Reactive Programming in Kotlin

The flatMap operator

Where the map operator takes each emission and transforms them, the flatMap operator creates a new producer, applying the function you passed to each emission of the source producer.

So, let's look at this example:

    fun main(args: Array<String>) { 
      val observable = listOf(10,9,8,7,6,5,4,3,2,1).toObservable() 
      observable.flatMap { 
        number-> Observable.just("Transforming Int to String $number") 
      }.subscribe { 
        item-> println("Received $item") 
      } 
   } 

Here is the output:

The output is similar to the previous one, but the logic is different. Instead of just returning the String, we are returning Observable with the desired String ...