How do I concisely write a || b where a and b are Optional values?

Optional<Integer> aOrB =  a.isPresent() ? a : b;

In java-9 you can follow any of these :

✓ Simply chain it using the or as :-

Optional<Integer> a, b, c, d; // initialized
Optional<Integer> opOr = a.or(() -> b).or(() -> c).or(() -> d);

implementation documented as -

If a value is present, returns an Optional describing the value, otherwise returns an Optional produced by the supplying function.

✓ Alternatively as pointed out by @Holger, use the stream as:-

Optional<Integer> opOr = Stream.of(a, b, c, d).flatMap(Optional::stream).findFirst();

implementation documented as -

If a value is present, returns a sequential Stream containing only that value, otherwise returns an empty Stream.

In java-8 we don't have any solution to easy chain Optional objects, but you can try with:

Stream.of(a, b)
    .filter(op -> op.isPresent())
    .map(op -> op.get())
    .findFirst();

In java9 you can do:

Optional<Integer> result = a.or(() -> b);

Related