idea运行akka第一个例子出错

import akka.actor.Actor
import akka.actor.ActorSystem
import akka.actor.Props
class HelloActor extends Actor {
  def receive = {
    case "hello" => println("您好！")
    case _ => println("您是?")
  }
}
object Main extends App {
  val system = ActorSystem("HelloSystem")
  // 缺省的Actor构造函数
  val helloActor = system.actorOf(Props[HelloActor], name = "helloactor")
  helloActor ! "hello"
  helloActor ! "喂"
}

运行时出现错误提示：scala.Predef$.refArrayOps([Ljava/lang/Object;)Lscala/collection/mutable/ArrayOps

个人系统scala版本是2.12(而且在idea的project settings--libraries中增长的是com_typesafe_akka_akka_actor_2_12_0_M1_2_4_M2库)，根据网上有人写的提示做以下修改：

将scala-sdk从2.12换为2.11

File -> Project Structure -> Global libraries -> Remove SDK -> Rebuild.

最终成功了。