ViewHolder简单写法

最新推荐文章于 2025-05-17 11:57:58 发布

转载最新推荐文章于 2025-05-17 11:57:58 发布 · 674 阅读

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本文介绍了一种优化ViewHolder模式的方法，通过泛型返回类型减少客户端代码的强制类型转换噪音，并展示了如何在ListView适配器中实现该模式，提高视图组件的复用效率。

public 
class ViewHolder { 
    // I added a generic return type to reduce the casting noise in client code
    @SuppressWarnings("unchecked")
    publicstatic
<T extendsView> T get(View view,
intid) { 
        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;
    }
}

@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());
  
    returnconvertView;
}