Scala PingPong Example

pingpong.scala

import akka.actor.{Actor, ActorRef, ActorSystem, Props}

case object PingMessage
case object PongMessage
case object StartMessage
case object StopMessage

class Ping(pongRef: ActorRef) extends Actor {
  var count = 0

  def incrementAndPrint() = {count += 1; println("ping")}

  def receive = {
    case StartMessage =>
      incrementAndPrint
      pongRef ! PingMessage
    case PongMessage =>
      incrementAndPrint
      if (count > 99) {
        pongRef ! StopMessage
        println("ping stopped")
      } else {
        pongRef ! PingMessage
      }
  }
}


class Pong extends Actor {
  def receive = {
    case PingMessage =>
      println("Pong")
      sender ! PongMessage
    case StopMessage =>
      println("pong stopped")
      context.system.terminate()
  }
}

object PingPongTest extends App {
  val system = ActorSystem("PingPongSystem")
  val pong = system.actorOf(Props[Pong], name = "pong")
  val ping = system.actorOf(Props(new Ping(pong)), name = "ping")
  ping ! StartMessage
}

Reference: http://alvinalexander.com/scala/scala-akka-actors-ping-pong-simple-example