I have a (Scala) object hierarchy like so:
class Vehicle {
...
}
class Car extends Vehicle {
...
}
class Motorcycle extends Vehicle {
...
}
etc. I have a method that takes some input and returns the class type of the Vehicle
subclass that is "best suited for it":
def chooseVehicleType(fizz : String) : Class[_ <: VehicleType] = {
fizz match {
case "buzz" => classOf[Car]
case "foo" => classOf[Motorcycle]
// etc.
case _ => throw new UnsupportedOperationException(s"We don't support ${fizz} yet.")
}
}
The problem here is that I get compiler errors on the classOf
assignments:
type mismatch; found : Classcom.me.myapp.model.Car required: Class[com.me.myapp.model.Vehicle] Note: com.me.myapp.model.Car <: com.me.myapp.model.Vehicle, but Java-defined class Class is invariant in type T. You may wish to investigate a wildcard type such as _ <: com.me.myapp.model.Vehicle. (SLS 3.2.10)
Any ideas as to what is going on here, and what the fix is?
Aucun commentaire:
Enregistrer un commentaire