ListView的优化

package
com.example.chenac.listviewtest;

import
android.content.Context;
import
android.media.Image;
import
android.util.Log;
import
android.view.LayoutInflater;
import
android.view.View;
import
android.view.ViewGroup;
import
android.widget.ArrayAdapter;
import
android.widget.ImageView;
import
android.widget.TextView;

import
java.util.List;

/**

* Created by CHENAC on 10/8/2015.

*/
public class
FruitAdapter
extends
ArrayAdapter<Fruit> {

   
private int
resourceId;

   
public
FruitAdapter(Context context,
int
textViewResourceId, List<Fruit> objects) {

       
super(context, textViewResourceId, objects);

       
resourceId=textViewResourceId;

        Log.d(
"FruitAdapter","11111111111111"
);

    }

   
//在每个子项被滚动到屏幕内的时候会被调用

  
@Override

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

       Fruit fruit=getItem(position);//获取当前项的Fruit实例

       View view;

       ViewHolder viewHolder;

      
if
(convertView==null)
{

          view = LayoutInflater.from
(getContext()).inflate(resourceId,
null); 
//先取出一个单元行的View的布局

          
viewHolder=
new
ViewHolder();

           viewHolder.fruitImage
= (ImageView) view.findViewById

                   (R.id.fruit_image);

           viewHolder.fruitName
= (TextView) view.findViewById

                   (R.id.fruit_name);

           view.setTag(viewHolder);
// 将ViewHolder存储在View中

       }
else
{

           view=convertView;

           viewHolder = (ViewHolder) view.getTag();
// 重新获取ViewHolder

       }

       viewHolder.fruitImage.setImageResource(fruit.getImageId());

       viewHolder.fruitName.setText(fruit.getName());                                  
//设置名字

      
return 
view;

   }

   
class 
ViewHolder{

        ImageView
fruitImage;

        TextView
fruitName;

    }

}