假设一个List中，存放的是一个User对象，User对象中有一个age属性，根据age排序：
使用list中自带的sort方法，里面自己重写compare方法，或者直接使用lambda表达式，如下

public class Test {

    @Data
    class User {
        private String name;
        private int age;

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

    public static void main(String[] args) {
        // 创建四个实例
        User userA = new Test().new User("吴俊", 30);
        User userB = new Test().new User("董浩", 25);
        User userC = new Test().new User("黄健雄", 27);
        User userD = new Test().new User("冯普超", 30);
        List<User> userList = Lists.newArrayList(userA, userB, userC, userD);

        System.out.println("排序前:");
        for (User item : userList) {
            System.out.println("name:" + item.getName() + ",age:" + item.getAge());
        }

        System.out.println("重写compare排序:");
        userList.sort(new Comparator<User>() {
            @Override
            public int compare(User o1, User o2) {
                if (o1.getAge() > o2.getAge()) return 1;
                return -1;
            }
        });
        for (User item : userList) {
            System.out.println("name:" + item.getName() + ",age:" + item.getAge());
        }

        System.out.println("排序前:");
        List<User> userList2 = Lists.newArrayList(userA, userB, userC, userD);
        for (User item : userList2) {
            System.out.println("name:" + item.getName() + ",age:" + item.getAge());
        }

        System.out.println("lambda表达式排序:");
        userList2.sort(Comparator.comparing(User::getAge));
        for (User item : userList) {
            System.out.println("name:" + item.getName() + ",age:" + item.getAge());
        }
    }
}

临时图片.png