How to convert an Optional into a Stream?

Question

I want to prepend a stream with an Optional. Since Stream.concat can only concatinate Streams I have this question:

How do I convert an Optional

Answer 1

I can recommend Guava's Streams.stream(optional) method if you are not on Java 9. A simple example:

Streams.stream(Optional.of("Hello"))

Also possible to static import Streams.stream, so you can just write

stream(Optional.of("Hello"))