Get value from one Optional or another

Question

I have two java.util.Optional instances and I want to get an Optional that either:

• Has the value of the first Optional, if it has a v

Answer 1

I had a few encounters with a problem that might've been solved with JDK 9 Optional::or and couldn't because we use JDK 8. Finally I added a util class with this method:

@SafeVarargs
public static  Optional firstPresent(final Supplier>... optionals) {
    return Stream.of(optionals)
            .map(Supplier::get)
            .filter(Optional::isPresent)
            .findFirst()
            .orElse(Optional.empty());
}

Now you can supply any number of optionals to this method and they'll be lazily evaluated like so:

    final Optional username = OptionalUtil.firstPresent(
            () -> findNameInUserData(user.getBasicData()),
            () -> findNameInUserAddress(user.getAddress()),
            () -> findDefaultUsername());

Now, findNameInUserAddress will only be called if findNameInUserData returns empty. findDefaultUsername will only be called if both findNameInUserData and findNameInUserAddress return empty etc.