取两个集合的交集

 List<Long> departmentUserNos = departmentVOList.stream().map(UserDepartmentVO::getUserNo).collect(toList());
 List<Long> postUserNos = uo.stream().map(UserPostVO::getUserNo).collect(toList());
              
  // 取出交集数据
 List<Long> collect = departmentUserNos.stream().filter(postUserNos::contains).collect(toList());

//取差集
departmentUserNos.removeAll(collect )--->集合中剩余的为departmentUserNos独有的

同理：
postUserNos.removeAll(collect ) --->集合中剩余的为postUserNos独有的