How to format code according to google java format in my github workflow with maven

Question

I have written this workflow below to verify the Java format in my project according to Google Java style guides. My intention is to use maven in the workflow.

    # Checks that the code is formatted according to the
    # Google Java style guide
    name: Code Formatter Check
    on:
      push:
        branches: [main]

      pull_request:
        branches: [main]
    jobs:
      build:
        runs-on: ubuntu-latest
        steps:
          - uses: actions/checkout@v2
          - name: Setup JDK 1.8
            uses: actions/setup-java@v1
            with:
              java-version: 1.8
              distribution: 'adopt'
              cache: maven
          - name: Build with maven
            run: mvn --batch-mode --update-snapshots verify verifyGoogleJavaFormat

With gradle I would have make it executable with chmod +x gradlew and run with ./gradlew verifyGoogleJavaFormat.

My question is how can I achieve this with maven. With above workflow I get the following error:

Unknown lifecycle phase "verifyGoogleJavaFormat".

Answer 1

You need to include a maven plugin that supports Googles Java format. It seems like your goal verifyGoogleJavaFormat is available for Gradle, but not for Maven. One option is to use https://github.com/Cosium/git-code-format-maven-plugin. It supports format verification and automatic formatting upon comitting.

The Github Repo documentation states that you can include it in your pom.xml like this:

<build>
    <plugins>
        <plugin>
            <groupId>com.cosium.code</groupId>
            <artifactId>git-code-format-maven-plugin</artifactId>
            <version>3.3</version>
            <executions>
                <!-- On commit, format the modified java files -->
                <execution>
                    <id>install-formatter-hook</id>
                    <goals>
                        <goal>install-hooks</goal>
                    </goals>
                </execution>
                <!-- On Maven verify phase, fail if any file
                (including unmodified) is badly formatted -->
                <execution>
                    <id>validate-code-format</id>
                    <goals>
                        <goal>validate-code-format</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Now, when I run mvn verify on my unformatted project I get an error:

[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  6.090 s
[INFO] Finished at: 2022-03-12T17:56:13+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.cosium.code:git-code-format-maven-plugin:3.3:validate-code-format (validate-code-format) on project javatest: /home/bisensee/repos/javatest/src/main/java/Position.java is not correctly formatted ! -> [Help 1] 

When we make our next commit the formatter is automatically applied via a Git hook and the next mvn verify succeeds.