Lombok builder - ignore objects with null value

Question

My first steps with Lombok @Builder.

So I receive ExternalVehicles object from external service (10 cars inside).

public class CarConverter {

    private Car convertToCar(ExternalVehicles vehicles) {

        return Car.builder()
                .plateNumber(getPlateNumberFromObjectNestedInExternalVehicles("plateNumber"))
                .brand(getBrandFromObjectNestedInExternalVehicles("brand"))
                .build();
    }
}

For one car, the null is received in plateNumber field. So I would like to ignore this car and convert only 9.

How can I do this?

can this help you : https://stackoverflow.com/questions/59774417/how-can-i-exclude-a-property-from-a-lombok-builder-only-if-the-property-is-null — Aymen Ben Salah, Jun 10 '22 at 10:49
Sounds like something that should be done by filtering objects in `ExternalVehicles`, not by a builder. — Chaosfire, Jun 10 '22 at 10:51

score 0 · Accepted Answer · answered Jun 17 '22 at 04:34

There are multiple things to mention:

you can filter the cars before the convertion

externalCars.stream()
     .filter(car -> Objects.nonNull() && isCarValid())
     .map(CarConverter::convertToCar)
     .collect(Collectors.toSet())

you can do some checks within your conversion method and filter afterwards

public class CarConverter {

    private Car convertToCar(ExternalVehicles vehicles) {
        if (vehicles == null || getPlateNumberFromObjectNestedInExternalVehicles("plateNumber") == null)
            return null

        return Car.builder()
                .plateNumber(getPlateNumberFromObjectNestedInExternalVehicles("plateNumber"))
                .brand(getBrandFromObjectNestedInExternalVehicles("brand"))
                .build();
    }
}

and then filter before the collection

externalCars.stream()
     .map(CarConverter::convertToCar)
     .filter(car -> Objects.nonNull())
     .collect(Collectors.toSet())

In my experience, this leads to less NullPointerExceptions

Just for completion, there are also way,to fail the .build() method as seen here: https://stackoverflow.com/a/72654258/1538176

Lombok builder - ignore objects with null value

1 Answers1