16 Working with Mono and audience Q&A (Reactive programming with Java - full course)

Course: Reactive programming in Java
Covers: Reactive fundamentals, Project Reactor
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Learn the basics of reactive programming. You will learn to "THINK REACTIVE" - understand the paradigm shift and thinking change necessary to write code in a reactive way using Project Reactor.
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[@JimmyHeller]

I'm a seasoned Java developer and I watched this full course. You are a hell of a teacher! Thank you!

[@aplusphilic]

You have effective way of digesting complex topics in a way it’s easier to understand o matter someones experience. Great series. BTW your IDE looks really clean, do you mind sharing theme and font that you are using?

[@mostinho7]

Done thanks Mono has block() or blockOptional methods which return the value emitted by mono by blocking until it’s available Blocking loses the benefits of reactive programming, you shouldn’t block

[@deepaksamria1862]

Just love this series... thanks sir 👏 for valuable content

[@varunvijaywargi5497]

In this section, do we need the System.out.println statement at the along with System.in.read() since we are blocking and Mono is expected to return only 1 value?

[@anands53]

@Java Brains, thank you so much for your informative courses. I got a doubt using the block() in mono. Can we use Mono num = ReactiveSources.intNumberMono(); sysout(num); //getting output as 'MonoDelayElement' Why am I not getting the number 42. this is also a blocking code right? I mean until the variable num is assigned, we cannot go to next line. Please help me understand.

[@sanguk2066]

If we care building User object from the response of two service calls then how can i return Mono back from the controller ?

[@PriyankaSharma-vw2gx]

@Java.Brains At 3:28 mins, we are blocking until mono emits an Integer. Mono by deifinition emits 0 or 1 element. What if it doesn't emit anything. Is the blocking indefinite? Or does mono give a signal in some way that it has nothing to emit?

[@Musicforlifeformusic]

Can you please please make a video on micronaut http client. I am having a very hard time implementing a non blocking http request.

[@BekTesfa]

Can we say that a Mono is a special case of Flux ? (or Mono is a Flux where N is 1) ?

[@SS-ej7zq]

Can you please make a video for Spring boot crud operation in vs code with step by step process

[@hyperborean72]

I still did not get it - in what way Flux/Mono is preferable over CompletableFuture

[@updownftw]

If my controller is returning a Mono and I’m calling the controller end point from let’s say Angular, how will angular handle it ? Will the code be same in angular as for a normal request call ?

[@DeathBender]

im assuming you are calling via HTTP ? Angular uses Observables and your HTTP calls in Angular will return an Observable, which work similar. You either pass to your subscribe() method then an observer (which is encouraged by Angular) or the onNext, onError and onComplete methods directly (works as of now but is deprecated rather use the Observer that holds these methods).

[@updownftw]

@@DeathBender so basically subscribe method of Angular works similar to subscribe method of Project Reactor

[@DeathBender]

@@updownftw well there are differences ofc it's ReactiveX or RxJS (might help if you are familiar with RxJava) but even some operators are the same or very similar, so basically yes, i'd still encourage you to look up about it, Observables are still a different "beast" ;)

[@updownftw]

@@DeathBender Thanks bro, Koushik should make a full stack Angular/React and Project Reactor tutorial. It would be interesting.

[@DeathBender]

@@updownftw well he should have some Angular + SpringBoot "stuff" (pretty sure i've seen smth) beyond that you can just use some Reactive Controller (which are not that different) with Webflux and make HTTP calls from a very basic Angular app

[@BekTesfa]

Imagine that you are calling a service that emits a Mono, and you want to flatten that Mono into a java object and access its property then I think we should use block() on the emitted Mono. Is this a good practice? Does it affect the performance since we are blocking it ? Is there an alternative solution ?

[@1994rohithp]

if you are using block on the Mono to get the object, you are actually beating the purpose. It's not reactive anymore. Ideally, you get a Mono from the Command layer to the Service layer to the Controller layer. The controller also returns Mono.