How to handle NPE in the intermediate operations of Optional/Stream?

Question

public class Person {
  private String name;
  private Address address;
}
public class Address {
  private City city
}
public class City {
  private String name;
}


Optional.of(Person::getAddress).map(Address::getCity).map(City::getName).orElseThrow();

The middle two .map may throw NPE because getAddress and getCity may return null. What's the best approach to handle NPE here?

Answer 1

Person person = new Person();
Optional.ofNullable(person.getAddress())
        .flatMap(p -> Optional.of(p.getCity()))
        .flatMap(c -> Optional.of(c.getName()))
        .orElseThrow(NullPointerException::new);