object actors is not a member of package scala

Question

I want to use thread pool in my scala project. It can runs well in my IntelliJ Idea, but it throws exception when I compile the project use maven command line: mvn compile. I have added the dependencies "scala-libray" and "scala-actors", but nothing ever effects. Can you help me?

My code:

import scala.actors.threadpool.Executors

val execService = Executors.newFixedThreadPool(10)

The error:

[ERROR] /project../server/EasyServer.scala:6: error: object actors is not a member of package scala
[ERROR] import scala.actors.threadpool.Executors
[ERROR]              ^
[ERROR] /project../server/EasyServer.scala:16: error: not found: value Executors
[ERROR]         val execService = Executors.newFixedThreadPool(10)
[ERROR]                           ^
[ERROR] two errors found

A part of my pom.xml:

<properties>
    <scala.version>2.11.6</scala.version>
</properties>

<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>${scala.version}</version>
        </dependency>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-actors</artifactId>
            <version>${scala.version}</version>
        </dependency>
    </dependencies>
</dependencyManagement>

<build>
    <sourceDirectory>src/main/scala</sourceDirectory>
    <testSourceDirectory>src/test/java</testSourceDirectory>
    <resources>
        <resource>
            <directory>${basedir}/src/main/resources</directory>
            <includes>
                <include>**/*</include>
            </includes>
            <excludes>
                <exclude>**/.svn/</exclude>
            </excludes>
        </resource>
    </resources>

    <plugins>

        <!-- the Maven compiler plugin will compile Java source files -->
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <version>2.5.1</version>
            <configuration>
                <source>1.7</source>
                <target>1.7</target>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-resources-plugin</artifactId>
            <version>2.6</version>
            <configuration>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>

        <!-- the Maven Scala plugin will compile Scala source files -->
        <plugin>
            <groupId>net.alchim31.maven</groupId>
            <artifactId>scala-maven-plugin</artifactId>
            <version>3.2.0</version>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>testCompile</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

        <!--
            Bind the maven-assembly-plugin to the package phase this will create
            a jar file without the storm dependencies suitable for deployment to
            a cluster.
        -->
        <plugin>
            <artifactId>maven-assembly-plugin</artifactId>
            <configuration>
                <descriptorRefs>
                    <descriptorRef>jar-with-dependencies</descriptorRef>
                </descriptorRefs>
            </configuration>
            <executions>
                <execution>
                    <id>make-assembly</id>
                    <phase>package</phase>
                    <goals>
                        <goal>single</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>

    </plugins>
</build>

Answer 1

Starting from 2.11, scala actors are shipped as a separate library :

<dependency>
  <groupId>org.scala-lang</groupId>
  <artifactId>scala-actors</artifactId>
  <version>2.11.6</version>
</dependency>

Note that they are also deprecated in favor of Akka : http://docs.scala-lang.org/overviews/core/actors-migration-guide.html