用Hibernate中的最后一次迭代覆盖的值

Question

我有这些实体： 汽车/车辆/汽车/ CustomDTO

Car
- long carId
Vehicle
- long vehicleId;
Auto
- long autoTypeId;
CustomDTO
- long autoTypeId;
- String autoTypeName;
- List<Car> cars;

public List<Car> getCarByVehicleAndType(long vehicleId, long autoTypeId){
    List<Car> cars = new ArrayList<Car>();
    List<Car> carsInCarVehicleType = carService.getCarsInCarVehicleType(vehicleId, autoTypeId); //DAO Fetch cars IN Cat-Vehicle-Type table
    for(Car car : carsInCarVehicleType){
        car.selected(true);
    }
    List<Car> carsNotInCarVehicleType = carService.getCarsNotInCarVehicleType(vehicleId, autoTypeId); //DAO Fetch cars NOT IN Cat-Vehicle-Type table
    for(Car car : carsNotInCarVehicleType){
        car.selected(false);
    }

    cars.addAll(carsInCarVehicleType);
    cars.addAll(carsNotInCarVehicleType);

    return cars;
}

public List<CustomDTO> constructVehicleDTO(long vehicleId){
    List<Auto> autos = autoService.getAutos(); //DAO Fetch all autos
    List<CustomDTO> dtoList = new ArrayList<CustomDTO>();
    for(Auto auto : autos){
        CustomDTO dto = new CustomDTO();
        dto.setAutoTypeId(auto.getAutoTypeId());
        dto.setAutoTypeName(auto.getAutoTypeName());
        dto.setCars(getCarByVehicleAndType(vehicleId, auto.getAutoTypeId());
        dtoList.add(dto);
    }
    return dtoList;
}

在上面的方法中 - 当返回dtoList时， dto.setCars(...)会被最后一次迭代值覆盖。因此，对于每辆车，我都会获得相同的车辆清单。这不会发生在普通的Java操作中。我怀疑我在这里混淆了Hibernate对象的生命周期。

如果我不清楚，请告诉我。