javagitmavenintellij-ideacode-formatting

How to format code according to google java format

Current state:

I have a project which is build with: Java 1.8.161, Maven 3.3.9, SpringBoot 2.0.1, tools: Jenkins and GitLab. I would like to use google java format as a standard for whole team.

My investigation / solution:

During the investigation I found solution, which sounds really easy. Just update pom file with:

<build>
    <plugins>
        <plugin>
            <groupId>com.coveo</groupId>
            <artifactId>fmt-maven-plugin</artifactId>
            <version>2.5.0</version>
            <executions>
                <execution>
                    <goals>
                        <goal>format</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

And it works. If I run compile, package, verify, install or deploy Maven lifecycle the code is formatted.

Question:

How can I run this after i.e. each commit for all team members without any extra steps in their IDEA? Because right now, I need to run Maven before each commit. But during the run of an application it is not necessary, so the team can avoid it.. Which of course will lead to problems with history in git.

Solution

  • You can let pre-commit hook trigger formatter for files staged for commit.

    git-code-format-maven-plugin uses google-java-format formatter and can install client-side pre-commit git hook during compile phase. It requires Maven 3.5.x, which should be enforced.

    <build>
  <plugins>
    <plugin>
      <groupId>com.cosium.code</groupId>
      <artifactId>git-code-format-maven-plugin</artifactId>
      <version>VERSION</version>
      <executions>
        <execution>
          <goals>
            <goal>install-hooks</goal>
          </goals>
        </execution>
      </executions>
    </plugin>
    <plugin>
      <artifactId>maven-enforcer-plugin</artifactId>
      <version>VERSION</version>
      <executions>
        <execution>
          <goals>
            <goal>enforce</goal>
          </goals>
          <configuration>
            <rules>
              <requireMavenVersion>
                <version>[3.5.4,)</version>
              </requireMavenVersion>
            </rules>
          </configuration>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

    Point to standalone Maven in IDE as git-code-format-maven-plugin does not play along nicely with embedded Maven.

    mvn compile to get hook installed. For IDEA, that's it.

    As git-code-format-maven-plugin only formats changed files (which is good), it is probably good to format whole project upfront once (mvn git-code-format:format-code -Dgcf.globPattern=**/*).

    Workaround for Eclipse

    Because of a bug in EGit, which sometimes ignores Git hooks completely, developers using Eclipse on Windows should have Cygwin in PATH. An empty cygpath.exe will do. Run 'Command Prompt' as a administrator and execute C:\>echo "" > /"Program Files"/Git/bin/cygpath.exe (kudos to hook is not working eclipse egit client).

    Reboot.

    A note on java import statements ordering

    Optimise imports or reformat in IDE or reformat with plugins, can lead to changes in imports ordering. A nasty surprise if an older version of git-code-format-maven-plugin is being used together with fmt-maven-plugin (to format or validate code later in CI, for example).