Kotlin Programming Cookbook

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Whenever in doubt, whether using thread or coroutines, remember these lines by Roman (an engineer from the JetBrains team):

"Coroutines are for asynchronous tasks that wait for something most of the time. Threads are for CPU-intensive tasks."

In Android's context, you always want to update the UI, but you can't do it from background thread. Coroutines have a solution for this. Let's take a look at the next example:

launch(UI) {     val sum = lengthyJobOne.await() +lengthyJobTwo.await()     myTextView.text = "Sum of results is $sum."}

In the preceding code, not only can we compute two jobs in the background without blocking the main thread, we can also touch the UI thread for updating views.