Updating persons in database with newly created addresses [closed]

Question

I have the following code, and I'd like to refactor it to a more functional way:

public void processPersons(List<Person> personList) {
    for (Person person : personList) {
        Integer addressId = createAddress(person);
        if (addressId != null) {
            updateDbStatus(addressId, person);
        }
    }
}

How do I convert the above to a more functional style of programming?

Answer 1

One of variants is to have PersonWithAddress subclass with created addressIp:

    persons
            .stream()
            .map(PersonWithAddress::new)
            .forEach(this::updateDbStatus);

You call updateDbStatus where check the address for null:

void updateDbStatus(PersonWithAddress personWithAddress) {
    if (personWithAddress.getAddressIp() != null) {
        // do the update
    }
}

Model classes like these ones:

class Person{
    Person(final Person original) {
        // copy constructor
    }
}

class PersonWithAddress extends Person {
    private final Integer addressIp;

    PersonWithAddress(final Person person) {
        super(person);
        this.addressIp = createAddress();
    }

    Integer getAddressIp() {
        return addressIp;
    }

    private Integer createAddress() {
        // have a logic to create an address
        return 0;
    }
}

Answer 2

As you are working with Java 8, you'd be happy to explore the other features in it like Optional<T>

You can change your createAddress() to return an Optional which will be more expressive.

Optional<Person> createAddress(person){
   //write your logic and return the result wrapped in an Optional
}

As addressId has one-to-one mapping with Person, you should add an identifier to the Person class to hold the addressId. Then you have to modify the method signature of updateDbStatus as updateDbStatus(Person person)

class SomeClass{

 void someMethod(){

   personList.stream()
    .map(SomeClass::createAddress)
    .ifPresent(SomeClass::updateDbStatus)
 }

}