Hot questions for Using RxJava 2 in spring webflux

Top Java Programmings / RxJava 2 / spring webflux


I am new to RxJava and Spring webflux. Is there a way to convert RxJava Single to Mono?

I want to return a Mono<String> from the following function.

private Single<String> toNotification(PU update, Tx<PP> tx) {
    return findChannels(update.partyId(), update.notificationId(), tx)
        .flatMap(f -> Single.just("test"));

findChannels returns flowable


You can use reactor.adapter.rxjava.RxJava2Adapter.singleToMono(io.reactivex.Single<T> source) which returns Mono<T>.

Source: RxJava2Adapter


I have been trying to learn Project Reactor 3.0 with this small application. I am struggling to compose a function for combining variables to a Movie object. In Reactor it seems like the return type is a Flux<Tuple5<>>. In RxJava2 it returns a Function5<>.


Single<Movie> movie =, getCategory(id), getName(id), getRating(id),
            (Function5<Integer, String, String, String, Double, Object>) (desc, cat, name, rating) ->
                    new Movie(id.blockingGet(), name, desc, cat, rating)).cast(Movie.class);


 Flux<Tuple5<Integer, String, String, String, Double>> tuple =
  , getDesc(id), getCategory(id), getName(id), getRating(id));

Instead of returning a Flux<Tuple5<>> I want to return a Tuple5<> or something else to create the movie just like RxJava. I do not want to subscribe to the Tuple since I am trying to return this in Spring Web Reactive. I temporarily solved it by subscribing, but I was wondering if it is possible to do the same as RxJava.

The example in this video on timestamp 1:07:54, shows it was possible in an old version.

Any solutions or suggestions are welcome!


The RxJava solution doesn't return the Movie directly, but a Single<Movie>. Reactor has a simplified zip that returns a Tuple, but that RxJava signature is comparable to Flux<Tuple5>.

So what you want is a Flux<Movie>. zip has an overload that takes a Function<Object[], V> as the first parameter: that lets you specify into which object V the values from the zipped sources are to be combined. The function will be applied with an array of these values as input, and must return the value to be emitted in the resulting Flux<V>, in your case a Movie.