Java8 stream操作

list转map

                    Map map = list.stream().collect(Collectors.toMap(m -> m.getSkuNo(), m -> m.getOrderNum(), (k1, k2) -> k1));

list中某个属性转list

            List list = orderList.stream().map(m -> m.getSkuNo()).distinct().collect(Collectors.toList());

根据某个属性分组

        Map excelMap = list.stream().collect(Collectors.groupingBy(o -> o.getOrderId().trim()));