工作中常用的lambda 操作
Lambda表达式将 List<String> 转 List<Long>
List<String> collect = new ArrayList<>();
collect.add("123");
collect.add("456");
List<Long> userIdList = collect.stream().map(item -> Long.parseLong(item)).collect(Collectors.toList());
lambda表达式将List对象某个字段转换以逗号分隔的String类型
String invoiceNos = receiptDTOList.stream() .map(ErpPurchaseInvoiceReceiptDTO::getInvoiceNo).collect(Collectors.joining(","));
表达式将List对象某个字段转换新List List<ErpPurchaseInvoiceReceiptDTO> receiptDTOList= unionDtos.stream() .map(ErpPurchaseInvoiceUnionDTO::getPurchaseInvoiceReceipt).collect(Collectors.toList());