Code review is one of those things everyone agrees is important but few teams actually enjoy doing. It’s time-consuming, sometimes awkward, and often feels like a chore. But when done right? It’s one of the highest-leverage practices you can have in a Java team.
This guide is for teams who want to get serious about code quality — without slowing everything down. You’ll find real-world best practices, a practical checklist, and the kinds of things Java devs actually deal with in reviews. Whether your team is still growing or already shipping complex systems, this is for you.
Why Java Code Reviews Still Matter (a Lot)
Let’s get one thing out of the way: Java isn’t going anywhere. It’s still one of the most-used backend languages in the world. But it also comes with real complexity — verbose syntax, threading, exceptions, OOP patterns, dependency injection… you get the idea.
That’s exactly why Java code review matters.
A single method can span 80 lines and look totally fine at first glance. But dig deeper and you might find a silent performance hit, a concurrency risk, or just something that breaks your team’s internal conventions. Reviews catch those before they become production issues.
But they also do more than that:
- They help everyone understand more of the codebase
- They onboard new devs faster
- They reduce technical debt
- They prevent “only Alice knows how this works” situations
And maybe most importantly — they help teams build shared trust. That matters.
What Great Java Code Reviews Look Like
Before we get to the checklist, let’s talk about what good actually looks like. Because a code review is more than nitpicks and green checkmarks.
1. They’re focused
Great reviews don’t try to fix the entire codebase. They focus on the current change. They ask:
- Does this PR do what it’s supposed to do?
- Is it safe, readable, and maintainable?
- Are there edge cases we’re missing?
2. They’re specific
“Rename this var” isn’t helpful.
“This variable name doesn’t reflect what it actually holds — maybe call it parsedResult instead of temp?” is. Give context. Help your teammates understand why something’s worth changing.
3. They teach (and learn)
The best reviews are conversations. Not lectures. If you’re reviewing, your goal isn’t to “catch mistakes” — it’s to help the author make the code better, and to share knowledge in the process. Ask questions. Point to docs. Offer alternatives.
Java Code Review: The Essential Checklist
You don’t need to reinvent the wheel every time. This checklist covers what most reviewers should look for in any Java codebase. Copy, adapt, share with your team.
✅ Logic and Requirements
- Does the code do what the story or ticket says it should?
- Are edge cases handled (nulls, invalid input, concurrency)?
- Could this break existing functionality?
✅ Code Structure
- Are methods short and single-purpose?
- Are classes doing only one thing?
- Is the code easy to read and reason about?
✅ Style and Conventions
- Are naming conventions followed (
camelCase,PascalCase, constants inUPPER_SNAKE_CASE)? - Is formatting consistent?
- Are there unnecessary comments or TODOs left?
✅ Error Handling
- Are exceptions handled properly?
- Are we catching the right exceptions or swallowing stack traces?
- Are we logging sensitive information?
✅ Performance and Resources
- Any obvious inefficiencies (e.g., inside loops, unnecessary object creation)?
- Are streams, maps, and collections used correctly?
- Are resources (files, DB connections) being closed?
✅ Tests
- Are there tests for this change?
- Do the tests cover both expected and unexpected input?
- Would this break existing tests?
✅ Security (especially in web apps)
- Are inputs validated and sanitized?
- Are passwords/tokens stored or logged?
- Any potential injection or race condition risks?
Common Mistakes to Avoid in Java Code Review
Even experienced devs fall into these traps. Recognizing them early saves time (and frustration).
❌ The “it compiles, ship it” mindset
Passing tests are great. But they don’t catch:
- Bad variable names
- Code that’s impossible to extend
- Logic that “sort of” works… until it doesn’t
Your job as a reviewer isn’t to rubber-stamp. It’s to think critically.
❌ Giant PRs
We’ve all seen them. 500+ lines. 9 files. Impossible to review well.
Smaller is better. Aim for 100–300 line diffs. Make it easy to give thoughtful feedback.
❌ Style nitpicking
If your team has autoformatting tools (and you should), don’t waste time arguing about braces or spacing. Focus on logic, design, and impact.
❌ Reviewer-as-gatekeeper
Your job isn’t to prove you’re smarter. It’s to help your teammate ship better code. If something’s wrong, point it out respectfully — and offer help when you can.
Tips to Make Java Code Reviews Smoother (For Everyone)
You can have the best checklist in the world, but if your process is broken, nobody’s going to enjoy doing reviews.
Here are some battle-tested tips:
Keep PRs small
Seriously. This changes everything. Reviewers will give better feedback, faster.
Review early, review often
Don’t let PRs sit for two days. Give feedback while the context is fresh. If you’re the author, request review as soon as tests pass.
Use review tools properly
Leverage GitHub/GitLab features:
- Leave inline comments
- Suggest changes directly
- Tag specific teammates
Write good PR descriptions
Context matters. A one-liner like “Fix bug” doesn’t help. Briefly explain what’s changing and why. Link to related issues if relevant.
Celebrate improvements
Saw a smart solution or a thoughtful refactor? Say so. Reviews aren’t just about criticism — they’re a chance to recognize great work.
Java Code Review FAQ
What if I don’t understand the code I’m reviewing?
That’s okay. Ask questions. A good PR should be easy to follow. If it’s not, that’s a signal — not a you problem.
How long should I spend reviewing a PR?
Depends on size and complexity. A 200-line change? Maybe 15–20 minutes. Set a timer if needed. More than that? It’s probably too big.
Who should review the code?
Someone familiar with the domain is ideal. But everyone should be able to review most PRs. Rotate reviewers to avoid silos.
What if we disagree in a review?
Disagree respectfully. Use data or reference guides. Involve a third teammate if needed. Don’t let it become personal.
Can’t AI do code review now?
AI helps a lot — but doesn’t fully replace humans. It won’t always know your internal conventions or business logic. Think of it as a power-up, not a substitute.
Final Thoughts
Java code review isn’t just a gatekeeping process. It’s a way to build better software, together.
If you want your team to move faster and keep quality high, investing in reviews is one of the best decisions you can make. Start with the checklist above. Avoid the common traps. Keep your PRs small, your comments kind, and your focus on long-term maintainability.
And if your current review process feels like a mess? That’s normal. Most teams improve it gradually. You don’t need a perfect system — just one that keeps evolving.
Thanks for reading. Now go review that PR in your backlog.
Want to go deeper? Try using tools like Kodus to automate part of your Java code review workflow and free up your team to focus on the stuff that really matters.
Your future self will thank you.
