在 Java Maven 依赖项中包含 Scala 项目

Question

Im new to scala, Im trying to include scala project into my java project. I have separate scala and java project and Im using scala in java.

It is working fine when I add scalaTest to my java project build path. Is there any way I can edit my pom.xml that automatically refer the scalaTest project while maven build?.

I have added scala dependency in my pom.xml

Or is there any way that I can include both java and scala files into my java project and run ?

Answer 1

If you the following pom.xml you should be able to compile Java and Scala sources from within the same project via mvn .

<?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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>javaScala</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>javaScala</name>

    <packaging>jar</packaging>

    <dependencies>
        <dependency>
             <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.11.7</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.scala-tools</groupId>
                <artifactId>maven-scala-plugin</artifactId>
                <version>2.15.2</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <sourceDir>src/main/scala</sourceDir>
                    <testSourceDir>src/test/scala</testSourceDir>
                    <jvmArgs>
                        <jvmArg>-Xms64m</jvmArg>
                        <jvmArg>-Xmx1024m</jvmArg>
                    </jvmArgs>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

Answer 2

Answers to my own question

1. Add Scala project in class path (buildpath) of java project.
2. Export Scala project as jar and import to your java project.

To include both java and scala in single java project, follow this.

Include java files into - src/main/java
Include scala files into - src/main/scala
Use this pom.xml

Download project from https://github.com/rthoma24/Java-Scala.git

maven commands

mvn compile
mvn exec:java -Dexec.mainClass=main.java.Test

<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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>ted-gao</groupId>
    <artifactId>scala-java-mix</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>Scala-Java mixture</name>
    <description>Showcase mixing Scala and Java</description>
    <packaging>jar</packaging>

    <build>
        <plugins>
            <!-- ensure that we use JDK 1.6 -->
            <plugin>
                <inherited>true</inherited>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>

            <plugin>
                <groupId>org.scala-tools</groupId>
                <artifactId>maven-scala-plugin</artifactId>
                <version>2.15.2</version>
                <executions>
                    <!-- Run scala compiler in the process-resources phase, so that dependencies on
                         scala classes can be resolved later in the (Java) compile phase -->
                    <execution>
                        <id>scala-compile-first</id>
                        <phase>process-resources</phase>                        
                        <goals>
                            <goal>compile</goal>
                        </goals>
                        </execution>

                        <!-- Run scala compiler in the process-test-resources phase, so that dependencies on
                             scala classes can be resolved later in the (Java) test-compile phase -->                    
                        <execution>
                        <id>scala-test-compile</id>
                        <phase>process-test-resources</phase>
                        <goals>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>build-helper-maven-plugin</artifactId>
                <executions>
                    <!-- Add src/main/scala to source path of Eclipse -->
                    <execution>
                        <id>add-source</id>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>add-source</goal>
                        </goals>
                        <configuration>
                            <sources>
                                <source>src/main/scala</source>
                            </sources>
                        </configuration>
                    </execution>

                    <!-- Add src/test/scala to test source path of Eclipse -->
                    <execution>
                        <id>add-test-source</id>
                        <phase>generate-test-sources</phase>
                        <goals>
                            <goal>add-test-source</goal>
                        </goals>
                        <configuration>
                            <sources>
                                <source>src/test/scala</source>
                            </sources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

            <!-- to generate Eclipse artifacts for projects mixing Scala and Java -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-eclipse-plugin</artifactId>
                <version>2.8</version>
                <configuration>
                    <downloadSources>true</downloadSources>
                    <downloadJavadocs>true</downloadJavadocs>
                    <projectnatures>
                        <projectnature>org.scala-ide.sdt.core.scalanature</projectnature>
                        <projectnature>org.eclipse.jdt.core.javanature</projectnature>
                    </projectnatures>
                    <buildcommands>
                        <buildcommand>org.scala-ide.sdt.core.scalabuilder</buildcommand>
                    </buildcommands>
                    <classpathContainers>
                        <classpathContainer>org.scala-ide.sdt.launching.SCALA_CONTAINER</classpathContainer>
                        <classpathContainer>org.eclipse.jdt.launching.JRE_CONTAINER</classpathContainer>
                    </classpathContainers>
                    <excludes>
                        <!-- in Eclipse, use scala-library, scala-compiler from the SCALA_CONTAINER rather than POM <dependency> -->
                        <exclude>org.scala-lang:scala-library</exclude>
                        <exclude>org.scala-lang:scala-compiler</exclude>
                    </excludes>
                    <sourceIncludes>
                        <sourceInclude>**/*.scala</sourceInclude>
                        <sourceInclude>**/*.java</sourceInclude>
                    </sourceIncludes>
                </configuration>
            </plugin>

            <!-- When run tests in the test phase, include .java and .scala source files -->
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.8.1</version>
                <configuration>
                    <includes>
                        <include>**/*.java</include>
                        <include>**/*.scala</include>
                    </includes>
                </configuration>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>org.scala-lang</groupId>
            <artifactId>scala-library</artifactId>
            <version>2.9.0</version>
        </dependency>
    </dependencies>
</project>

If mvn install/compile gives any error, delete your m2 directory and try again.