Noob question. I'm using Android Studio (android d...

# getting-started

[Daniele Segato]

Noob question. I'm using Android Studio (android development)

I've Included dependencies:

implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.2"

But I cannot use async and launch in a suspend fun

suspend fun foo() {
  async {} // Unresolved reference
  launch {} // Unresolved reference
}

What am I missing here?!

EDIT: nevermind, I was remembering it wronly, I need something like coroutineScope {} or withContext(...) or something like that

[Daniele Segato]

Anyone?

[Milan Hruban]

async and launch are extension functions on CoroutineScope - you cannot call them without it

[Daniele Segato]

I'm inside a suspend fun

[wbertan]

Are you in the same module which that is imported?

[Daniele Segato]

yes, it's an android app

[wbertan]

I haven’t use that dependency, we use here:

"org.jetbrains.kotlinx:kotlinx-coroutines-core:${Versions.coroutines}"

[Daniele Segato]

implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
    implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:1.4.2")
    implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:1.4.2"
    testImplementation "org.jetbrains.kotlinx:kotlinx-coroutines-test:1.4.2"

buildscript {
    ext.kotlin_version = '1.4.21'
    repositories {
        google()
        jcenter()

    }
    dependencies {
        classpath 'com.android.tools.build:gradle:7.0.0-alpha03'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath 
    }
}

[Daniele Segato]

org.jetbrains.kotlinx:kotlinx-coroutines-android should include org.jetbrains.kotlinx:kotlinx-coroutines-core but I manually included core just in case, no difference

[Milan Hruban]

Why does it matter that you are inside suspend function?

[Daniele Segato]

cause the scope is that coroutine? it is supposed to create a child coroutine

[Daniele Segato]

otherwise structured concurrency goes out of the window

[Daniele Segato]

When I used coroutine 1.3.8 I could use async and launch just fine within a suspend fun

[Milan Hruban]

oh is it some android thing then?

[Daniele Segato]

why would it be? this is Kotlin, as far as I know there's no "android" kotlin, there's just kotlin

[Milan Hruban]

Can you please point me to some resource showing this? I am a bit lost

[Daniele Segato]

I've no idea what you are asking about @Milan Hruban

[Daniele Segato]

I do not see any change in regard to that here:
https://github.com/Kotlin/kotlinx.coroutines/blob/master/CHANGES.md

[Milan Hruban]

@Daniele Segato some code sample ideally in kotlin docs, that shows usage of async or launch in suspend function, without coroutine scope

[Daniele Segato]

https://youtu.be/Mj5P47F6nJg?t=2208▾

[Daniele Segato]

is this good enough?

[Daniele Segato]

are you saying I should do

coroutineScope {
            launch() {}
            async() {}
        }

?

[Daniele Segato]

or withContext ?

[Daniele Segato]

maybe I'm wrong but I remember using it directly inside the suspend fun you are saying this was never possible?

[Vampire]

I also think it never was possible.
Also here: https://kotlinlang.org/docs/composing-suspending-functions.html#structured-concurrency-with-async

[Daniele Segato]

I checked coroutines a while ago, studied it than had to do something else and now i'm getting back to it. I still didn't build hours of work on it

[Milan Hruban]

well it depends what you want to do - the docs will probably explain it better then me

[Daniele Segato]

I see, I was probably remembering wrongly... I always used some kind of container for that.... so now I've another question about testing, doing it in another thread.

[elizarov]

It was possible more that 2 years ago, before 1.0 release -> https://elizarov.medium.com/structured-concurrency-722d765aa952 (it also explains why it is not allowed now)

[Daniele Segato]

@elizarov ye, sorry, I actually rewatched that part and realized it...

My bad, unfurtunately I spent time to study coroutines and try them out a couple of months ago, than I suspended cause I needed SharedFlow and needed to finish a project.

Now I'm taking it up again more seriously and I just miss-remembered that.

Thanks for your answer!