listView 的用法

1.Fruit.class 定义为水果实体类

    

public 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;    }}

2.fruit_item 为listview的子项定义一个布局

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"              android:layout_width="match_parent"              android:layout_height="match_parent">      <ImageView          android:id="@+id/fruit_image"          android:layout_width="wrap_content"          android:layout_height="wrap_content"/>     <TextView         android:id="@+id/fruit_name"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_gravity="center_vertical"         android:layout_marginLeft="10dp"         /></LinearLayout>
3.FruitAdapter.class  定义一个自定义的适配器，并将泛型指定为Fruit类
  
/** *  自定义的适配器*/public class FruitAdapter extends ArrayAdapter<Fruit> {     private int resourceId;     public FruitAdapter(Context context,int textViewResourceId,                         List<Fruit> objects)    {        super(context,textViewResourceId,objects);        resourceId = textViewResourceId;    }    @Override    public View getView(int postion, View convertView, ViewGroup parent )    {        Fruit fruit = getItem(postion);//获取当前的的实例        View view;        ViewHolder  viewHolder;        if (convertView ==null)        {            view =  LayoutInflater.from(getContext()).inflate(resourceId,parent,false); //false表不增父布局            viewHolder = new ViewHolder();            viewHolder.fruitImageId = (ImageView)view.findViewById(R.id.fruit_image);            viewHolder.fruitName = (TextView) view.findViewById(R.id.fruit_name);            view.setTag(viewHolder);//将viewHolder储存在view中        }        else        {            view = convertView;            viewHolder = (ViewHolder) view.getTag();//重新获取ViewHolder;        }        viewHolder.fruitImageId.setImageResource(fruit.getImageId());        viewHolder.fruitName.setText(fruit.getName());        return view;    }    class ViewHolder{        ImageView fruitImageId;        TextView  fruitName;    }}
  
4.MainActivity.java 主活动
  
public class MainActivity extends AppCompatActivity { private List<Fruit> fruitList = new ArrayList<>();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initFruit();       FruitAdapter adapter =  new FruitAdapter(MainActivity.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(MainActivity.this, fruit.getName(), Toast.LENGTH_SHORT).show();            }        });    }    public void initFruit()    {        for (int i =0;i< 4 ; i ++ ){      Fruit apple =  new Fruit("apple",R.drawable.apple);        fruitList.add(apple);        Fruit banana =  new Fruit("banana",R.drawable.banana);        fruitList.add(banana);        Fruit orange =  new Fruit("orange",R.drawable.orange);        fruitList.add(orange);        Fruit pear =  new Fruit("pear",R.drawable.pear);        fruitList.add(pear);        Fruit watermelon =  new Fruit("pear",R.drawable.watermelon);        fruitList.add(watermelon);        }    }}

6.activity_layout.xml 主布局文件

<LinearLayout    android:id="@+id/activity_main"    xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context="com.sh.customlistviewtest.MainActivity">    <ListView        android:id="@+id/list_view"        android:layout_width="match_parent"        android:layout_height="wrap_content">    </ListView></LinearLayout>