So, we have Observable (the thing that should be observed upon) and we have the Observer type (that should be observed), now what? How do we connect them? Observable and Observer are like an input device (be it keyboard or mouse) and the computer; we need something to connect them (even wireless input devices have some connectivity channels, be it Bluetooth or Wi-Fi).
The subscribe operator serves the purpose of the media by connecting an Observable interface to Observer. We can pass one to three methods (onNext, onComplete, and onError) to the subscribe operator, or we can pass an instance of the Observer interface to the subscribe operator to get the Observable interface connected with Observer.
So, let's look at an example now:
fun main(args: Array<String>) {
val observable = Observable.range(1,5)//1
observable.subscribe({//2
//onNext method
println("Next-> $it")
},{
//onError Method
println("Error=>...