lambda表达式生成map

Map apEstateIdToEstateVrMap =

    estateVrs.stream().collect(Collectors.toMap(arg -> arg.getApEstateId(), arg -> arg, (o, n) -> n ));



Map apEstateIdToEstatesVrMap = estateVrs.stream()

    .collect(Collectors.groupingBy(EstateVr::getApEstateId));