I wasn't sure wether to post here or in <#C0B8M7BU...

# coroutines

[james]

I wasn't sure wether to post here or in #android, but the issue I'm having is with the Kotlin coroutines library. Just need some help getting my head around what I'm doing wrong!

# MainActivity.kt

override fun onStart() {
        super.onStart()
        var applicationID = runBlocking { Application.registerDevice() }

        Log.d("AppID on-start", applicationID)
    }

# Application.kt

object Application {
    suspend fun registerDevice(): String {
        return getTokenAsync().await()
    }

    private suspend fun getTokenAsync(): kotlinx.coroutines.Deferred<String> = coroutineScope {
        async {
            return@async FirebaseInstallations.getInstance().id.result.toString()
        }
    }
}

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.application, PID: 20890
    java.lang.IllegalStateException: Task is not yet complete

If anyone could see where I'm going wrong and help point me in the right direction on what I can do to resolve this I would really appreciate it 🙂

Thanks in advance!

[Ali Albaali]

Have you tried removing the `return`s?

[james]

I still get Task is not yet completed with the returns removed

[Ali Albaali]

Firebase is already asynchronous so wrapping it with Coroutines won't help.

[james]

I’ve also tried running it in a function like this

private fun fetchID(): String {
        var token: String
        FirebaseInstallations.getInstance().id
            .addOnCompleteListener(OnCompleteListener<String?> { task ->
                if (task.isSuccessful) {
                    token = task.result.toString()
                    Log.d("App-Token", token)
                }
            })
        return token
    }

But token is not initialised and if I initialise it then it won’t use the updated value from the Firebase function

[Ali Albaali]

You're saying it will return immediately, correct?

[james]

I guess so? This is how it’s being called

fun registerDevice() {
        val token = fetchID()
        // do other stuff with token
    }

How would I go about waiting for it to return the FirebaseInstallations task?

[akatkov]

https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/suspend-cancellable-coroutine.html

[akatkov]

You can see the example in there about how you would set up a callback with your onCompletion listener

[james]

Perfect got it sorted, thank you @akatkov :)