自定义ListView步骤

1.为ListView的子项创建一个自定义布局，在Layout目录下新建一个xxx_item.xml文件；
2.创建一个实体类，作为ListView适配器的适配类型。
例如

public class Fruit { 
  private String name; 
  private int imageId; 

  public Fruit(String name, int imageId) {
    this.name = name; 
    this.imageId = imageId; 
  }

  //生成各属性的getter方法 
  public String getName() { 
    return name; 
  } 
  public int getImageId() {
     return imageId; 
  }
}

3.创建一个自定义的适配器继承ArrayAdapter，并将泛型指定为第2步的实体类。
例如

public class FruitAdapter extends ArrayAdapter { 

  private int resourceId;

  //构造函数传入context、item布局文件textViewResouId、数据对象objects 
  public FruitAdapter(Context context, int textViewResourceId, List objects) { 

    super(context, textViewResourceId, objects); 
    resourceId = textViewResourceId; 
}

  //复写getView将数据显示到布局上并将view返回 
  @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 =LayoutInflater.from(getContext()).inflate(resourceId,null); 
    ImageView fruitImage = (ImageView)view.findViewById(R.id.fruit_image); 
    TextView fruitName = (TextView)view.findViewById(R.id.fruit_name); 
    fruitImage.setImageResource(fruit.getImageId()); 
    fruitName.setText(fruit.getName()); retrun view;
   }
}

为了优化ListView，可以将第3步的代码修改成下面的例子

public class FruitAdapter extends ArrayAdapter { 
…… 
  @Override 
  public View getView(int position, View convertView, ViewGroup parent) {  
    Fruit fruit = getItem(position); 
    View view;
    ViewHolder viewHolder; 
    if (convertView == null) {
      view=LayoutInflater.from(getContext()).inflate(resourceId,null);  
      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; 
  }
}

4.在MainActivity为ListView设置Adapter

public class MainActivity extends Activity{  
  private List fruitList = new ArrayList(); 
  @Override 
  protected void onCreate(Bundle savedInstanceState){ 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    initFruits();//初始化水果数据将数据保存到fruitList，具体函数就不写了 

    //实例化Adapter 
    FruitAdapter adapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList); 
    ListView listView = (ListView) findViewById(R.id.list_view); 
    //为listView设置adapter 
    listView.setAdapter(adapter); 
  }
}