#275 Filtering and Sorting Persons and Children

The following class is given:

import java.util.List;
import java.util.stream.Collectors;

public class Main {

    public static void main(String[] args) {
        var personList = init();
        printList(personList);

    }

        private static void printList(List list) {
        System.out.println(list.stream()
            .map(Object::toString)
            .collect(Collectors.joining("\n")));
    }

        private static List<Person> init() {
        return List.of(
            new Main.Person("Alexey", List.of(
                new Main.Child("Albina", 3),
                new Child("Arseniy", 8),
                new Child("Alexander", 15))),
            new Main.Person("Grigory", List.of()),
            new Main.Person("Dmitry", List.of(
                new Main.Child("Darya", 1),
                new Child("Daniil", 5))),
            new Main.Person("Boris", List.of(
                new Main.Child("Bogdan", 9))),
            new Main.Person("Victoria", List.of(
                new Main.Child("Vladimir", 4),
                new Child("Varvara", 7),
                new Child("Valeria", 12))),
            new Main.Person("Elena", List.of(
                new Main.Child("Evgeny", 11))));
    }

    public static class Child {

        private String name;
        private Integer age;

        Child(String name, Integer age) {
            this.name = name;
            this.age = age;
        }

        public String getName() {
            return name;
        }

        public Integer getAge() {
            return age;
        }

        @Override
        public String toString() {
            return name + " - " + age;
        }

    }

    public static class Person {

        private String name;
        private List<Child> children;

        Person(String name, List<Child> children) {
            this.name = name;
            this.children = children;
        }

        public String getName() {
            return name;
        }

        public List<Child> getChildren() {
            return children;
        }

        @Override
        public String toString() {
            return name + ": " +
                children.stream()
                    .map(Object::toString)
                    .collect(Collectors.joining(", "));
        }
    }
}

Perform several operations on the List<Person>:

• remove persons who have fewer than two children;
• sort persons by the age of their youngest child;
• obtain a common List<Child>;
• sort children by name and age.