Converting Vertx Future<T> To RX Observable<Optional<T>>

Question

I need to provide some util function that converts a Vertx Future<T> to Rx Observable<Optional<T>> for backwards compatibility.

Should this be good enough?

Observable.fromCompletionStage(future.toCompletionStage());

Thanks

Answer 1

No, because Observable.fromCompletionStage returns Observable<T>, not Observable<Optional<T>>.

You must create the Optional from the future result with ofNullable:

Observable.fromCompletionStage(future.map(Optional::ofNullable).toCompletionStage());