Java Code Review Check List

10 points checklist on Code Review

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

2) Is there any Side effect of this change: Sometimes one change in your system may cause a 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 the 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:  do 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 on 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 in 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 a 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 a review because failing on this point can lead your application crash and not able to recover from fault on other system or another part of the 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, the advantage of doing this is that you are using tried and tested code which reduces your QA time and also gives you more confidence. Introducing new libraries introduce a 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 makes excuse of time but believe me its worth to write it.