这个顺序是从右边往左边
Map<Date, List<Map<String, Object>>> dataMap = dayBeforeCostList == null && dayBeforeCostList.size() == 0 ? null : dayBeforeCostList.stream().collect
(Collectors.groupingBy(e -> (Date) e.get("PDATE")));
Java：符号优先级的排列顺序
https://blog.csdn.net/weixin_64145253/article/details/121986025
标签：dayBeforeCostList,顺序,优先级,等于号,java,null From： https://www.cnblogs.com/rapper-start/p/17087261.html