Android学习——RecyclerView

实现横向滚动和瀑布流布局

横向滚动：

修改布局fruit_item.xml，将元素改为垂直排列

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_gravity="center_horizontal" />

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginTop="10dp" />
</LinearLayout>

修改MainActivity，调用LinearLayoutManager的setOrientation()方法来设置布局的排列方向，默认是纵向，传入LinearLayoutManager.HORIZONTAL表示让布局横向排列

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();
        RecyclerView recyclerView = findViewById(R.id.relative_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }
    private  void initFruits(){
        for (int i = 0;i<2;i++){
            Fruit apple = new Fruit("Apple",R.drawable.apple);
            fruitList.add(apple);
            Fruit banner = new Fruit("Banner",R.drawable.banner);
            fruitList.add(banner);
            Fruit orange = new Fruit("Orange",R.drawable.orange);
            fruitList.add(orange);
            Fruit watermelon = new Fruit("Watermelon",R.drawable.watermelon);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear",R.drawable.pear);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape",R.drawable.grape);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple",R.drawable.pineapple);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit("Strawberry",R.drawable.strawberry);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit("Cherry",R.drawable.cherry);
            fruitList.add(cherry);
            Fruit mango = new Fruit("Mango",R.drawable.mango);
            fruitList.add(mango);

        }
    }
}

瀑布流布局

修改fruit_item布局，使用layout_margin属性让子项之间互留间距，TextView对其属性改为居左对齐

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical"
    android:layout_margin="5dp"
    >

    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_gravity="center_horizontal" />

    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="left"
        android:layout_marginTop="10dp" />
</LinearLayout>

修改MainActivity

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();
        RecyclerView recyclerView = findViewById(R.id.relative_view);
        //创建StaggeredGridLayoutManager实例。StaggeredGridLayoutManager的构造函数接收两个参数，第一个是布局的列数，第二个是布局的排列方向，StaggeredGridLayoutManager.VERTICAL是让布局纵向排列
        StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL);
        //吧创建好的实例设置到RecyclerView中
        recyclerView.setLayoutManager(layoutManager);
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }
    private  void initFruits(){
        for (int i = 0;i<2;i++){
            Fruit apple = new Fruit(getRandomLengthName("Apple"),R.drawable.apple);
            fruitList.add(apple);
            Fruit banner = new Fruit(getRandomLengthName("Banner"),R.drawable.banner);
            fruitList.add(banner);
            Fruit orange = new Fruit(getRandomLengthName("Orange"),R.drawable.orange);
            fruitList.add(orange);
            Fruit watermelon = new Fruit(getRandomLengthName("Watermelon"),R.drawable.watermelon);
            fruitList.add(watermelon);
            Fruit pear = new Fruit(getRandomLengthName("Pear"),R.drawable.pear);
            fruitList.add(pear);
            Fruit grape = new Fruit(getRandomLengthName("Grape"),R.drawable.grape);
            fruitList.add(grape);
            Fruit pineapple = new Fruit(getRandomLengthName("Pineapple"),R.drawable.pineapple);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit(getRandomLengthName("Strawberry"),R.drawable.strawberry);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit(getRandomLengthName("Cherry"),R.drawable.cherry);
            fruitList.add(cherry);
            Fruit mango = new Fruit(getRandomLengthName("Mango"),R.drawable.mango);
            fruitList.add(mango);

        }
    }