慕课在线编辑器

代码提交代码

import java.util.Optional;

public class OptionalDemo2 {

static class Category {
        private String name;

public Category(String name) {
            this.name = name;
        }

public String getName() {
            return name;
        }

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

@Override
        public String toString() {
            return "Category{" +
                    "name='" + name + '\'' +
                    '}';
        }
    }

static class Goods {
        private String name;

private Category category;

public Goods() {

}

public Goods(String name, Category category) {
            this.name = name;
            this.category = category;
        }

public String getName() {
            return name;
        }

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

public Category getCategory() {
            return category;
        }

public void setCategory(Category category) {
            this.category = category;
        }

@Override
        public String toString() {
            return "Good{" +
                    "name='" + name + '\'' +
                    ", category=" + category +
                    '}';
        }
    }

/**
     * 获取商品的分类名称
     * @param goods 商品
     * @return 分类名称
     */
    static String getGoodsCategoryName(Goods goods) {
        return goods.getCategory().getName();
    }

public static void main(String[] args) {
        // 实例化一个商品类
        Goods goods = new Goods();
        // 获取商品的分类名称
        String categoryName = getGoodsCategoryName(goods);
        System.out.println(categoryName);
    }
}

运行结果