In this section, we will study various ways of creating
Observable objects. We will learn how to subscribe to different kinds of events produced by
Observable instances and learn how to correctly create custom
Observable objects. Finally, we will discuss the difference between cold and hot observables.
Observable object is an object that has a method called
subscribe, which takes an object called an observer as a parameter. The observer is a user-specified object with custom event-handling logic. When we call the
subscribe method with a specific observer, we can say that the observer becomes subscribed to the respective
Observable object. Every time the
Observable object produces an event, its subscribed observers get notified.
The Rx implementation for Scala is not a part of the Scala standard library. To use Rx in Scala, we need to add the following dependency to our
libraryDependencies += "com.netflix.rxjava" % "rxjava-scala" % "0.19.1"