1.分組

  private List<SaleGroupByStoreBO> groupByStoreBOList(BusinessSalesRequest request) {
        List<BusinessSalesVO> saleTypeAndStoreList = businessSalesMapper.getSaleTypeAndStore(request);
        if (CollectionUtils.isEmpty(saleTypeAndStoreList)) {
            return null;
        }
        List
 
<SaleGroupByStoreBO> saleGroupByTypeBOList = new ArrayList<>();
        Map<String, List<BusinessSalesVO>> collect = saleTypeAndStoreList.stream().collect(groupingBy(BusinessSalesVO::getStoreId));
        for (Map.Entry<String, List<BusinessSalesVO>> listEntry : collect.entrySet()) {
            SaleGroupByStoreBO saleGroupByTypeBO 
 
= new SaleGroupByStoreBO();
            saleGroupByTypeBO.setStoreId(listEntry.getKey());
            saleGroupByTypeBO.setSaleVOList(listEntry.getValue());
            saleGroupByTypeBOList.add(saleGroupByTypeBO);
        }
        return saleGroupByTypeBOList;
    }

2.排序（降序）

 List<SaleDetailTypeAndStoreBO> collect =
                boList.stream().sorted(Comparator.comparing(SaleDetailTypeAndStoreBO::getCollectStoreSale).reversed()).collect(Collectors.toList());
 

3.判斷集合中是否存在某個值

for (String storeId : storeList) {
    Optional<BusinessSalesAllStoreBO> any = allStoreSales.stream().filter(a -> a.getStoreId().equals(storeId)).findAny();
    if (!any.isPresent()) {
        stringList.add(getBusinessStoreName(storeId));
        //想要獲取值時
        //String storeName=any.get().getStoreName();
    }
}

4.端口占用