Java stream判断列表是否包含某几个元素/重复元素

￡神魔★判官ぃ 2023-06-04 07:56 20阅读 0赞

## Java stream判断列表是否包含某几个元素 ##

(需求经过修改过)判断一个profile是否包含PROFILE-IN-A和PROFILE-IN-B且都是Enable=1打勾的.

既然已经JDK8了,那就用`lambda`吧,如果是foreach可能比较难处理,用`stream`的`filter`则可以这样做.  
核心代码可以这么写

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();

## 代码SHOW ##

1.  新建三个不同类型的profile,其中两个是要判断的,一个是`干扰`的.
2.  通过`steam`进行`filter`,找出是否包含这两个元素(相当于把要判断的元素过滤进去)
3.  判断list的`size`大小(intCheck>1找到两个则代表同时出现)

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判断列表是否包含重复元素 ##

思路是通过一个distinct的list,然后跟原先的list来判断大小,如果不一致(原先list.size>distinctList.size)则表示有重复元素

//profileServiceDtoList路上,不累赘
    		//多了一个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.");
            }