Code review checklist for Java developers

High Cohesion and Loose Coupling

Design Patterns - DRY and SRP

is there a potential for useful abstractions

Do not create adhoc threads, instead use shared Executors wherever possible.

Immutability for better thread-safety.

Synchronize access to shared mutable data.

Use non-blocking libraries and framework (webflux, kotlin coroutines), where needed.

Time and Memory complexity of the code.

Release resources after use (File Handles, db connections, etc)

Avoid dynamic SQL, use prepared statements

Proper error handling for negative scenarios, input should be validated before any processing.

Use checked exceptions for recoverable conditions and runtime exceptions for programming errors

Classes and methods should be small in terms of number of lines.

Explain yourself in the code.

Use Guava or Apache commons libraries wherever possible.

Did I grasp the concepts in a reasonable amount of time by looking at the code?

Meaningful naming convention, code should explain itself. Name of the variables, methods and classes should be intention revealing in nature.

Standard Code formatting across project

Code consistency with the existing culture of writing the code

Consistent method signatures (return optional instead of null for Java code)

Side effect on existing code, does this change break backward compatibility? Versioing of endpoint!

OWASP standards for the security

Do not log any sensitive information, neither put it into the query parameters.

Whether synchronous inter service communication can be avoided?

How to handle service invocation failures

Can we use non-blocking mechanism for inter service communication?

Using Pub/Sub or event driven approach instead of synchronous communication wherever possible