Java ListのSort

import java.util.List;
import java.util.ArrayList;

public class SortTest1 {

    public static void main(String[] args) {

        List<Person> people = new ArrayList<>();
        people.add(new Person("Alice", 30));
        people.add(new Person("Bob", 19));
        people.add(new Person("Ronald", 40));
        people.add(new Person("Jimi", 27));
        people.add(new Person("Suzan", 60));
        people.add(new Person("Jeff", 80));
        people.add(new Person("Maria", 52));

        // sort by name
        people.sort((p1, p2)->p1.getName().compareTo(p2.getName()));
        System.out.println(people);
        // [name:Alice age:30, name:Bob age:19, name:Jeff age:80, name:Jimi age:27, name:Maria age:52, name:Ronald age:40, name:Suzan age:60]

        // sort by age
        people.sort((p1, p2)->p1.getAge().compareTo(p2.getAge()));
        System.out.println(people);
        // [name:Bob age:19, name:Jimi age:27, name:Alice age:30, name:Ronald age:40, name:Maria age:52, name:Suzan age:60, name:Jeff age:80]

    }
}

class Person {

    private String name;
    private Integer age;

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

    public Integer getAge() {
        return age;
    }

    public String getName() {
        return name;
    }

    public String toString() {
        return "name:" + name + " age:" + age;
    }