Java Code Review Checklist - Rishan Solutions

A thorough code review is essential for ensuring that your Java code is maintainable, efficient, and follows best practices. Below is a Java code review checklist that can be used to evaluate code quality and ensure adherence to industry standards.

1. Code Formatting and Readability

Indentation: Ensure consistent indentation (typically 4 spaces per level).
Braces: Verify that opening braces { are placed on the same line as the method, loop, or conditional statement.
Line Length: Ensure lines do not exceed the maximum length (typically 80 or 120 characters).
Spacing: Check for consistent spacing around operators and after commas.
Naming Conventions: Ensure variables, methods, and class names adhere to Java naming conventions (camelCase for variables and methods, PascalCase for classes, and UPPERCASE for constants).
Commenting: Verify that complex logic is well-documented with inline comments or JavaDoc comments for public methods and classes.
No Debugging Code: Make sure there is no leftover debugging code such as System.out.println.

2. Code Structure and Design

Single Responsibility Principle (SRP): Ensure that each class or method has only one reason to change and performs a single responsibility.
Method Length: Ensure methods are not too long (ideally less than 20-30 lines). Break down large methods into smaller, focused ones.
Class Length: Classes should be appropriately sized. If a class exceeds 500 lines, consider splitting it into smaller classes.
Code Duplication: Look for and eliminate any duplicate code. Reuse methods or consider creating helper classes if needed.
Design Patterns: Verify that appropriate design patterns are used, like Singleton, Factory, Observer, Strategy, etc.
Modularity: Ensure that the code is modular, meaning that classes and methods are loosely coupled and highly cohesive.

3. Readability and Maintainability

Descriptive Names: Ensure variables, methods, and class names are descriptive and easy to understand. Avoid using short or ambiguous names.
Comments and Documentation: Ensure that JavaDoc is used for public classes and methods, explaining their purpose, parameters, and return values.
Code Flow: Check for clear and easy-to-follow code flow. Avoid complex and deep nesting of logic.
Avoiding Magic Numbers: Make sure that any constant values are named and placed in constants or configuration files rather than hardcoded into the code.

4. Error Handling and Logging

Exception Handling: Ensure exceptions are properly caught and handled. Avoid catching generic exceptions (e.g., Exception or Throwable).
Custom Exception Classes: If needed, create custom exceptions with meaningful names that clearly convey the error.
Logging: Ensure that logging is in place at appropriate levels (e.g., DEBUG, INFO, ERROR) and avoids excessive or unnecessary logging. Use a standard logging framework like SLF4J, Log4j, or Logback.
Logging Information: Ensure that logs include useful information, such as method names, variable values, and error messages.

5. Performance Considerations

Efficiency: Ensure that the code is optimized for performance where applicable (e.g., avoid unnecessary loops or excessive database queries).
Memory Usage: Check for potential memory leaks, especially in case of large collections or objects that are not properly cleaned up.
Avoiding null: Minimize the use of null references and consider using Optional where appropriate to prevent NullPointerException.
Concurrency: If the code involves concurrency, ensure thread safety and proper synchronization (e.g., use synchronized, Atomic classes, etc.).

6. Unit Testing

Test Coverage: Ensure that all new or modified code has sufficient test coverage (typically over 80%).
Test Cases: Verify that unit tests check for both expected behavior and edge cases.
Mocking: If using mocks, ensure that they are used correctly (e.g., avoid unnecessary or overly complicated mocks).
Test Method Names: Ensure that test methods are named clearly and reflect the behavior being tested (e.g., testMethodName_whenCondition_thenExpectedResult).
Avoiding Tests for Implementation Details: Tests should focus on the behavior of the code rather than its implementation details.
Test Data Isolation: Tests should not depend on external systems or previous tests. Use mocks or test doubles for dependencies (e.g., databases, APIs).

7. Security Considerations

SQL Injection: Ensure that any SQL queries are properly sanitized or use prepared statements to prevent SQL injection.
Input Validation: Ensure that inputs from users or external systems are validated and sanitized to prevent injection attacks, XSS, etc.
Password Handling: Ensure that passwords are securely hashed and never stored in plain text (e.g., use bcrypt, PBKDF2).
Sensitive Information: Ensure that sensitive information like API keys, passwords, and tokens are not hardcoded or exposed in logs.
Access Control: Ensure that proper authentication and authorization checks are in place for sensitive operations.

8. Dependency Management

Dependencies: Ensure that the project uses the appropriate dependencies (i.e., avoid unnecessary or outdated dependencies).
Version Management: Ensure that dependencies are up-to-date and use version control best practices (e.g., in pom.xml or build.gradle files).
Transitive Dependencies: Check for unnecessary transitive dependencies and try to minimize them.
Spring Beans: For Spring applications, ensure that Spring beans are configured properly, and avoid excessive use of @Autowired where possible (consider constructor injection instead).

9. Testing for Edge Cases and Negative Scenarios

Boundary Conditions: Verify that the code handles boundary conditions and edge cases correctly (e.g., empty strings, zero, negative numbers).
Error Handling in Tests: Ensure that the code fails gracefully and provides meaningful error messages when invalid input or conditions are encountered.
Concurrency and Multi-threading: Verify that multi-threaded code behaves correctly, including handling race conditions and thread synchronization issues.

10. Compliance with Industry Standards

Coding Guidelines: Ensure that the code adheres to any internal coding guidelines or industry standards (e.g., Google Java Style Guide, Oracle’s Java Code Conventions).
Code Quality Tools: Use tools like SonarQube, Checkstyle, or PMD to ensure that the code meets quality standards.
Build Tools: Ensure that the code builds correctly with tools like Maven or Gradle, and that there are no compilation issues.

11. Continuous Integration and Deployment (CI/CD)

CI Setup: Ensure that the project has a properly configured CI/CD pipeline (e.g., Jenkins, GitLab CI, CircleCI) for automated builds, tests, and deployments.
Build Failures: Ensure that build failures are addressed promptly, and that the team does not push broken code into production.

12. Refactoring

Code Smells: Look for any signs of code smells such as large classes, long methods, deep inheritance trees, and excessive coupling.
Refactor Opportunities: Identify areas where code can be refactored for better readability, maintainability, and performance.
Test Refactoring: When refactoring code, ensure that unit tests are also updated accordingly.