Android Kotlin Task To Be Executed Using Coroutines

As an example, I'm using FusedLocationProviderClient to access the current location, which returns a task which callback will eventually return the location. The method looks somet

Solution 1:

The kotlinx-coroutines-play-services library has a Task<T>.await(): T helper.

import kotlinx.coroutines.tasks.await

suspendfungetLocation(): Location? = 
    LocationServices.getFusedLocationProviderClient(context).lastLocation.await()

Alternatively take a look at Blocking Tasks

It would be used the next way:

suspendfungetLocation(): Location? =
    withContext(Dispachers.IO){
        val flpc = LocationServices.getFusedLocationProviderClient(context)
        try{
            return@withContext Tasks.await(flpc.lastLocation)
        catch(ex: Exception){
            ex.printStackTrace()
        }
        return@withContextnull
    }

Just to add to this example, for completion purposes, the call to getLocation() would be done the next way:

coroutineScope.launch(Dispatchers.Main) {
    val location = LocationReceiver.getLocation(context)
    ...
}

However this negates the benefits of coroutines by not leveraging the available callback and blocking a thread on the IO dispatcher and should not be used if the alternative is available.

Solution 2:

Another way that I have don this that can also be used with any callback type interface is to use suspendCoroutine<T> {}.

So for this example it would be:

suspendfungetLocation(): Location? {
    return suspendCoroutine<Location?> { continuation ->
        val flpc = LocationServices.getFusedLocationProviderClient(it)
        flpc.lastLocation.addOnSuccessListener { location ->
            continuation.resume(location)
        }
        // you should add error listener and call 'continuation.resume(null)'// or 'continuation.resumeWith(Result.failure(exception))'
    }
}