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每次学习了ListView后，时间一长，又忘记了。

如何使用

简单的文字

对应xml文件

对应的java代码

public class SimpleActivity extends AppCompatActivity {    private String[] data = {"apple","Banana","Orange","Watermelon","pear","Grape","Pineapple",            "apple","Banana","Orange","Watermelon","pear","Grape","Pineapple"};    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_simple);        ArrayAdapter
   
     adapter = new ArrayAdapter
    
     (SimpleActivity.this, android.R.layout.simple_list_item_1,data);        ListView listView = (ListView) findViewById(R.id.list_view);        listView.setAdapter(adapter);    }}
    
   

结果如下：

复杂的图片加文字

对应的xml代码：

//文件 activity_complex.xml
   
       
        
    
   //文件：fruit_item.xml
   
       
        
    
   

对应的java代码：

// 文件：ComplexActivity.javapublic class ComplexActivity extends AppCompatActivity {    private List
   
     fruitList = new ArrayList
    
     ();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_complex);        initFruits(); // 初始化水果数据        FruitAdapter adapter = new FruitAdapter(ComplexActivity.this, R.layout.fruit_item, fruitList);        ListView listView = (ListView) findViewById(R.id.list_view);        listView.setAdapter(adapter);        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView
      parent, View view,                                    int position, long id) {                Fruit fruit = fruitList.get(position);                Toast.makeText(ComplexActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();            }        });    }    private void initFruits() {        for (int i = 0; i < 2; i++) {            Fruit apple = new Fruit("Apple", R.drawable.apple_pic);            fruitList.add(apple);            Fruit banana = new Fruit("Banana", R.drawable.banana_pic);            fruitList.add(banana);            Fruit orange = new Fruit("Orange", R.drawable.orange_pic);            fruitList.add(orange);            Fruit watermelon = new Fruit("Watermelon", R.drawable.watermelon_pic);            fruitList.add(watermelon);            Fruit pear = new Fruit("Pear", R.drawable.pear_pic);            fruitList.add(pear);            Fruit grape = new Fruit("Grape", R.drawable.grape_pic);            fruitList.add(grape);            Fruit pineapple = new Fruit("Pineapple", R.drawable.pineapple_pic);            fruitList.add(pineapple);            Fruit strawberry = new Fruit("Strawberry", R.drawable.strawberry_pic);            fruitList.add(strawberry);            Fruit cherry = new Fruit("Cherry", R.drawable.cherry_pic);            fruitList.add(cherry);            Fruit mango = new Fruit("Mango", R.drawable.mango_pic);            fruitList.add(mango);        }    }}//文件：FruitAdapter.javapublic class FruitAdapter extends ArrayAdapter
     
       {    private int resourceId;    public FruitAdapter(Context context, int textViewResourceId,                        List
      
        objects) {        super(context, textViewResourceId, objects);        resourceId = textViewResourceId;    }    /**     * 获取每隔item的显示内容     * @param position     * @param convertView     * @param parent     * @return     */    @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, parent, false);            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());        return view;    }    class ViewHolder {        ImageView fruitImage;        TextView fruitName;    }}//文件： Fruit.javapublic class Fruit {    private String name;    private int imageId;    public Fruit(String name, int imageId) {        this.name = name;        this.imageId = imageId;    }    public String getName() {        return name;    }    public int getImageId() {        return imageId;    }}
      
     
    
   

实际结果如下：

优化

主要是针对 FruitAdapter 的   public View getView(int position, View convertView, ViewGroup parent)  函数优化，

（1）其中 convertView 参数的作用是，将之前加载好的布局进行缓存，以便以后可以进行重用。

（2）将 ViewHolder 存储在 View 中，这样每次在 getView 时，不会再调用 View 的 findViewById() 方法。