount) {
	this.currentPage = this.startingPageIndex;
	this.previousTotalItemCount = totalItemCount;
	if (totalItemCount == 0) {
	this.loading = true;
	}
	}
	// If it’s still loading, we check to see if the dataset count has
	// changed, if so we conclude it has finished loading and update the current page
	// number and total item count.
	if (loading && (totalItemCount > previousTotalItemCount)) {
	loading = false;
	previousTotalItemCount = totalItemCount;
	}

	// If it isn’t currently loading, we check to see if we have breached
	// the visibleThreshold and need to reload more data.
	// If we do need to reload some more data, we execute onLoadMore to fetch the data.
	// threshold should reflect how many total columns there are too
	if (!loading && (lastVisibleItemPosition + visibleThreshold) > totalItemCount) {
	currentPage++;
	onLoadMore(currentPage, totalItemCount, view);
	loading = true;
	}
	}

	// Call this method whenever performing new searches
	public void resetState() {
	this.currentPage = this.startingPageIndex;
	this.previousTotalItemCount = 0;
	this.loading = true;
	}

	// Defines the process for actually loading more data based on page
	public abstract void onLoadMore(int page, int totalItemsCount, RecyclerView view);

	}