list集合分组：根据对象某一属性分组

古城微笑少年丶 2023-06-17 06:53 21阅读 0赞

转自： [https://blog.csdn.net/weixin\_30416497/article/details/97049185][https_blog.csdn.net_weixin_30416497_article_details_97049185]

java 8 lambda表达式list操作分组、过滤、求和、最值、排序、去重:  [https://blog.csdn.net/gsls200808/article/details/86501905][https_blog.csdn.net_gsls200808_article_details_86501905]

jdk8 lambda表达式list操作分组、过滤、求和、最值、排序、去重:  [https://blog.csdn.net/qq\_43563538/article/details/97912937][https_blog.csdn.net_qq_43563538_article_details_97912937]

list通过里面对象的某个属性分组、分组求和、去重: [https://blog.csdn.net/CMEguagua/article/details/94552978][https_blog.csdn.net_CMEguagua_article_details_94552978]

list通过里面对象的某个属性分组或者分组汇总: [https://blog.csdn.net/Man20161217/article/details/82657698][https_blog.csdn.net_Man20161217_article_details_82657698]

原文链接：[http://www.cnblogs.com/move22/p/10429060.html][http_www.cnblogs.com_move22_p_10429060.html]

private Map<String, List<CreditContractSignSerial>> listGroup2MapTwo(List<CreditContractSignSerial> list) {
       Map<String, List<CreditContractSignSerial>> userSignSerialMap = Maps.newConcurrentMap();
       if (CollectionUtils.isNotEmpty(list)) {
          // 分组
          for (CreditContractSignSerial vo : list) {
             String transDate = new SimpleDateFormat("yyyyMMdd").format(vo.getCreateTime());
    
             List<CreditContractSignSerial> tempList = userSignSerialMap.get(transDate);
             /*如果取不到数据,那么直接new一个空的ArrayList**/
             if (tempList == null) {
                tempList = Lists.newArrayList();
                tempList.add(vo);
                userSignSerialMap.put(transDate, tempList);
             }
             else {
                /*某个vo之前已经存放过了,则直接追加数据到原来的List里**/
                tempList.add(vo);
             }
          }
       }
       return userSignSerialMap;
    }

转载于:https://www.cnblogs.com/move22/p/10429060.html

[https_blog.csdn.net_weixin_30416497_article_details_97049185]: https://blog.csdn.net/weixin_30416497/article/details/97049185
[https_blog.csdn.net_gsls200808_article_details_86501905]: https://blog.csdn.net/gsls200808/article/details/86501905
[https_blog.csdn.net_qq_43563538_article_details_97912937]: https://blog.csdn.net/qq_43563538/article/details/97912937
[https_blog.csdn.net_CMEguagua_article_details_94552978]: https://blog.csdn.net/CMEguagua/article/details/94552978
[https_blog.csdn.net_Man20161217_article_details_82657698]: https://blog.csdn.net/Man20161217/article/details/82657698
[http_www.cnblogs.com_move22_p_10429060.html]: http://www.cnblogs.com/move22/p/10429060.html