java - 错误 - ReceiveBuilder 中的构建方法编译错误，无法解析类型 scala.Product

Question

我是 Akka-Actor 的新手。

尝试运行简单的 akka-actor 程序来理解 akka-actor。

我无法解决两个编译错误。

The method build() from the type AbstractPFBuilder<Object,BoxedUnit> refers to the missing type PartialFunction

和

The type scala.Product cannot be resolved. It is indirectly referenced from required .class files. 

Compilation error at Props props() method.

下面是实际代码。

AkkaActor 程序:

package com.abcplusd.akka;

import akka.actor.AbstractLoggingActor;
import akka.actor.ActorRef;
import akka.actor.ActorSystem;
import akka.actor.Props;
import akka.japi.pf.ReceiveBuilder;

    public class AkkaStarted {

      static class Counter extends AbstractLoggingActor {
        static class Message {}
        private int count = 0;

        {
          receive(ReceiveBuilder
              .match(Message.class, this::onMessage)
              .build()
              );
        }

        private void onMessage(Message message) {
          count ++;
          System.out.println("Increased Counter: " + count);
        }
        public static Props props() {
          return Props.create(Counter.class);
        }

       }
      public static void main (String[] args) {
        ActorSystem system = ActorSystem.create("Sample1");
        final ActorRef counter =  system.actorOf(Counter.props(), "Counter");
        counter.tell(new Counter.Message(), ActorRef.noSender());
        System.out.println("Enter to Terminate");
      }

    }

AkkaActor 版本 2.4.9。

位于我的 pom.xml 设置下方。

<properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <akka.version>2.4.9</akka.version>
  </properties>
  <dependencies>
    <dependency>
      <groupId>com.typesafe.akka</groupId>
      <artifactId>akka-actor_2.11</artifactId>
      <version>${akka.version}</version>
    </dependency>
    <dependency>
      <groupId>org.scala-lang</groupId>
      <artifactId>scala-library</artifactId>
      <version>2.12.4</version>
    </dependency>
  </dependencies>

Answer 1

通过更改 scala-lang 版本解决了编译问题。

<dependency>
   <groupId>org.scala-lang</groupId>
   <artifactId>scala-library</artifactId>
   <version>2.11.8</version>
</dependency>