public class Test {

    public static void main(String[] args) {
        Product product1 = new Product("張三", "20", 3);
        Product product2 = new Product("張三", "20", 3);
        Product product3 = new Product("張三", "20", 3);
        Product product4 = new Product("張三", "20", 3);
        Product product5 = new Product("張三", "20", 3);

        Product product  = new Product("張三1", "22", 1);
        Product product6 = new Product("張三2", "25", 1);
        Product product7 = new Product("張三2", "24", 1);
        Product product8 = new Product("張三1", "22", 1);
        Product product9 = new Product("張三1", "22", 1);

        List<Product> products = new ArrayList<>();
        products.add(product1);
        products.add(product2);
        products.add(product3);
        products.add(product4);
        products.add(product5);
        products.add(product);
        products.add(product6);
        products.add(product7);
        products.add(product8);
        products.add(product9);

        Map<String, Map<String, List<Product>>> collect = products.stream().collect(Collectors.groupingBy(Product::getName,Collectors.groupingBy(Product::getAge)));
        int size = collect.size();
        int size1 = collect.values().size();
        collect.values().forEach(m1 ->{
            m1.values().forEach(m2 -> {
                int size2 = m2.size();
                for (Product product10 : m2) {
                    System.out.println(product10.getName()+product10.getAge()+product10.getNum()+"----"+size2);
                }
            });
        });
    }
}