[JAVA] Automate format with maven-formatter

Introduction

Originally, each team member set the format in the IDE and performed the format. It would be nice if it was automatically formatted when pushed to github. So I introduced it, so I will summarize the method.

1. maven settings

This time, we will use formatter-maven-plugin.

1.1. Added plugin to pom.xml.

<project ...>
    ...
    <plugins>
      <plugin>
        <groupId>net.revelc.code.formatter</groupId>
        <artifactId>formatter-maven-plugin</artifactId>
        <version>2.11.0</version>
      </plugin>
    </plugins>
    ...
</project>

After setting, you can execute format or validate with the following command.

//Run format
mvn formatter:format
//check
mvn formatter:validate

1.2. Directory settings

When specifying a directory other than src / main / java or src / test / java

<plugin>
  <groupId>net.revelc.code.formatter</groupId>
  <artifactId>formatter-maven-plugin</artifactId>
  <version>2.11.0</version>
  <configuration>
    <directories>
      <directory>${project.build.sourceDirectory}</directory>
      <directory>${project.build.directory}/generated-sources</directory>
    </directories>
  </configuration>
</plugin>

When specifying a directory or file in src / main / java or src / test / java

--includes: Directories and files you want to target --exclus: Directories and files you want to exclude ** Note: Write properly up to / **

<plugin>
  <groupId>net.revelc.code.formatter</groupId>
  <artifactId>formatter-maven-plugin</artifactId>
  <version>2.11.0</version>
  <configuration>
    <includes>
      <include>jp/****/****/****/formatter/</include>
    </includes>
    <excludes>
      <exclude>jp/relativitas/maven/plugins/formatter/special/</exclude>
      <exclude>**/*Test.java</exclude>
    </excludes>
  </configuration>
</plugin>

1.3. Format file settings

To make your own format settings, you need to specify an Eclipse format configuration file. The recommendation is format published by google.

<plugin>
  <groupId>net.revelc.code.formatter</groupId>
  <artifactId>formatter-maven-plugin</artifactId>
  <version>2.11.0</version>
  <configuration>
    <configFile>${project.basedir}/eclipse-java-google-style.xml</configFile>
  </configuration>
</plugin>

2. Github Actions settings

2.1. Creating a YAML file

Create a YAML file in .github / workflows /. The execution contents are the following three. --Code format --Check after format --commit the formatted code

 name: auto-format
on:
  push:
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Set up JDK 1.8
        uses: actions/setup-java@v1
        with:
          java-version: 1.8
      - name: format
        run: |
          mvn formatter:format
          mvn formatter:validate
      - uses: stefanzweifel/[email protected]
        with:
          commit_message: Formatted code

in conclusion

With the above settings, a commit with format will be created when you push the code to github. This will prevent you from forgetting the format locally, and you can comfortably perform code reviews.