Java stream判斷列表是否包含某幾個元素
(需求經過修改過)判斷一個profile是否包含PROFILE-IN-A和PROFILE-IN-B且都是Enable=1打勾的.
既然已經JDK8了,那就用lambda
吧,如果是foreach可能比較難處理,用stream
的filter
則可以這樣做.
核心代碼可以這麼寫
int intCheck = profileServiceDtoList.stream().filter(e ->
"1".equals(e.getEnable())
&&(("PROFILE-IN-MOSHOW".equals(e.getServiceIdentifier()))||("PROFILE-IN-ADC".equals(e.getServiceIdentifier())))
).collect(Collectors.toList()).size();
代碼SHOW
- 新建三個不同類型的profile,其中兩個是要判斷的,一個是
干擾
的. - 通過
steam
進行filter
,找出是否包含這兩個元素(相當於把要判斷的元素過濾進去) - 判斷list的
size
大小(intCheck>1找到兩個則代表同時出現)
public static void main(String[] args) {
List<ProfileServiceDto> profileServiceDtoList= new ArrayList<>(3);
ProfileServiceDto profileService1 = new ProfileServiceDto();
profileService1.setServiceId(1001L);
profileService1.setServiceIdentifier("PROFILE-IN-MOSHOW");
profileService1.setEnable("1");
profileServiceDtoList.add(profileService1);
ProfileServiceDto profileService2 = new ProfileServiceDto();
profileService2.setServiceId(1002L);
profileService2.setServiceIdentifier("PROFILE-IN-ADC");
profileService2.setEnable("1");
profileServiceDtoList.add(profileService2);
ProfileServiceDto profileService3 = new ProfileServiceDto();
profileService3.setServiceId(1003L);
profileService3.setServiceIdentifier("PROFILE-XXX-ABC");
profileService3.setEnable("1");
profileServiceDtoList.add(profileService3);
int intCheck = profileServiceDtoList.stream().filter(e ->
"1".equals(e.getEnable())&&(("PROFILE-IN-MOSHOW".equals(e.getServiceIdentifier()))||("PROFILE-IN-ADC".equals(e.getServiceIdentifier())))
).collect(Collectors.toList()).size();
System.out.println("intCheck->"+intCheck);
if(intCheck>1){
System.error.println("In one profile, cannot contain two more PROFILE-IN profile.");
}
}
Java stream判斷列表是否包含重複元素
思路是通過一個distinct的list,然後跟原先的list來判斷大小,如果不一致(原先list.size>distinctList.size)則表示有重複元素
//profileServiceDtoList路上,不累贅
//多了一個profileService1.setGroupId("A");profileService1.setGroupId("B");profileService3.setGroupId("A");
List<String> groupList = new ArrayList<>(4);
profileServiceDtoList.stream().forEach(e -> {
if ("Y".equals(e.getEnable()) && StringUtils.isNotEmpty(e.getGroupId())) {
groupList.add(e.getGroupId());
}
});
int distinctGroupSize = groupList.stream().distinct().collect(Collectors.toList()).size();
if (groupList.size() > distinctGroupSize) {
throw new ValidationException("100001","In one profile, the services with the same groupId cannot co-exist.");
}