My mixed Scala/Java Maven project doesn't compile -

i have mixed scala/java project doesn't compile well.

the problem arises when java code trying call scala code in same package.

of course, have standard layout:

• src/main/java
• src/main/scala
• src/test/java
• src/test/scala

i've looked @ other similar stackoverflow questions this question little outdated. other question doesn't either.

i have followed scala-maven-plugin documentation page.

<build>     <pluginmanagement>         <plugins>             <plugin>                 <groupid>net.alchim31.maven</groupid>                 <artifactid>scala-maven-plugin</artifactid>                 <version>3.1.6</version>             </plugin>             <plugin>                 <groupid>org.apache.maven.plugins</groupid>                 <artifactid>maven-compiler-plugin</artifactid>                 <version>2.0.2</version>             </plugin>         </plugins>     </pluginmanagement>     <plugins>         <plugin>             <groupid>net.alchim31.maven</groupid>             <artifactid>scala-maven-plugin</artifactid>             <executions>                 <execution>                     <id>scala-compile-first</id>                     <phase>process-resources</phase>                     <goals>                         <goal>add-source</goal>                         <goal>compile</goal>                     </goals>                 </execution>                 <execution>                     <id>scala-test-compile</id>                     <phase>process-test-resources</phase>                     <goals>                         <goal>testcompile</goal>                     </goals>                 </execution>             </executions>         </plugin>         <plugin>             <groupid>org.apache.maven.plugins</groupid>             <artifactid>maven-compiler-plugin</artifactid>             <executions>                 <execution>                     <phase>compile</phase>                     <goals>                         <goal>compile</goal>                     </goals>                 </execution>             </executions>         </plugin>     </plugins> </build> 

i have tried unsuccessfully follow blog post.

idea project scala plugin imported pom.xml can compile , run project successfully.

what right way of doing it? java code gets compiled twice? first scala plugin , java plugin?.

here working example of pom.xml :

<?xml version="1.0" encoding="utf-8"?> <project xmlns="http://maven.apache.org/pom/4.0.0"      xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"      xsi:schemalocation="http://maven.apache.org/pom/4.0.0       http://maven.apache.org/xsd/maven-4.0.0.xsd">  <modelversion>4.0.0</modelversion>  <groupid>stackoverflow</groupid> <artifactid>q24448582</artifactid> <version>1.0-snapshot</version>  <properties>     <scala.version>2.10.3</scala.version> </properties>  <dependencies>     <dependency>         <groupid>org.scala-lang</groupid>         <artifactid>scala-library</artifactid>         <version>${scala.version}</version>     </dependency>  </dependencies>  <build>     <plugins>         <plugin>             <groupid>org.scala-tools</groupid>             <artifactid>maven-scala-plugin</artifactid>             <version>2.15.2</version>             <executions>                  <execution>                     <id>compile</id>                     <goals>                         <goal>compile</goal>                     </goals>                     <phase>compile</phase>                 </execution>                 <execution>                     <id>test-compile</id>                     <goals>                         <goal>testcompile</goal>                     </goals>                     <phase>test-compile</phase>                 </execution>                 <execution>                     <phase>process-resources</phase>                     <goals>                         <goal>compile</goal>                     </goals>                 </execution>             </executions>         </plugin>     </plugins> </build>  </project>