为什么我的listview出现这种情况我看到说是因为加载速度慢的原因但是一直解决不了谁能帮忙解决一下，代码：

public View getView(int position, View convertView, ViewGroup parent) {

if(urls.contains(position)) {

convertView= images.get(position).get();

}else {

ContentHolder holder= null;

if(convertView!= null) {

holder= (ContentHolder) convertView.getTag();

}else {

convertView= inflater.inflate(R.layout.item, parent, false);

holder= new ContentHolder();

holder.icon= (ImageView) convertView.findViewById(R.id.thumbnail);

holder.name= (TextView) convertView.findViewById(R.id.item_name);

holder.size= (TextView) convertView.findViewById(R.id.item_size);

convertView.setTag(holder);

}

setContent(convertView, position, holder);

}

this.notifyDataSetChanged();

return convertView;

}