java lambda表达式排序list object类型

@Test
void testSort() {
      ArrayList<User> users = new ArrayList<>();
      users.add(new User("huangqg", 50000));
       users.add(new User("songyc", 35000));
       users.add( new User("hanxu", 42000));

       // core
       users.sort((User u1, User u2) -> u2.getSalary() - u1.getSalary());

       System.out.println(users);
       // [User{name='huangqg', salary=50000}, User{name='hanxu', salary=42000}, User{name='songyc', salary=35000}]
  }

class User {
    private String name;

    public String getName() {
        return name;
    }

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

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

    private int salary;

    public User(String name, int salary) {
        this.name = name;
        this.salary = salary;
    }

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