akka创建actor时报错：IllegalArgumentException: no matching constructor found on class $iwC$$iwC$$iwC$$iwC$

在spark-shell中输入范例中的代码：

import akka.actor.Actor
import akka.actor.Props
import akka.event.Logging
 
class MyActor extends Actor {
  val log = Logging(context.system, this)
  def receive = {
    case "test" ⇒ log.info("received test")
    case _      ⇒ log.info("received unknown message")
  }
}

val system = ActorSystem("MySystem")
  val myActor = system.actorOf(Props[MyActor], name = "myactor")

百思不得其解！最后终于找到了原因：不能采用内嵌类作为actor类！！！！spark-shell里面的类会被认为是内嵌类，为了避免以上错误，需要单独写类文件。

stackoverflow里面是这么解释的：

Take this example:
class A{
  class B{}
}
I can do new A, but new B will return an error. I have to do:
val a = new A
val b = new a.B
That's why akka failed to create this actor.