new SimpleRvAdapter<Repo>(items, R.layout.item_repo) {
  @Override
  public void bindView(@NonNull RvHolder holder, @NonNull Repo data) {
    holder.getHelper()
      .setText(R.id.tv_name, data.getName())
      .setText(R.id.tv_description, data.getDescription())
      .setText(R.id.tv_license, data.getLicense().getName())
      .setText(R.id.tv_html_link, Html.fromHtml(data.getHtmlUrl()));
  }
};

AdapterHelper.newSimpleRvAdapter(
  items, 
  new CourseViewBinder()
);


public class CourseViewBinder implements ViewBinder2<Course> {
  @Override
  public int itemLayout() {
    return R.layout.item_course;
  }

  @Override
  public void bindView(@NonNull AdapterViewHolder holder, Course data) {
    holder.setText(R.id.tv_serial_number, Integer.toString(holder.getPosition()))
      .setText(R.id.tv_name, data.getName())
      .setText(R.id.tv_description, data.getDescription());
  }
}

public class GroupChoiceDemoRvAdapter extends GroupChoiceRvAdapter {
    public static final int TYPE_GROUP = 1;
    public static final int TYPE_GROUP_ITEM = 2;

    private final ArrayMap<Integer, List<Integer>> mData;
    private final ArrayMap<String, Boolean> mSelectedStatus = new ArrayMap<>();

    public GroupChoiceDemoRvAdapter(@NonNull ArrayMap<Integer, List<Integer>> data) {
        mData = data;
    }

    @Override
    public int getGroupViewType(int groupPosition) {
        return TYPE_GROUP;
    }

    @Override
    public int getGroupItemViewType(int groupPosition, int groupItemPosition) {
        return TYPE_GROUP_ITEM;
    }

    @Override
    public int getGroupCount() {
        return mData.size();
    }

    @Override
    public int getGroupItemCount(int groupPosition) {
        return mData.valueAt(groupPosition).size();
    }

    @Override
    public void bindGroupView(@NonNull RvHolder holder, int groupPosition) {
        holder.getHelper().setText(R.id.tv_title, "group(" + groupPosition + "): " + mData.keyAt(groupPosition));
    }

    @Override
    public void bindGroupItemView(@NonNull RvHolder holder, int groupPosition, int groupItemPosition) {
        holder.getHelper().setText(R.id.tv_content, "(" + groupPosition + ", " + groupItemPosition + "): " + mData.valueAt(groupPosition).get(groupItemPosition));
    }

    @Override
    protected int getLayoutResId(int viewType) {
        switch (viewType) {
            case TYPE_GROUP:
                return R.layout.item_title;
            case TYPE_GROUP_ITEM:
                return R.layout.item_content;
            default:
                throw new IllegalArgumentException("illegal viewType: " + viewType);
        }
    }

    @Override
    public void updateGroup(int groupPosition, boolean selected) {
        String key = groupPosition + "_NO";
        mSelectedStatus.put(key, selected);
    }

    @Override
    public void updateGroupItem(int groupPosition, int groupItemPosition, boolean selected) {
        String key = groupPosition + "_" + groupItemPosition;
        mSelectedStatus.put(key, selected);
    }


    @Override
    public boolean isGroupSelected(int groupPosition) {
        Boolean selected = mSelectedStatus.get(groupPosition + "_NO");
        return selected != null ? selected : false;
    }

    @Override
    public boolean isGroupItemSelected(int groupPosition, int groupItemPosition) {
        Boolean selected = mSelectedStatus.get(groupPosition + "_" + groupItemPosition);
        return selected != null ? selected : false;
    }

    @Override
    public boolean isGroupSelectable(int groupPosition) {
        return false;
    }
}