java8 lamda表达式

list 分组

　　1.多字段联合，分组

list.stream().collect(Collectors.groupingBy(o -> o.getSkuName() + "_" + o.getOeCode(), Collectors.toList()));

　　2.求和计算 

Integer num =list.stream().mapToInt(n -> n.getNum()).sum();

　　3.分组-排序

list.stream().collect(Collectors.groupingBy(EnquiryDetail::getQualityId))
            .values().stream().map(enquiryDetails -> {
                List<EnquiryDetail> rspDetails = enquiryDetails.stream().sorted(Comparator.comparing(EnquiryDetail::getQuotePrice)).collect(Collectors.toList());
                rspDetails.get(0).setCheck(true);
                return rspDetails;
            }).flatMap(Collection::stream).collect(Collectors.toList());

 //按价格排序

//                    List<SupplierEnquiryDetail> details = busGroup.entrySet().stream().map(detail -> {
//                        SupplierEnquiryDetail supplyEnquiryCompareResp = BeanUtil.copyProperties(detail, SupplierEnquiryDetail.class);
//                        return supplyEnquiryCompareResp;
//                    }).sorted(Comparator.comparing(SupplierEnquiryDetail::getTaxQuotePrice) ).collect(Collectors.toList());

 

 

 // return respDetails.stream().collect(Collectors.groupingBy(EnquiryCompareResp.EnquiryDetail::getQualityId))
//            .values().stream().map(enquiryDetails -> {
//                List<EnquiryCompareResp.EnquiryDetail> rspDetails = enquiryDetails.stream().sorted(Comparator.comparing(EnquiryCompareResp.EnquiryDetail::getQuotePrice)).collect(Collectors.toList());
//                rspDetails.get(0).setCheck(true);
//                return rspDetails;
//            }).flatMap(Collection::stream).collect(Collectors.toList());

 过滤

 

respDetails.stream().filter(item -> !request.getQualityId().contains(item.getQualityId())).collect(Collectors.toList());