移动技术开发：RecyclerView瀑布流水果列表

1 实验名称

RecyclerView瀑布流水果列表

2 实验目的

掌握RecyclerView控件的实现方法和基本应用

3 实验源代码

布局文件代码：

activity_main：

java 复制代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</LinearLayout>

fruit_item：

java 复制代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <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"
        />
</LinearLayout>

Java代码：

MainActivity .java：

java 复制代码

public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitLists = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //初始化水果列表数据
        initFruits();
        //创建循环列表对象
        RecyclerView recycler_view = findViewById(R.id.recycler_view);
        //创建一个线性布局管理器对象
        //LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        //设置线性布局管理器的管理方向为水平管理
        //linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        //设置循环列表的布局管理器
        //创建一个3列垂直的瀑布流布局管理器对象
        StaggeredGridLayoutManager staggeredGridLayoutManager =
                new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL);
        recycler_view.setLayoutManager(staggeredGridLayoutManager);
        //创建列表数据适配器对象并把数据源关联上
        FruitAdapter fruitAdapter = new FruitAdapter(fruitLists);
        //让循环列表使用适配器对象
        recycler_view.setAdapter(fruitAdapter);
    }

    private void initFruits(){
        for (int i = 0; i < 2; i++) {
            Fruit apple = new Fruit(getRandomLengthName("Apple"), R.drawable.apple_pic);
            fruitLists.add(apple);
            Fruit banana = new Fruit(getRandomLengthName("Banana"), R.drawable.banana_pic);
            fruitLists.add(banana);
            Fruit orange = new Fruit(getRandomLengthName("Orange"), R.drawable.orange_pic);
            fruitLists.add(orange);
            Fruit watermelon = new Fruit(getRandomLengthName("Watermelon"), R.drawable.watermelon_pic);
            fruitLists.add(watermelon);
            Fruit pear = new Fruit(getRandomLengthName("Pear"), R.drawable.pear_pic);
            fruitLists.add(pear);
            Fruit grape = new Fruit(getRandomLengthName("Grape"), R.drawable.grape_pic);
            fruitLists.add(grape);
            Fruit pineapple = new Fruit(getRandomLengthName("Pineapple"), R.drawable.pineapple_pic);
            fruitLists.add(pineapple);
            Fruit strawberry = new Fruit(getRandomLengthName("Strawberry"), R.drawable.strawberry_pic);
            fruitLists.add(strawberry);
            Fruit cherry = new Fruit(getRandomLengthName("Cherry"), R.drawable.cherry_pic);
            fruitLists.add(cherry);
            Fruit mango = new Fruit(getRandomLengthName("Mango"), R.drawable.mango_pic);
            fruitLists.add(mango);
        }
    }

    private String getRandomLengthName(String name){
        Random random = new Random();
        int length = random.nextInt(20);
        StringBuilder stringBuilder = new StringBuilder();
        for(int i=0;i<length;i++){
            stringBuilder.append(name);
        }
        return stringBuilder.toString();
    }
}

FruitAdapter.java：

java 复制代码

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
    private List<Fruit> fruitLists = null;//子项水果数据源列表

    public FruitAdapter(List<Fruit> fruitLists) {
        this.fruitLists = fruitLists;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //得到子项布局的视图
        View itemView = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.fruit_item,parent,false);
        ViewHolder viewHolder = new ViewHolder(itemView);
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        Fruit fruit = fruitLists.get(position);//根据位置得到一个水果对象
        //将水果图片放到子项视图持有器的ImageView中
        holder.fruit_image.setImageResource(fruit.getImageId());
        //将水果名字放到子项视图持有器的TextView中
        holder.fruit_name.setText(fruit.getName());
    }

    @Override
    public int getItemCount() {
        return fruitLists.size();
    }

    //列表子项的视图持有器
    static class ViewHolder extends RecyclerView.ViewHolder{

        ImageView fruit_image;
        TextView fruit_name;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            fruit_image = itemView.findViewById(R.id.fruit_image);
            fruit_name = itemView.findViewById(R.id.fruit_name);
        }
    }
}

Fruit.java：

java 复制代码

//自定义数据源类
public class Fruit {

    private String name;
    private int imageId;//水果图片ID号

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getImageId() {
        return imageId;
    }

    public void setImageId(int imageId) {
        this.imageId = imageId;
    }
}

4 实验运行结果图

5 实验总结

先写布局文件，两个布局文件，分别是activity_main.xml布局文件和fruit_item.xml布局文件。在activity_main.xml布局文件中，设置了一个瀑布流列表；而fruit_item.xml布局文件中在列表中插入图片和文本框。

写完布局文件开始写Java代码，初始化水果列表数据，创建循环列表对象，创建一个三列垂直的瀑布流布局管理器对象，创建列表数据适配器对象并把数据源关联上，让循环列表适用适配器对象，将水果图片和名字放到子项视图持有器中。