Automatically enforce code formatting in Maven projects

May 07, 2025

Put this plugin in your POM file:

<plugin>
  <groupId>com.diffplug.spotless</groupId>
  <artifactId>spotless-maven-plugin</artifactId>
  <version>${spotless-maven-plugin.version}</version>
  <configuration>
    <pom>
      <sortPom>
        <expandEmptyElements>false</expandEmptyElements>
        <keepBlankLines>false</keepBlankLines>
        <endWithNewline>true</endWithNewline>
      </sortPom>
    </pom>
    <java>
      <removeUnusedImports/>
      <googleJavaFormat>
        <version>${google-java-format.version}</version>
        <style>GOOGLE</style>
        <reflowLongStrings>true</reflowLongStrings>
        <formatJavadoc>true</formatJavadoc>
      </googleJavaFormat>
    </java>
  </configuration>
  <executions>
    <execution>
      <id>check-code-formatting</id>
      <goals>
        <goal>check</goal>
      </goals>
      <phase>process-sources</phase>
    </execution>
  </executions>
</plugin>

As of writing this, I'm using:

<spotless-maven-plugin.version>2.44.4</spotless-maven-plugin.version>
<google-java-format.version>1.26.0</google-java-format.version>

This plugin will enforce Google's Java format on your code, and it will run these checks during the process-sources phase, which happens just before: generate-resources -> process-resources -> compile, and just after generate-sources.