java 8 List常用操作

1.以某个属性分组

Map<String,List<User>> map= userList.stream().collect(Collectors.groupingBy(User::getName));

2.获取集合中的某个属性转为集合

pictureList.stream().map(Picture::getSrc).collect(Collectors.toList());

3.根据集合中的某个属性进行升序重排 asc

roomList.stream().sorted(Comparator.comparing(Room::getAvgPrice)).collect(Collectors.toList());

4.根据集合中的某个属性进行降序重排 desc

roomList.stream().sorted(Comparator.comparing(Room::getAvgPrice).reversed()).collect(Collectors.toList());

5.集合中的属性去重

rpTags.stream().distinct().collect(Collectors.toList());

6.根据集合中的某个属性过滤并获取第一个

benefitList.stream().filter(benefit -> benefit.getId() == 1 || benefit.getId() == 20 || benefit.getId() == 26 || benefit.getId() == 89) .findFirst().orElse(null);

7.根据集合中的属性转换为键值对Map

getModule().stream().collect(Collectors.toMap(RateplanDO::getRateplanCode, rateplanDO -> rateplanDO));

8.获取集合中某个最大值的int数据

partnerCityHotelDOList.stream().mapToInt(PartnerCityHotelDO::getId).max().orElse(-1);

9.提取集合中对象的某个属性转化List

partnerCityHotelDOList.stream().map(PartnerCityHotelDO::getId).collect(Collectors.toList());

10.Map转List

List<ImApplyMall> imApplyMallList = map.stream().map(o -> new ImApplyMall()).collect(Collectors.toList());

新能源吧