最常用的组件ListView

最常用的组件之一ListView

1. 最简单的使用方法–只显示文本数据

在Strings.xml中添加一组String-array 列表

  <string-array name="items"> //定义数据列表名为items
    <item >第一条数据</item>
    <item >我是第二条 </item>
    <item >我叫黄干</item>
    <item >ListView列表</item>              
</string-array>

Layout页面插入一个ListView

<ListView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:id="@+id/list_view" 
  android:entries="@array/items"  /> //引用名为items的数据列表

效果图

2. 设置ListView的点击事件

给ListView设置setOnItemClickListener

  listView = (ListView)findViewById(R.id.listView1);
   listView.setOnItemClickListener(new OnItemClickListener() {
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,long arg3) {

        //上面的arg2参数比较常用，用来获取点击的是哪一个Item,0是第一个
       Toast.makeText(getApplicationContext(), "点击了第"+arg2+"条", Toast.LENGTH_SHORT).show();

        }
      }
    });

效果图

重点：ListView ,适配器 和java Bean 结

使用ArrayAdapter,共三个Class类Animals.java, AnimalAdapter.java, MainActivity.java

• 模型层 Animals.java

  public class Animals {
  private String name;
  private int imageId;
  
  public Animals(String name, int imageId) {
  this.name = name;
  this.imageId = imageId;
  }
  public String getName() {
  return name;
  }
  public int getImageId() {
  return imageId;
  }   }
  

• 适配器类AnimalAdapter.java

  public class AnimalAdapter extends ArrayAdapter<Animals> {
    private int resourceId;
   public AnimalAdapter(Context context, int resource,List<Animals> objects) {
   super(context, resource,objects);
   resourceId = resource;
   }
   //ArrayAdapter需要重写的方法
   public View getView(int position,View convertView,ViewGroup parent){
   //给模型层提供ListView的位置
   Animals animals = getItem(position);
   //************
   //☆☆ListView的优化
   View view; 
   if(convertView == null){
   //设置视图接口
   view = LayoutInflater.from(getContext()).inflate(resourceId, null);        
   }else{ view = convertView;}
   ImageView animalImage = (ImageView) view.findViewById(R.id.animals_image);
   TextView animalName = (TextView) view.findViewById(R.id.aniamls_name);
  animalImage.setImageResource(animals.getImageId());
  animalName.setText(animals.getName());
  //************
  //☆☆☆设置列表内的点击事件
  animalImage.setOnClickListener(new OnClickListener() {  
  public void onClick(View v) {
      Toast.makeText(getContext(), "阿里符合贷款来开发的", Toast.LENGTH_SHORT).show();
  }
  });
  return view;    
  }
  }
  

• MainActivity.java

  public class MainActivity extends Activity {
  private List<Animals> animalList = new ArrayList<Animals>();
  
  protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  initAnimals();
  AnimalAdapter adapter = new AnimalAdapter(MainActivity.this, R.layout.animals_item,animalList);
  ListView listview = (ListView)findViewById(R.id.list_view);
  listview.setAdapter(adapter);
  listview.setOnItemClickListener(new OnItemClickListener() {
      @Override
      public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
              long arg3) {
          //☆ 获取点击的位置，并从位置获取其数据        
          Animals animals = animalList.get(arg2);
          Toast.makeText(MainActivity.this, animals.getName(),
          Toast.LENGTH_SHORT).show();
      }
  });         
  }  
  //给数据层提供数据
  private void initAnimals() {
  Animals Tiger = new Animals("Tiger", R.drawable.ddd);
  animalList.add(Tiger);
  Animals Lion = new Animals("Lion", R.drawable.fff);
  animalList.add(Lion);
  Animals Dog = new Animals("Dog", R.drawable.ggg);
  animalList.add(Dog);
  }   }
  

示例：点击列表条

点击单条列表左侧的图片