InjectComponentFactory.kt

@RequiresApi(Build.VERSION_CODES.P)
// We still need default constructor for AppComponentFactory
class InjectComponentFactory : AppComponentFactory() {

    private lateinit var application: SampleApplication

    private val activityProviders: Map<String, Provider<Activity>> by lazy {
        application.appComponent.activityProviders
            .mapKeys { (key, _) -> key.name }
    }

    override fun instantiateApplication(
        cl: ClassLoader, className: String
    ): Application {
        val instantiateApplication = super.instantiateApplication(cl, className)
        // Save reference to the Application instance
        this.application = instantiateApplication as SampleApplication
        return instantiateApplication
    }

    override fun instantiateActivity(
        cl: ClassLoader, className: String, intent: Intent?
    ): Activity {
        return activityProviders[className]?.get() 
                    ?: super.instantiateActivity(cl, className, intent)
    }
}