I created some case classes used as messages in akka. When the program receives some messages, it calls the method asInstanceOf[], but I don't know what to put inside the brackets, as the message can be one of the 3 differents case classes.

here is a try :

abstract class Retour
case class Naissance(val sender : ActorRef) extends Retour
case class NaissanceEtMort(val sender : ActorRef) extends Retour
case class PlusUnMoisOK(val sender : ActorRef) extends Retour

but at the execution of my program I get this error message:

lapins.Clapier$PlusUnMoisOK$ cannot be cast to lapins.Clapier$Retour

can you help me?

EDIT:

the line of the error is those with [Retour] in :

val future = ask(couple,PlusUnMois)
val result = Await.result(future,timeout.duration).asInstanceOf[Retour]

and the error is below:

[ERROR] [07/02/2015 01:33:48.436] [clapier-akka.actor.default-dispatcher-5] [akka://clapier/user/$a] lapins.Clapier$PlusUnMoisOK$ cannot be cast to lapins.Clapier$Retour
akka.actor.ActorInitializationException: exception during creation

EDIT2:

resolved! the message sending was incorrectly written : indeed, I wrote "sender ! PlusUnMoisOK" instead of "sender ! PlusUnMoisOK(self)"

With:

ask(couple,PlusUnMois)

You are sending the class PlusUnMois as a message. If you are doing the same in your couple actor Await.result is returning the class PlusUnMois not an object of PlusUnMois. Trying to cast the class PlusUnMois to Retour results to an error. Try sending an instance of PlusUnMois, like:

val future = ask(couple,new PlusUnMois(someActorRef))

The same should be done in your couple actor:

sender ! new PlusUnMois(someOtherActorRef)

Moreover, instead of using asInstanceOf consider using pattern matching:

 Await.result(future,timeout.duration) match {
   case m : Naissance => // do something Naissance
   case m : NaissanceEtMort => // do something NaissanceEtMort
   case m : PlusUnMoisOK => // do something PlusUnMoisOK
 }