CardView不显示URL中的图像

Question

我创建了CardViews，它会显示作为背景输入的URL中的图像，但不知何故卡片上没有任何显示。

我实际上正在使用RecyclerView和FireBase数据库来显示卡片。

RecyclerViewAdapter

class RecyclerViewAdapter extends 
RecyclerView.Adapter<RecyclerViewAdapter.MyHoder> {
    private List<Groups> list;
    private Context context;

    public RecyclerViewAdapter(List<Groups> list, Context context) {
        this.list = list;
        this.context = context;
    }

    @Override
    public MyHoder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.recycler_view_groups,parent,false);
        MyHoder myHoder = new MyHoder(view);
        return myHoder;
    }

    @Override
    public void onBindViewHolder(MyHoder holder, int position) {
        Groups mylist = list.get(position);
        holder.name.setText(mylist.getGroupName());
        holder.banner.setImageDrawable(LoadImageFromWebOperations(mylist.getGroupBannerImage()));

        //^^Image assignment to the ImageView not working
        //mylist.getGroupBannerImage() returns the URL string of the image I want as the card's background
    }

    public static Drawable LoadImageFromWebOperations(String url) {
        try {
            InputStream is = (InputStream) new URL(url).getContent();
            Drawable d = Drawable.createFromStream(is, "src name");
            return d;
        } catch (Exception e) {
            return null;
        }
    }

    @Override
    public int getItemCount() {
        int arr = 0;
        try{
            if(list.size()==0){
                arr = 0;
            }
            else{
                arr=list.size();
            }
        }catch (Exception e){

        }
        return arr;
    }

    class MyHoder extends RecyclerView.ViewHolder{
        TextView name,address;
        ImageView banner;

        public MyHoder(View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.groupName);
            banner= (ImageView) itemView.findViewById(R.id.groupBannerImage);
            //address= (TextView) itemView.findViewById(R.id.vaddress);

        }
    }
}

我缺少什么吗？我的其他显示数据在CardView中正确显示，但只有图像没有出现。