Pagination

PaginatiomCallback

public interface PaginationCallback {

    boolean isRefreshing();

    void setRefreshing(boolean refreshing);

    void getPage(int page);

    UltimateAdapter getAdapter();

}

PaginationScrollListener

public class PaginationScrollListener extends RecyclerView.OnScrollListener {

    private static final String TAG = "PaginationScrollListener";
    private static final int ITEMS_OFFSET_TO_LOAD_DEFAULT = 3;

    private final OnRecyclerViewScrolledToPageListener mCallback;
    private final int mOffset;
    private LinearLayoutManager mLayoutManager;
    private boolean loading;
    private int previousTotal;
    public interface OnRecyclerViewScrolledToPageListener {

        void onRecyclerViewScrolledToEnd();
    }

    public PaginationScrollListener(OnRecyclerViewScrolledToPageListener callback) {
        this.mCallback = callback;
        this.mOffset = ITEMS_OFFSET_TO_LOAD_DEFAULT;
        if (mCallback == null) {
            throw new IllegalStateException("OnRecyclerViewScrolledToPageListener is NULL");
        }
    }

    @Override
    public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
        super.onScrollStateChanged(recyclerView, newState);
    }

    @Override
    public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        super.onScrolled(recyclerView, dx, dy);
        if (mLayoutManager == null) {
            mLayoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
        }

        final int visibleItemCount = recyclerView.getChildCount();
        final int totalItemCount = mLayoutManager.getItemCount();
        final int firstVisibleItem = mLayoutManager.findFirstCompletelyVisibleItemPosition();
        final int lastVisibleItem = firstVisibleItem + visibleItemCount;
        if (loading) {
            if (totalItemCount != previousTotal) {
                loading = false;
                previousTotal = totalItemCount;
            }
        }

        if (!loading && (lastVisibleItem + mOffset) > totalItemCount) {
            // End has been reached

            mCallback.onRecyclerViewScrolledToEnd();

            // Do something

            loading = true;
        }

    }

    public void reset() {
        loading = false;
        previousTotal = -1;
    }
}

PaginationSupport

public class PaginationSupport implements PaginationScrollListener.OnRecyclerViewScrolledToPageListener, PullRefreshLayout.OnPullRefreshListener {

    private static final String TAG = "PaginationSupport";
    private final int mFirstPageNumber;
    private final PaginationScrollListener mPaginationScrollListener;
    private final PaginationCallback mPaginationCallback;
    private int mPage;
    private boolean mIsLoading = false;

    public PaginationSupport(PaginationCallback paginationCallback, RecyclerView recycler, int firstPageNumber) {
        mPaginationCallback = paginationCallback;
        mFirstPageNumber = firstPageNumber;
        mPage = firstPageNumber;
        mPaginationScrollListener = new PaginationScrollListener(this);
        recycler.addOnScrollListener(mPaginationScrollListener);
    }

    @Override
    public void onRecyclerViewScrolledToEnd() {
        if (getAdapter() != null && getAdapter().getDataSize() > 0) {
            getAdapter().setFooterVisibility(true);
            loadPage();
        }
    }

    @Override
    public void onRefresh() {
        reset();
    }

    public void onLoadComplete(boolean loaded) {
        mIsLoading = false;
        if (isRefreshing()) {
            setRefreshing(false);
        }
        getAdapter().setFooterVisibility(false);
        if (loaded) {
            mPage++;
        }
    }

    public void loadPage() {
        if (mIsLoading) {
            return;
        }
        mIsLoading = true;
        if (mPage == mFirstPageNumber) {
            setRefreshing(true);
        }
        getPage(mPage);
    }

    public void reset() {
        mPaginationScrollListener.reset();
        mPage = mFirstPageNumber;
        getAdapter().clear();
        getAdapter().notifyDataSetChanged();
        loadPage();
    }

    private boolean isRefreshing() {
        return mPaginationCallback.isRefreshing();
    }

    private void setRefreshing(boolean refreshing) {
        mPaginationCallback.setRefreshing(refreshing);
    }

    private void getPage(int page) {
        mPaginationCallback.getPage(page);
    }

    private UltimateAdapter getAdapter() {
        return mPaginationCallback.getAdapter();
    }
}