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Sunday, November 20, 2016

Common Java Code Review Comments

While working on a mobile application project, I joined a team with an aggressive release timeline and a highly autonomous development culture. Developers were able to merge changes freely, and formal code reviews, unit tests, and integration tests were not yet part of the standard workflow. Validation largely depended on a Quality Assurance (QA) team focused on end-to-end testing and defect reporting.

With a production release scheduled within two weeks, it quickly became clear that improving code quality and reducing risk before release would be critical. As a new team member, I spent time understanding the existing processes, identifying opportunities for improvement, and asking teammates where I could add the most value.

Rather than making assumptions or pushing abrupt changes, I focused on contributing in a way that aligned with the team’s immediate needs and timelines.

Introducing Lightweight Code Review Standards

Together with a colleague who had also transitioned from a previous project, we introduced a more structured but practical code review approach. The goal was not to slow development, but to:

  • Improve maintainability and readability
  • Reduce avoidable bugs before QA
  • Encourage shared ownership of code quality
  • Establish clear, consistent review expectations

To support this, I created a code review checklist that reviewers could use as a reference when evaluating pull requests. This checklist helped ensure that feedback was consistent, objective, and focused on engineering best practices rather than personal preferences.

Practical Code Review Checklist for Java Projects

Below is the checklist I used and refined over time. It’s intended as a guideline, not a rigid rulebook.

Documentation & Readability

  • Ensure Javadoc is present for public classes and methods
  • Update Javadoc when:
    • Method names change
    • Parameters change
    • Return types change
    • Business logic changes
  • Verify class and method names are descriptive and domain-specific
  • Check spelling and grammar in code comments and documentation

API & Design Quality

  • Use appropriate access modifiers (avoid unnecessary public)
  • Avoid returning null where Optional or empty collections are appropriate
  • Avoid returning overly large objects when smaller DTOs suffice
  • Eliminate duplicate or copy-pasted code through reuse or refactoring
  • Avoid deeply nested if statements—refactor for clarity

Error Handling & Logging

  • Do not swallow exceptions; handle or rethrow them appropriately
  • Ensure exceptions are logged with meaningful context
  • Use correct logging levels (INFO, WARN, ERROR, etc.)
  • Avoid overly verbose logs or logging large objects
  • Use clear, actionable error messages

Security & Data Protection

  • Never store unencrypted credentials or secrets in the repository
  • Review logging statements to ensure sensitive data is not exposed

Testing Practices

  • Ensure unit tests exist for new or modified functionality
  • Verify tests cover more than just happy-path scenarios
  • Validate edge cases and error handling paths
  • Flag incomplete or missing tests early

Framework & Utility Best Practices (Spring-Based Projects)

  • Prefer utility methods like:
    • CollectionUtils.isNotEmpty(...)
    • StringUtils.isBlank(...)
  • Avoid manual null and size checks when framework utilities are available

Pull Request Quality

  • Pull requests should include:
    • Clear descriptions of changes
    • Context for reviewers
    • Any known risks or follow-ups

Outcomes and Takeaways

This lightweight checklist helped:

  • Standardize feedback across reviewers
  • Improve code consistency
  • Reduce avoidable defects before QA testing
  • Create a more collaborative review culture

Most importantly, it demonstrated that code quality improvements don’t always require heavy process changes. Even small, well-communicated guidelines can make a meaningful difference—especially under tight deadlines.

Final Thoughts

Code reviews are not about gatekeeping—they’re about shared learning, maintainability, and protecting the product. This experience reinforced the value of clear standards, respectful collaboration, and incremental improvement.

I hope this checklist is useful for Java developers and teams looking to strengthen their code review practices without slowing delivery.

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