LoadMoreAdapter.java

/**
 * @Author McGalanes
 * @Email [email protected]
 */

public class LoadMoreAdapter extends RecyclerView.Adapter {
    private final int VIEW_ITEM = 1;
    private final int VIEW_PROG = 0;

    private List<City> mCityList;

    // The minimum amount of items to have below your current scroll position
    // before mLoading more.
    private int mVisibleThreshold = 5;
    private int mLastVisibleItem, mTotalItemCount;
    private boolean mLoading;
    private OnLoadMoreListener mOnLoadMoreListener;


    public LoadMoreAdapter(List<City> students, RecyclerView recyclerView) {
        mCityList = students;

        if (recyclerView.getLayoutManager() instanceof LinearLayoutManager) {

            final LinearLayoutManager linearLayoutManager = (LinearLayoutManager) recyclerView
                    .getLayoutManager();


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

                            mTotalItemCount = linearLayoutManager.getItemCount();
                            mLastVisibleItem = linearLayoutManager
                                    .findLastVisibleItemPosition();
                            if (!mLoading
                                    && mTotalItemCount <= (mLastVisibleItem + mVisibleThreshold)) {
                                // End has been reached
                                // Do something
                                if (mOnLoadMoreListener != null) {
                                    mOnLoadMoreListener.onLoadMore();
                                }
                                mLoading = true;
                            }
                        }
                    });
        }
    }

    @Override
    public int getItemViewType(int position) {
        return mCityList.get(position) != null ? VIEW_ITEM : VIEW_PROG;
    }

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,
                                                      int viewType) {
        RecyclerView.ViewHolder vh;
        if (viewType == VIEW_ITEM) {
            View v = LayoutInflater.from(parent.getContext()).inflate(
                    R.layout.cell_item, parent, false);

            vh = new CityViewHolder(v);
        } else {
            View v = LayoutInflater.from(parent.getContext()).inflate(
                    R.layout.cell_loader, parent, false);

            vh = new ProgressViewHolder(v);
        }
        return vh;
    }


    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
        if (holder instanceof CityViewHolder) {

            City singleCity = mCityList.get(position);
            CityViewHolder.bind(singleCity);

        } else {
            ((ProgressViewHolder) holder).mProgressBar.setIndeterminate(true);
        }
    }


    public void setLoaded() {
        mLoading = false;
    }

    @Override
    public int getItemCount() {
        return mCityList.size();
    }

    public void setOnLoadMoreListener(OnLoadMoreListener onLoadMoreListener) {
        this.mOnLoadMoreListener = onLoadMoreListener;
    }

    public static class CityViewHolder extends RecyclerView.ViewHolder {

        public CityViewHolder(View itemView) {
            super(itemView);
            //inject views here
        }

        public static void bind(City singleCity) {
            //update views here
        }

    }

    public static class ProgressViewHolder extends RecyclerView.ViewHolder {
        public ProgressBar mProgressBar;

        public ProgressViewHolder(View v) {
            super(v);
            mProgressBar = (ProgressBar) v.findViewById(R.id.progressbar_id);
        }
    }

    public interface OnLoadMoreListener {
        void onLoadMore();
    }
}