Saturday, September 24, 2011

Code Review Checklist and Best practices in Java

What to review while doing Code review
Code Review and Unit testing is one of best development practice I always recommend, strive for and enforce as much as possible. Even just by doing code review and Junit test case always offer positive result it can be improved a lot by constantly learning with our mistakes , others mistakes and by observing how others are doing it. I always try to get my code review by some one with more experience so that I can capture any domain specific scenario which has been missed during think through process and some with less experience so that he can improve his code readability, have a four eye check and most importantly I found that when i explain my code to some one as part of code review I myself discover many things which can be improved or left out.Overall it always add something and improve code quality and reduce bug.


code review checklist, code review best practicesI also review some one else code and voluntary take part to improve my code understanding ability and offer help to others, In this article I will list things which I look while doing code review. These are the things which I have been accumulated over the years but I also look forward to you guys to contribute your experience, best practices for code review and suggest how you guys do code review. These tips are independent of language and equally apply to Java, .NET or C++ code.

10 points checklist on Code Review


1) Does Code meet functional requirement: first and foremost does code meets all requirements which it should met, point out if anything has been left out.

2) Is there any Side effect of this change: Some time one change in your system may cause bug in other upstream and downstream system and it’s quite possible that new developer or anyone who is writing code might not be available of that dependency. This often directly related to experience in project and I found that the more you know about system and its environment better you able to figure this out.

3) Concurrency: does code is thread-safe? Does it have properly synchronized if using shared resource? Does it free of any kind of deadlock or live-lock? Concurrency bugs are hard to detect and often surfaces in production. Code review is one place where you can detect this by carefully understand design and its implementation.

4) Readability and maintenance:  does code is readable? Or is it too complicate for some-one complete new. Always give value to readability as code is not just for this time it will remain there for long time and you need to read it many times. Another important aspect is maintenance as most of software spends 90% time in maintenance and only 10% time on development it should be maintainable and flexible in first place. You can verify that whether code is configurable or not, look for any hard coding, find out what is going to be changed in near future etc.

5) Consistency: This is part of point 4 but I have made it another separate point because of its importance. This is the best thing you can have in your code which automatically achieves readability. Since many developer and programmer take part in project and they have there own style of coding, it’s in best interest of everybody to form a coding standard and follow it on letter and spirit. For example it’s not good someone using function initialize() and other is using init() for same kind of operation, keep you code consistent and it will look better, read better.

6) Performance: Another important aspect most important if you are writing high volume low latency electronic trading platform for high frequency trading which strives for micro second latency. Carefully monitor which code is going to execute at start-up and which is going to be executed in loop or multiple times, optimize the code which is going to execute more often.

7) Exception handling: Ask does code handles bad input and exception? It should and that too with predefined and standard way which must be available and documented for support purpose. I put this point well above on my chart while doing review because failing on this point can lead your application crash and not able to recover from fault on other system or other part of same application.

8) Simplicity: Always see if there is any simple and elegant alternative available at-least give a thought and try. Many times first solution comes in mind is not best solution so giving another thought is just worth it.

9) Reuse of existing code: See if the functionality can be achieved by using existing code, advantage of doing this is that you are using tried and tested code which reduce your QA time and also give you more confidence. Introducing new libraries introduce new dependency. I prefer not to try anything fancy until it’s absolutely necessary.


10) Unit test: Check whether enough JUnit test cases have been written and cover sufficient percentage of new code. never let you pass the code without Junit test because developer often make excuse of time but believe me its worth to write it.

Not last but least that put a comment on your java file that by whom it has been reviewed, what issue finds are out and status of those. This will make the whole process official and ensures that due diligence would be applied during code review. Its also good to maintain your own code review checklist or a project wise code review checklist and use it every time while doing review. There are so many best practices but I have only included those which I follow and found interesting but as I had said earlier this is the area which always needs improvement and no body is perfect on that. So please contribute your ideas on code review and effective development.

Enjoy

Some older post you may like

3 comments :

Javin @ String split Java said...

Thanks for your comment itoctopus, I agree Concurrency issues are more subtle and most of the time only shows in production due to high volume and different real world, one way to deal with this is load testing which reveals some concurrency issues.

Anonymous said...

I am big fan of Code reviews and spend more time convincing people to do Code reviews than actually doing them :). While I am here, I would like to share couple of benefits of Code review, which I have personally seen.

1) Code review can be a real team building exercise, It increase and improves communication between team members. Though Code review must be given only keeping positives in mind, instead of criticizing other developer.

2) Code review also increase knowledge sharing between team, which means, whole team remains in same page and ready to backup each other. This can be a huge plus for Manager, who needs to manage leaves and resources.

3) Ultimately benefit of Code review is better code quality, reduce testing time and less number of bugs. There is no substitute of Code review.

Now What can go wrong with Code review:

Like anything else Code review also has two sides of Coin, if not done properly it can harm the team. feedback must always be constructive, It's responsibility of Senior develop to educate team and encourage them learn and think through. Code reviewer should never think that he has to find flaws, he can also appreciate fellow developer. Keeping things simple and normal is key to success.

Tom Henricksen said...

Along the lines of "Readability and maintenance" I would include clean code changes like suggested by Robert C Martin in his book, "Clean Code". These are all good tips to keep in mind when we do a code review.

Post a Comment