Why not just rewrite it like ``` val first Deferred lt Unit gt = async firstTask let doFirstStuff val second Deferred lt Unit gt = async secondTask let doSecondStuff first await second await ```

val first:  Deferred<Unit> = async { 
   firstTask().let { doFirstStuff() }
}
val second: Deferred<Unit> = async {    
    secondTask().let { doSecondStuff() }
}
first.await()
second.await()

Bjarne Gelotte

04/13/2018, 9:24 AM

Ah I see.

doFirstStuff

and

doSecondStuff

needs to be done on the UI thread in my case. In this example they will be called on another thread, right?

gildor

04/13/2018, 9:31 AM

You can run them on any thread

just use

withContext(UI) { doFirstStuff() }

also if you do this for UI don’t forget to manage UI lifecycle (probably you want to cancel those tasks in case of UI destroy)

But you right, async by default runs all the task on CommonPool dispatcher

Bjarne Gelotte

04/13/2018, 9:33 AM

Ah thanks 🙂 I think maybe in my case another

launch

will be useful. But I wasn't sure if nestled

launches

is good/idiomatic

gildor

04/13/2018, 9:34 AM

nested launch? I don’t see why do you need nested launch

I mean:

launch {
    val result = firstTask()
    withContext(UI) { result.doFirstStuff() }
}
launch {
    val result = secondTask()
    withContext(UI) { result.doSecondStuff() }
}

Or in opposite way, you can use UI context for launch and wrap secondTask (it’s not always necessary, depends on what firstTask/secondTask does)

Bjarne Gelotte

04/13/2018, 9:38 AM

In my case I'm already inside a launch. But I should probably go back and refactor when I start the first launch

gildor

04/13/2018, 9:39 AM

Oh, I see, yes, of course choice between async/launch/withContext always based on your case and what is more convenient and correct for your semantics

nothing wrong with nested launch if it works for you. It’s just one coroutine just starts some child coroutines

Bjarne Gelotte

04/13/2018, 9:40 AM

Ok! I think this last example will work nicely in my case if I restructure the code a bit. Thanks a lot!

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