java---排序

@Data
@AllArgsConstructor
class Person {
    private String name;
    private Integer age;
    private Integer score;
}

• sort排序能改变原集合，
• stream().sorted()的返回值才是排序后的集合，原集合不变
• Comparator.nullsLast遇到排序的字段为null时不报错且至于最后位置
• Comparator.reverseOrder():倒序排序，Comparator.naturalOrder():升序排序
• thenComparing 多个字段排序

@Test
public void testSort() {
    List<Person> persons = new ArrayList<>();
    persons.add(new Person("王xx", 90, 100));
    persons.add(new Person("张xx", null, 108));
    persons.add(new Person("李xx", 90, 120));
    persons.add(new Person("老虎", 90, 78));
    Comparator<Person> ageDesc = Comparator.comparing(Person::getAge, Comparator.nullsLast(Comparator.reverseOrder()));
    Comparator<Person> scoreDesc = Comparator.comparing(Person::getScore, Comparator.nullsLast(Comparator.naturalOrder()));
    persons.sort(ageDesc.thenComparing(scoreDesc));
    log.info("persons:{}", JSON.toJSONString(persons));
}