ViewHolder优化

public View getView(int position, View convertView, ViewGroup parent) {        ViewHolder viewHolder=null;        if (convertView == null) {            viewHolder = new ViewHolder();            convertView = View.inflate(context, R.layout.items, null);            convertView.setTag(viewHolder);            viewHolder.image = (ImageView) convertView.findViewById(R.id.image);            viewHolder.text = (TextView) convertView.findViewById(R.id.text);        } else {            viewHolder = (ViewHolder) convertView.getTag();        }        viewHolder.text.setText(fromJson.result.list.get(position).title);        String url = fromJson.result.list.get(position).firstImg;        if (TextUtils.isEmpty(url)) {            viewHolder.image.setImageResource(R.drawable.ic_launcher);        } else {            //url = Images.imageThumbUrls[position];            BitmapUtils bitmapUtils = new BitmapUtils(context);            bitmapUtils.display(viewHolder.image, url);        }        return convertView;    }    class ViewHolder {        ImageView image;        TextView text;    }