How to convert an Optional to an OptionalInt?

Question

I have an Optional that I want to \"convert\" to an OptionalInt, but there doesn\'t seem to be a simple way to do this.

Here\'s what I want

Answer 1

While the code isn't more readable than an ordinary conditional expression, there is a simple solution:

public OptionalInt getInt() {
    return Stream.of(someString).filter(s -> s != null && s.matches("\\d+"))
        .mapToInt(Integer::parseInt).findAny();
}

---

With Java 9, you could use

public OptionalInt getInt() {
    return Stream.ofNullable(someString).filter(s -> s.matches("\\d+"))
        .mapToInt(Integer::parseInt).findAny();
}

As said, neither is more readable than an ordinary conditional expression, but I think, it still looks better than using mapOrElseGet (and the first variant doesn't need Java 9.