public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder> {
   //定义集合
  private List<Fruit> mFruitList;

  //利用构造器传入数据
  public FruitAdapter(List<Fruit> FruitList) {
    this.mFruitList = FruitList;
  }

  //创建ViewHolder的实例
  // ①onCreateViewHolder()用于创建ViewHolder实例，并把加载的布局传入到构造函数
  @Override
  public FruitAdapet.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    //由于ViewHolder构造器需要传入子项布局View对象，因此需要实例化子项布局
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.activity_fruit, parent, false);
    //创建ViewHolder对象
    ViewHolder viewHolder = new ViewHolder(view);
    //返回值
    return viewHolder;

  }

  //②onBindViewHolder()用于对RecyclerView子项的数据进行赋值，会在每个子项被滚动到屏幕内的时候执行
  @Override
  public void onBindViewHolder(final FruitAdapet.ViewHolder holder, int position) {
    //从集合中把水果对象拿出来
    Fruit fruit = mFruitList.get(position);
    //调用holder.ImageView对象设置图片
    holder.imageView.setImageResource(fruit.getImageId());
    //调用holder.TextView对象设置文字
    holder.textView.setText(fruit.getName());

  }

  //③getItemCount()用于知道RecyclerView有多少子项
  @Override
  public int getItemCount() {

    return mFruitList.size();
  }

  //创建ViewHolder继承RecyclerView.ViewHolder
  class ViewHolder extends RecyclerView.ViewHolder {
    ImageView imageView;
    TextView textView;


    //重写ViewHolder
    public ViewHolder(View itemView) {
      super(itemView);
      //通过View对象的findViewById方法获取到子项布局的控件保存在成员变量当中
      imageView = (ImageView) itemView.findViewById(R.id.imageView);

      textView = (TextView) itemView.findViewById(R.id.textView);
    }
  }
}

public class MainActivity extends AppCompatActivity {
  private List<Fruit> fruitList;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    //第三步：定义数据源，单独利用一个方法
    fruitData();

    //第四步：创建适配器
    FruitAdapet adapet = new FruitAdapet(fruitList);

    //第五步：找布局控件
    RecyclerView recyclerView= (RecyclerView) findViewById(R.id.recyclerView);

    //第六步：通过setLayoutManager()为RecylerView设置布局管理器
    //设置为垂直方向
    //水平方向的参数为：(this,LinearLayoutManager.HORIZONTAL, false);
    LinearLayoutManager linearLayoutManager=new LinearLayoutManager(this,
        LinearLayoutManager.VERTICAL,false);
    recyclerView.setLayoutManager(linearLayoutManager);

    //第七步：设置适配器
    recyclerView.setAdapter(adapet);
  }

  public void fruitData() {
    //创建一个集合保存数据
    fruitList = new ArrayList<>();
    //图片我就用了几张，然后让他循环变换而已，小伙伴可以自己增加各式的图片
    Fruit apple = new Fruit("苹果", R.drawable.apple);
    fruitList.add(apple);
    Fruit banana = new Fruit("香蕉", R.drawable.banana);
    fruitList.add(banana);
    Fruit apple1 = new Fruit("苹果", R.drawable.apple);
    fruitList.add(apple);
    Fruit banana1 = new Fruit("香蕉", R.drawable.banana);
    fruitList.add(banana);
    Fruit apple2 = new Fruit("苹果", R.drawable.apple);
    fruitList.add(apple);
    Fruit banana2 = new Fruit("香蕉", R.drawable.banana);
    fruitList.add(banana);
    Fruit apple3 = new Fruit("苹果", R.drawable.apple);
    fruitList.add(apple);
    Fruit banana3 = new Fruit("香蕉", R.drawable.banana);
    fruitList.add(banana);
    Fruit apple4 = new Fruit("苹果", R.drawable.apple);
    fruitList.add(apple);
    Fruit banana4 = new Fruit("香蕉", R.drawable.banana);
    fruitList.add(banana);
  }
}

//第一个参数用于指定布局的列数
//第二个参数用于指定布局的排列方向
   StaggeredGridLayoutManager layoutManager=new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.VERTICAL);
 recyclerView.setLayoutManager(layoutManager);