Integrating Scala into a Spring Boot Project

In this tutorial I will demonstrate how to integrate Scala into a Spring Boot Project.

Click on File->New->Project. Select 'Spring Initializr' and fill in the project details as follows:

For this project I have selected DevTools, Lombok, Web and Thymeleaf as initial dependencies:

Configure your project to support Scala by right-clicking on the project and selecting 'Add Framework Support'.

Select Scala:

Edit the pom.xml file as follows:

In the properties section, add:

<scala.version>2.12.0</scala.version>

Add the following dependencies:

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

Replace the existing Build section in pom.xml with the following code:

<build>
  <plugins>
    <plugin>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-maven-plugin</artifactId>
     </plugin>
    <plugin>
      <groupId>net.alchim31.maven</groupId>
      <artifactId>scala-maven-plugin</artifactId>
      <version>3.2.1</version>
      <executions>
        <execution>
          <id>compile-scala</id>
          <phase>compile</phase>
          <goals>
            <goal>add-source</goal>
            <goal>compile</goal>
          </goals>
        </execution>
        <execution>
          <id>test-compile-scala</id>
          <phase>test-compile</phase>
          <goals>
            <goal>add-source</goal>
            <goal>testCompile</goal>
          </goals>
        </execution>
      </executions>
      <configuration>
        <recompileMode>incremental</recompileMode>
        <scalaVersion>${scala.version}</scalaVersion>
        <args>
          <arg>-deprecation</arg>
        </args>
        <jvmArgs>
          <jvmArg>-Xms64m</jvmArg>
          <jvmArg>-Xmx1024m</jvmArg>
        </jvmArgs>
       </configuration>
    </plugin>
  </plugins>
</build>

Create a folder named "scala" under src/main.

Right click on the scala folder, and select 'Mark Directory as...' -> 'Sources Root'

Right-click on the scala folder to add a package, and within create a scala class:

package io.francoisbotha.sparkbuilder.sc
 
class GreetingInScala {
  def greet(): String = {
    val greeting = "Hello from SCALA!!!!"
    greeting
  }
}

Update the SparkBuilderAppliction file as follows:

package io.francoisbotha.sparkbuilder;
 
import io.francoisbotha.sparkbuilder.sc.GreetingInScala;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
 
@SpringBootApplication
public class SparkbuilderApplication {
 
  public static void main(String[] args) {
 
    GreetingInScala greetingInScala = new GreetingInScala();
 
    SpringApplication.run(SparkbuilderApplication.class, args);
 
    System.out.println(greetingInScala.greet());
 
  }
}

The code section above demonstrates how Scala classes can be integrated seamlessly in your Java Spring Boot project. The following is the output of running the application: