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

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

AND

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.

低于我的 pom.xml 设置。

<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>

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

Error - build method compilation Error at ReceiveBuilder, type scala.Product cannot be resolved

java

akka

akka-actor