如何将新添加的数据从Firebase添加到recyclerview的顶部而不是底部？

Question

此应用使用卡片视图列表项并连接firebase实时数据库（JSON文件）
我的问题是，在新添加的数据（图像）移到列表底部之后，更新数据库。我想在顶部获取新的添加数据。如何获得

public class WallpapersAdapter extends RecyclerView.Adapter<WallpapersAdapter.WallpaperViewHolder> {
private Context mCtx;
private List<Wallpaper> wallpaperList;
public WallpapersAdapter(Context mCtx, List<Wallpaper> wallpaperList) {
    this.mCtx = mCtx;
    this.wallpaperList = wallpaperList;
}
@Override
public WallpaperViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(mCtx).inflate(R.layout.recyclerview_wallpapers, parent, false);
    return new WallpaperViewHolder(view);
}


@Override
public void onBindViewHolder( WallpaperViewHolder holder, int position) {
    if (position == getItemCount() - 1){

        Wallpaper w = wallpaperList.get(position);
        holder.textView.setText(w.title);
        Glide.with(mCtx)
                .load(w.url)
                .into(holder.imageView);
        if (w.isFavourite) {
            holder.checkBoxFav.setChecked(true);
        }

    }


}

请帮助我...