ListView 的优化

//减少对象的创建
if (convertView == null) {
//实例化一个布局文件
convertView = LayoutInflater.from(context).inflate(R.layout.my_simple_adapter, null);
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
//减少对象的创建
if (convertView == null) {
//实例化一个布局文件
convertView = LayoutInflater.from(context).inflate(R.layout.my_simple_adapter, null);
viewHolder = new ViewHolder();
viewHolder.img = (ImageView) convertView.findViewById(R.id.img);
viewHolder.title = (TextView) convertView.findViewById(R.id.text);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
System.out.println(convertView);
viewHolder.title.setText(titles[position]);
viewHolder.img.setImageResource(icons[position]);
return convertView;
}
//用于保存第一次查找的组件, 避免下次重复查找
static class ViewHolder {
//不封装  效率更高
ImageView img;
TextView title;
}
}