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Mixed Java and Scala Maven Projects

 

To compile code with mixed Java & Scala classes, add following to pom.xml 

<build>
		<pluginManagement>
			<plugins>
				<plugin>
					<groupId>net.alchim31.maven</groupId>
					<artifactId>scala-maven-plugin</artifactId>
					<version>4.8.1</version>
				</plugin>
				<plugin>
					<groupId>org.apache.maven.plugins</groupId>
					<artifactId>maven-compiler-plugin</artifactId>
					<version>3.8.1</version>
					<configuration>
                      <source>1.8</source>
                      <target>1.8</target>
                    </configuration>
				</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>
				<configuration>
                  <source>1.8</source>
                  <target>1.8</target>
                </configuration>
				<executions>
					<execution>
						<phase>compile</phase>
						<goals>
							<goal>compile</goal>
						</goals>
					</execution>
				</executions>
			</plugin>
		</plugins>
	</build>

Reference - 

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