This article aims to show how to use Kotlin Coroutines and remove Reaxtive eXtensions (Rx).

Benefits

To start let's consider four benefits of Coroutines over Rx:

Suspending over Blocking

To run non-blocking code using Rx you'd write something like this:

Observable.interval(1, TimeUnit.SECONDS)
    .subscribe {
        textView.text = "$it seconds have passed"
    }

Which is effectively creating a new thread. Threads are heavy objects in terms of memory and performance.

Both are critical in the mobile development world.

You can achieve the same behavior using the following snippet:

launch {
    var i = 0
    while (true){
        textView.text = "${it++} seconds have passed"
        delay(1000)
    }
}

Essentially, Coroutines are light-weight threads but we don't create any real thread.
Here we are using non-blocking delay() function, which is a special suspending function that does not block a thread but suspends the Coroutine.