Check if null attribute present in Optional and return String Java Stream API

user12051965 :

I have the following

class Person
  private String firstName;
  private String familyName;

  // Setters and Getters

And I have the following method

public String getFullName(Optional<Person> persons) {
  return persons
           .map(person -> (person.getFirstName() + " " + person.getFamilyName())).orElse("Invalid");
}

I just want to check if either first or last name is null, display "Invalid" for that person. I was thinking to add a method for validation but I am sure there is an easier way I cannot think about.

YCF_L :

You are looking to Optional::filter, before the map:

return persons
        .filter(person -> person.getFamilyName() != null && person.getFirstName() != null)
        .map(person -> person.getFirstName() + " " + person.getFamilyName())
        .orElse("Invalid");

Which mean, if the family and first names are not null then create your concatination, otherwise return an Invalid message, or you can even throw an exception by using orElseThrow

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