List集合内字段大小比较_list集合中判断大小的方法

重写compare方法的比较：
升序：
o1>o2,return 1 或 o1<o2,return -1
降序：
o1>o2,return -1 或 o1<o2,return 1

//实体类
static class User{
        private Integer age;
        private Integer score;
        @Override
        public String toString() {
            return "User{" +
                    "age=" + age +
                    ", score=" + score +
                    '}';
        }
        public Integer getAge() {
            return age;
        }
        public void setAge(Integer age) {
            this.age = age;
        }
        public Integer getScore() {
            return score;
        }
        public void setScore(Integer score) {
            this.score = score;
        }
    }
    //实现Comparator接口
    public static class ComparatorSort implements Comparator<User> {
        @Override
        public int compare(User o1, User o2) {
            if (o1.getAge() > o2.getAge()) {
                return 1;
            } else if (o1.getAge() < o2.getAge()) {
                return -1;
            } else {
            //当age相等时按照score排序
                if (o1.getScore() > o2.getScore()) {
                    return 1;
                } else {
                    return -1;
                }
            }
        }
    }
    //枚举插入数据
        public static void main(String[] args) {
            List<User> list = new ArrayList();
            User user1 = new User();
            user1.setAge(32);
            user1.setScore(456);
            list.add(user1);
            User user2 = new User();
            user2.setAge(15);
            user2.setScore(532);
            list.add(user2);
            User user3 = new User();
            user3.setAge(19);
            user3.setScore(234);
            list.add(user3);
            User user4 = new User();
            user4.setAge(32);
            user4.setScore(234);
            list.add(user4);
        }
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调用重写的compare方法

            //调用重写的compare方法排序
            Collections.sort(list, new ComparatorSort());
            //如果要对最终结果逆序排序，可以使用reverse
            Collections.reverse(list);
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使用stream排序
多条件使用：thenComparing进行排序

            //替换compare方法的排序，只对年龄排序
            list = list.stream().sorted(Comparator.comparing(User::getAge)).collect(Collectors.toList());
            
            //只对年龄排序,使用reversed倒序
            list = list.stream().
            sorted(Comparator.comparing(User::getAge).reversed()).collect(Collectors.toList());
            
            //年龄逆序，成绩顺序排列
            list = list.stream()
            .sorted(Comparator.comparing(User::getAge).reversed().thenComparing(User::getScore))
                    .collect(Collectors.toList());
                    
            //年龄和成绩逆序排列
             list = list.stream().sorted(Comparator.comparing(User::getAge)
                    .reversed()
                    .thenComparing(Comparator.comparing(User::getScore).reversed()))
            .collect(Collectors.toList());
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