import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.List;

public class User {

    public static void main(String[] args) {

        List<User> list = new ArrayList<>();

        list.add(new User("张三",18));

        list.add(new User("诸葛亮",69));

        list.add(new User("孙悟空",500));

        list.add(new User("周杰伦",45));

        list.add(new User("郭德纲",60));

        list.add(new User("秦始皇",5000));

        System.out.println("排序前：");

        System.out.println(list);

        Collections.sort(list, new Comparator<User>() {

            @Override

            public int compare(User o1, User o2) {

                int age1 = o1.getAge();

                int age2 = o2.getAge();

                if (age1 == age2) {

                    return 0;

                }else {

                    // 从小到大

                    return age1 > age2 ? 1 : -1 ;

                    // 如果需要从大到小，可以将return的值反过来即可

                }

            }

        });

        System.out.println("排序后：");

        System.out.println(list);

    }

        private String name;

        private int age;

        public String getName() {

            return name;

        }

        public void setName(String name) {

            this.name = name;

        }

        public int getAge() {

            return age;

        }

        public void setAge(int age) {

            this.age = age;

        }

        public User(String name, int age) {

            super();

            this.name = name;

            this.age = age;

        }

        public User() {

            super();

        }

        @Override

        public String toString() {

            return "User [name=" + name + ", age=" + age + "]";

        }

}