public class StreamPractice {
    Child liMing = new Child("LiMing", "Shanghai");
    Child yeWen = new Child("IpMan", "FoShan");
    Child liLi = new Child("LiLi", "Shanghai");
    Child liChao = new Child("LiChao", "Shanghai");

    List<Toy> toys = Arrays.asList(
            new Toy(liChao, LocalDate.of(2021, 1, 1), 50),
            new Toy(yeWen, LocalDate.of(2021, 2, 5), 60),
            new Toy(liLi, LocalDate.of(2020, 7, 12), 150),
            new Toy(liMing, LocalDate.of(2018, 10, 3), 1000),
            new Toy(liChao, LocalDate.of(2021, 2, 8), 20),
            new Toy(yeWen, LocalDate.of(2021, 4, 5), 73)
            );

    //找出所有玩具，并按照玩具的价格从低到高排列
    public void listToySortPrice() {
        List<Toy> toyList = toys.stream().sorted((o1, o2) -> o1.getPrice() >= o2.getPrice() ? 1 : -1).filter(x -> x.getBuyTime().contains("2021")).collect(Collectors.toList());
        toyList.forEach(System.out::println);
    }

    //找出孩子们所属的城市
    public void listCities() {
        List<String> cities = toys.stream().map(x -> x.getChild().getCity()).distinct().collect(Collectors.toList());
        cities.forEach(System.out::println);
    }

    //找出所有来自于Shanghai的孩子，并按照姓名排序
    public void listChildFromShanghai() {
        List<Child> childList = toys.stream().map(Toy::getChild).filter(x -> "Shanghai".equals(x.getCity())).distinct().sorted(Comparator.comparing(Child::getCity)).collect(Collectors.toList());
        childList.forEach(System.out::println);
    }

    //返回所有孩子的名字字符串，并按照字母顺序排序
    public void listChildNameSortedByWord() {
        List<String> childNameList = toys.stream().map(x -> x.getChild().getName()).distinct().sorted().collect(Collectors.toList());
        childNameList.forEach(System.out::println);
    }

    public static void main(String[] args) {
        StreamPractice sp = new StreamPractice();
        sp.listToySortPrice();
        sp.listCities();
        sp.listChildFromShanghai();
        sp.listChildNameSortedByWord();
    }
}

class Child {
    private final String name;

    private final String city;

    public Child(String name, String city) {
        this.name = name;
        this.city = city;
    }

    public String getName() {
        return name;
    }

    public String getCity() {
        return city;
    }

    public String toString() {
        return "Child: " + this.name + " in " + this.city;
    }
}

class Toy {
    private final Child child;
    private final LocalDate buyTime;
    private final int price;

    public Toy(Child child, LocalDate buyTime, int price) {
        this.child = child;
        this.buyTime = buyTime;
        this.price = price;
    }

    public Child getChild() {
        return this.child;
    }

    public String getBuyTime() {
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        return buyTime.format(formatter);
    }

    public int getPrice() {
        return this.price;
    }

    public String toString() {
        return "{" + this.child + ", " +
                "buy time: " + this.buyTime + ", " +
                "price: " + this.price + " }";
    }
}