Stream流多字段排序

今天做了stream流多字段排序出现空指针异常

解决办法：Comparator.nullsLast(String::compareTo)

        List<DataSumDemo> dataSumDemoOne = dataSumDemoListOne.stream()
                .sorted(Comparator.comparing(DataSumDemo::getCityName, Comparator.nullsLast(String::compareTo))
                .thenComparing(DataSumDemo::getRegionName, Comparator.nullsLast(String::compareTo)))
                .collect(Collectors.toList());