Maven plugin¶

The plugin formats the Java sources of a Maven build, or fails the build when they are not formatted. Maven has to run on Java 21 or later.

Add the plugin¶

<build>
    <plugins>
        <plugin>
            <groupId>dev.openjavaformat</groupId>
            <artifactId>fmt-maven-plugin</artifactId>
            <version>2.27.0.1</version>
            <executions>
                <execution>
                    <goals>
                        <goal>format</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>dev.openjavaformat</groupId>
                    <artifactId>open-java-format</artifactId>
                    <version>2.98.0.4</version>
                </dependency>
            </dependencies>
        </plugin>
    </plugins>
</build>

The format goal runs in the process-sources phase, so mvn compile, mvn test and every later phase format src/main/java and src/test/java first.

The dependency is not optional. The plugin does not bring a formatter of its own: it runs the open-java-format version named there, and without it the build stops with a message that says what to add. Name the same version as in your IDE and your other builds.

Check in CI¶

Use the check goal instead of format. It changes no file, and in the verify phase it fails the build when a file is not formatted:

[ERROR] Found 1 non-complying files, failing build
[ERROR] To fix formatting errors, run "mvn dev.openjavaformat:fmt-maven-plugin:format"

Run a goal from the command line¶

mvn dev.openjavaformat:fmt-maven-plugin:format
mvn dev.openjavaformat:fmt-maven-plugin:check

The plugin still has to be in the pom.xml with its dependency: Maven reads the dependencies of a plugin from the POM, never from the command line.

Options¶

The plugin is a fork of spotify/fmt-maven-plugin with open-java-format in place of google-java-format. Its options, such as extra source directories, file name patterns and skipping a directory, are listed in its README. There is nothing to set for the formatting itself: imports are always sorted and cleaned up, and long strings are always reflowed, as on every other route.