Hands-On Reactive Programming in Spring 5

Producing and consuming streams

At this point, we should be familiar enough with the RxJava library to create our first small application. Let's define a stream that is represented by the Observable class. At the moment, we may assume that the Observable is a sort of generator that knows how to propagate events for subscribers as soon as they subscribe:

Observable<String> observale = Observable.create(   new Observable.OnSubscribe<String>() {      @Override      public void call(Subscriber<? super String> sub) {             // (1)         sub.onNext("Hello, reactive world!");                       // (2)         sub.onCompleted();                                          // (3)      }   });

So, here we create an Observable with a callback that will be applied as soon as the Subscriber appears (1). At that moment, our Observer will produce a one string ...