Android开发学习记录--ListView使用

Posted 2021-02-14 孟庆淋

1.ListView的简单使用

首先建立一个新的项目，在xml文件中添加ListView控件，如下所示：

<ListView
    android:id="@+id/list_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</ListView>
接下来修改MainActivity中的代码：

public class MainActivity extends AppCompatActivity {
    private String[] data={"Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango","Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango"};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(MainActivity.this,android.R.layout.simple_list_item_1,data);
        ListView listView=(ListView) findViewById(R.id.list_view);
        listView.setAdapter(adapter);
    }
}
将数据存储在数组中，借助ArrayAdapter适配器传递数据给ListView，最后调用setAdapter()方法，将适配器对象传递出去，关联建立完成。

2.定制ListView的界面

定义一个新的实体类，作为ListView适配器的适配类型。

public class Fruit {
    private String name;//水果名字
    private int imageId;//水果对应图片id
    public Fruit(String name,int imageId){
        this.name=name;
        this.imageId=imageId;
    }

    public int getImageId() {
        return imageId;
    }

    public java.lang.String getName() {
        return name;
    }
}
指定一个自定义布局，代码如下

<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>
其中控件ImageView用来显示水果图片，TextView用来显示水果名称。
接下来自定义一个适配器，继承自ArrayAdapter：
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 position, View convertView, ViewGroup parent){
        Fruit fruit=getItem(position);
        View view= LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
        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());
        return view;
    }
}
FruitAdapter重写了父类的一组构造函数，用于将上下文、ListView子项布局的id和数据都传递进来。在重写的getView()方法中，首先通过getItem()方法得到当前的Fruit实例，然后使用LayoutInflater来为这个子项加载我们传入的数据。
接下来对MainActivity进行修改：

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);
        initFruits();
        FruitAdapter adapter=new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitlist);
        ListView listView=(ListView)findViewById(R.id.list_view);
        listView.setAdapter(adapter);
    }
    private void initFruits(){
        for(int i=0;i<2;i++)
        {
            Fruit apple=new Fruit("Apple",R.drawable.fruit_1);
            fruitlist.add(apple);
            Fruit banana=new Fruit("banana",R.drawable.fruit_2);
            fruitlist.add(banana);
            Fruit orange=new Fruit("orange",R.drawable.fruit_1);
            fruitlist.add(orange);
            Fruit watermelon=new Fruit("watermelon",R.drawable.fruit_1);
            fruitlist.add(watermelon);
            Fruit pear=new Fruit("pear",R.drawable.fruit_2);
            fruitlist.add(pear);
        }
    }
}

运行程序，效果如下：

3.ListView的点击事件

在MainActivity中添加如下代码（为ListView注册一个监听器），点击水果时可以显示该水果名：

listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
        Fruit fruit=fruitlist.get(position);
        Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show();
    }
});
运行程序，效果如下：