How to format code according to google java format

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).

• git-code-format-maven-plugin will sort imports (since version 1.20)
• fmt-maven-plugin will always sort imports
• googleformatter-maven-plugin can optionally sort imports (not per default)