Porting a Maven Java project that uses JavaCC to Scala

Question

I am trying to port a Maven based Java project that uses JavaCC to Scala. I am happy to leave the JavaCC generated classes in Java at least for now. However the JavaCC generated class depends on the classes being converted.

The project builds fine from the original Java sources, but if I replace them with the Scala sources Maven tries to compile the JavaCC generated class first and does not see and of the symbols provided by the new code.

The problem then seems to be how to get Maven to generate the Java code first then compile the Scala code and the generated code together that the compiler can find all dependencies. The solution seems to be to add some magical incantation to pom.xml. What should that be though?

My current pom.xml is:

<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>bobj</groupId>
    <artifactId>bobj</artifactId>
    <version>0.9</version>
    <packaging>jar</packaging>

    <name>BOBJ algebraic specification and verification system</name>
    <url>http://github.com/fh-wedel/BOBJ</url>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <profiles>
        <profile>
            <id>scala-2.10</id>
            <properties>
                <scalaVersion>2.10.4</scalaVersion>
                <scalaBinaryVersion>2.10</scalaBinaryVersion>
            </properties>
            <dependencies>
                <dependency>
                    <groupId>org.scala-lang</groupId>
                    <artifactId>scala-library</artifactId>
                    <version>${scalaVersion}</version>
                </dependency>
                <dependency>
                    <groupId>org.scala-lang</groupId>
                    <artifactId>scala-swing</artifactId>
                    <version>${scalaVersion}</version>
                </dependency>
            </dependencies>
        </profile>
    </profiles>

    <build>
        <sourceDirectory>src/main/java</sourceDirectory>
        <plugins>
            <plugin>
                <artifactId>maven-jar-plugin</artifactId>
                <version>2.4</version>
                <configuration>
                    <archive>
                        <manifest>
                            <mainClass>bobj.BOBJ</mainClass>
                        </manifest>
                    </archive>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>javacc-maven-plugin</artifactId>
                <version>2.6</version>
                <executions>
                    <execution>
                        <id>javacc</id>
                        <goals>
                            <goal>javacc</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.6</source>
                    <target>1.6</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>net.alchim31.maven</groupId>
                <artifactId>scala-maven-plugin</artifactId>
                <version>3.1.6</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>testCompile</goal>
                        </goals>
                    </execution>
                </executions>
                <configuration>
                    <args>
                        <!-- work-around for https://issues.scala-lang.org/browse/SI-8358 -->
                        <arg>-nobootcp</arg>
                    </args>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.codehaus.mojo</groupId>
                <artifactId>build-helper-maven-plugin</artifactId>
                <version>1.9.1</version>
                <executions>
                    <execution>
                        <id>add-source</id>
                        <phase>generate-sources</phase>
                        <goals>
                            <goal>add-source</goal>
                        </goals>
                        <configuration>
                            <sources>
                                <source>src/main/scala</source>
                                <source>src/main/javacc</source>
                            </sources>
                        </configuration>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

    <dependencies>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.8.2</version>
            <scope>test</scope>
        </dependency>
    </dependencies>
</project>

I did not write this. I started with the pom.xml that came with the project and and added the parts for scala and build-helper-maven-plugin which I copied from other sources. My Maven-fu is minimal so I would not be surprised if I am doing something deeply misguided.

Answer 1

It turns out I forgot set up the scala-maven-plugin declaration for a mixed scala java project

ie the scala-maven-plugin needs

            <executions>
                <execution>
                    <id>scala-process-resources</id>
                    <phase>process-resources</phase>
                    <goals>
                        <goal>add-source</goal>
                        <goal>compile</goal>
                    </goals>
                </execution>
                <execution>
                    <id>scala-process-test-resources</id>
                    <phase>process-test-resources</phase>
                    <goals>
                        <goal>testCompile</goal>
                    </goals>
                </execution>
            </executions>

instead of the usual

            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>testCompile</goal>
                    </goals>
                </execution>
            </executions>