无法显示来自XML Feed的图像-holder.imageView.setImageURI（cmd.getImageUrl（））; 返回null

Question

I'm attempting to create a thumbnail from a URL obtained from an XML feed. My problem is when I reach the line:

public  Uri getImageUrl() {
    return imageurl;
}

public void setImageUrl(Uri imageurl) {
    this.imageurl = imageurl;
}

it is returning null. I'm not sure exactly why but ever since I implemented the call to pull the thumbnail - I have not been able to display them - although I do not have any nullpointer exceptions and the code seems to execute without error.

   public class CustomListViewAdapter extends ArrayAdapter<Cmd> {
        Activity context;
        List<Cmd> videos;

        public CustomListViewAdapter(Activity context, List<Cmd> videos) {
            super(context, R.layout.list_item2, videos);

            this.context = context;
            this.videos = videos;
        }

        /* private view holder class */
        private class ViewHolder {
            ImageView imageView;
            TextView txtSuccess;
            TextView txtCmd;
            TextView txtPrice;
        }

        public void run(Cmd cmd) {
            Intent intent = new Intent(context, ViewVideo.class);
            String txt=cmd.getVideoURL(); 
            intent.putExtra("videofilename", txt);
            context.startActivity(intent);
        }



        public Cmd getItem(int position) {
            return videos.get(position);
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder;
            LayoutInflater inflater = context.getLayoutInflater();
            if (convertView == null) {

                convertView = inflater.inflate(R.layout.list_item2, null);
                holder = new ViewHolder();
                holder.txtSuccess = (TextView) convertView
                        .findViewById(R.id.success);
                holder.txtCmd = (TextView) convertView.findViewById(R.id.cmd);
                holder.txtPrice = (TextView) convertView.findViewById(R.id.price);
                holder.imageView = (ImageView) convertView
                        .findViewById(R.id.thumbnail);
                convertView.setTag(holder);

            } else {
                holder = (ViewHolder) convertView.getTag();
            }

            final Cmd cmd = (Cmd) getItem(position);

            holder.txtSuccess.setText(cmd.getVideoName());
            holder.txtSuccess.setOnClickListener(new View.OnClickListener() {

                public void onClick(View v) {
                    run(cmd);
                }
            });
            holder.txtCmd.setText(cmd.getCmd());
            holder.txtCmd.setOnClickListener(new View.OnClickListener() {

                public void onClick(View v) {
                    run(cmd);
                }
            });

        //  holder.txtPrice.setText(cmd.getVideoURL());
    //      holder.txtPrice.setOnClickListener(new View.OnClickListener() {
    //
    //          public void onClick(View v) {
    //              run(cmd);
    //          }
    //      });
            holder.imageView.setImageURI(cmd.getImageUrl());
            holder.imageView.setOnClickListener(new View.OnClickListener() {

                public void onClick(View v) {
                    run(cmd);
                }
            });
            return convertView;

        }

    }

Answer 1

You could save yourself a lot of headache and gain benefits like caching and using a placeholder image by using the Picasso library. In a single line ( Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView); ) you can tell a URL to load into an ImageView when it has downloaded, have that image cached and, with one more method call, you can set a placeholder drawable. And you can lose a whole tonne of boilerplate code.