ViewHolder模式超简洁写法

2016-07-05  本文已影响113人  六指禅

先声明,从国外网站上看的,不是自己原创的,但确实很喜欢这个简洁的设计。
ViewHolder这么写(只提供一个静态方法,其实可以加一个私有构造函数防止外部实例化),代码很简单,看过就明白了

public class ViewHolder {
// I added a generic return type to reduce the casting noise in client code
@SuppressWarnings("unchecked")
public static <T extends View> T get(View view, int id) {
SparseArray<View> viewHolder = (SparseArray<View>) view.getTag();
if (viewHolder == null) {
viewHolder = new SparseArray<View>();
view.setTag(viewHolder);
}
View childView = viewHolder.get(id);
if (childView == null) {
childView = view.findViewById(id);
viewHolder.put(id, childView);
}
return (T) childView;
}
}
在getView里这样

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

if (convertView == null) {  
    convertView = LayoutInflater.from(context)  
      .inflate(R.layout.banana_phone, parent, false);  
}  

ImageView bananaView = ViewHolder.get(convertView, R.id.banana);  
TextView phoneView = ViewHolder.get(convertView, R.id.phone);  

BananaPhone bananaPhone = getItem(position);  
phoneView.setText(bananaPhone.getPhone());  
bananaView.setImageResource(bananaPhone.getBanana());  

return convertView;  

}

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