[DISCUSSION ONLY - DO NOT MERGE] Added CheckStyle and Spotless plugins for code checking and formatting

[sunyuhan1998]

We need to add a code style checking and automatic formatting plugin to unify the code style and automatically handle common formatting issues.

In this PR, the Checkstyle and Spotless plugins have been introduced. For Checkstyle, only some of the previously discussed rules have been included in the rule file src/checkstyle/checkstyle.xml, such as disallowing importing unused classes and disallowing wildcard imports. More rules can be added in the future if needed.

As for Spotless, it is currently using the default rules. Both plugins run during the Maven validate phase.

You can directly run mvn clean validate to trigger the checks from both plugins, and run mvn spotless:apply to trigger Spotless to automatically format the code.

@kabir Do you think this direction aligns with what we're hoping for?

[gemini-code-assist]

Summary of Changes

Hello @sunyuhan1998, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request is a discussion-only proposal to integrate code style checking and automatic formatting tools into the project. My goal is to establish a consistent code style across the repository and provide mechanisms for developers to easily adhere to it, improving readability and maintainability. It introduces Checkstyle for static analysis and Spotless for formatting, both integrated into the Maven build process.

Highlights

• Introduction of Code Quality Tools: I've introduced both Checkstyle and Spotless Maven plugins to enforce code style and enable automatic formatting. This aims to unify the codebase's appearance and reduce common formatting issues.
• Maven Integration: Both Checkstyle and Spotless are configured to run during the Maven validate phase. This ensures that style checks and formatting validations are performed early in the build lifecycle.
• Checkstyle Configuration: Checkstyle is configured with a custom rule set (src/checkstyle/checkstyle.xml) focusing initially on import-related rules, specifically disallowing wildcard imports, redundant imports, illegal imports, and unused imports. More rules can be added later as needed.
• Spotless Configuration: Spotless is set up to use Google Java Format with the AOSP style. It also includes a rule to automatically remove unused imports, providing basic code cleanup capabilities.
• Usage Instructions: To trigger the checks, mvn clean validate can be run. For automatic formatting via Spotless, mvn spotless:apply is available.

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[gemini-code-assist]

Code Review

This pull request introduces Checkstyle and Spotless to enforce code style and formatting, which is a great step for the project's maintainability. My review focuses on the Maven configuration for these new plugins. I've identified a few critical issues, such as incorrect plugin and dependency versions and a misconfigured path for the Checkstyle rules, which would cause build failures. I've also included suggestions to update to the latest tool versions and to simplify the Spotless configuration for better clarity. Addressing these points will ensure the new tools are set up correctly and effectively.

[kabir]

@sunyuhan1998 Just about to get on a plane, but will look later/tomorrow.

In the meantime, it could be good to see what kind of stuff it reports against the existing codebase. Maybe as a link to a gist, if it is very long :-)

[kabir]

BTW I converted the PR to a draft, so that it cannot be merged

[sunyuhan1998]

@sunyuhan1998 Just about to get on a plane, but will look later/tomorrow.

In the meantime, it could be good to see what kind of stuff it reports against the existing codebase. Maybe as a link to a gist, if it is very long :-)

Sure, no problem. This is just a rough experimental attempt. I think it will still take some time before we actually integrate it, and during that period we can further discuss and refine the plan in detail.