Coroutine scope on Application class android

Question

I need a reference to coroutine scope on my android Application. i did the following

class TodoApplication : Application() {
    private var job = Job()
    private val applicationScope = CoroutineScope(Dispatchers.Main + job)

    val tasksRepository: TasksRepository
        get() = ServiceLocator.provideTasksRepository(this, applicationScope)

}

Is this the way to do it. If so how can I cancel coroutines launched on this scope job.cancel()

Application class don't have onDestroy method as Activities

Answer 1

NO , GlobalScope will NOT be suitable for Application instance.

As mention here in this article here:

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There are multiple reasons why you shouldn’t use GlobalScope:

• Promotes hard-coding values. It might be tempting to hardcode Dispatchers if you use GlobalScope straight-away. That’s a bad practice!

• It makes testing very hard. As your code is going to be executed in an uncontrolled scope, you won’t be able to manage execution of work started by it.

• You can’t have a common CoroutineContext for all coroutines built into the scope as we did with the applicationScope. Instead, you’d have to pass a common CoroutineContext to all coroutines started by GlobalScope.

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So, one solution for this is to create your own scope like this: val applicationScope = CoroutineScope(SupervisorJob() + Dispatchers.Main) But better yet, as pointed out by @Raman in the comments, use the equivalent that's already available to you:

kotlinx.coroutines.MainScope()

We don’t need to cancel this scope since we want it to remain active as long as the application process is alive, so we don’t hold a reference to the SupervisorJob. We can use this scope to run coroutines that need a longer lifetime than the calling scope might offer in our app.

Answer 2

GlobalScope will be suitable for Application instance.The get() method of taskRepository variable will work as Provider Pattern. It shouldn't be in app instance. It can be replace with lazy method.