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Kavitha Pazhanee
Kavitha Pazhanee

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Java Code Review Checklist: Best Practices for Clean and Maintainable Code

Introduction
Code reviews are essential for maintaining code quality in Java projects. They help teams identify bugs early, ensure maintainability, and enforce coding standards.

But without a checklist, reviews can become inconsistent. That’s why having a Java code review checklist makes the process smoother, more objective, and more effective.

In this guide, we’ll cover a complete Java code review checklist with examples.

✅ 1. Java Code Readability and Style
✔ Follow Java naming conventions, classes start with uppercase, methods & variables start with lowercase)(CamelCase for classes, camelCase for methods/variables).
✔ Use meaningful names (calculateInvoiceTotal > calcInv).
✔ Maintain consistent indentation and formatting.
✔ Avoid long methods (keep them focused).

📌 Example:

// ❌ Bad
public void p(int a, int b){int c=a+b;System.out.println(c);}

// ✅ Good
public void printSum(int number1, int number2) {
int sum = number1 + number2;
System.out.println(sum);
}
✅ 2. Object-Oriented Design Principles
✔ Ensure encapsulation (use private fields with getters/setters when necessary).
✔ Apply SOLID principles (especially Single Responsibility Principle).
✔ Prefer composition over inheritance.

📌 Example:

// ❌ Bad: unnecessary inheritance
class ElectricCar extends Engine { }

// ✅ Good: composition
class ElectricCar {
private Engine engine;
}
✅ 3. Exception Handling in Java
✔ Don’t swallow exceptions (avoid empty catch blocks).
✔ Use specific exceptions instead of catching Exception.
✔ Add meaningful error messages.
✔ Consider custom exceptions when applicable.

📌 Example:

// ❌ Bad
try {
processOrder();
} catch (Exception e) {
// ignored
}

// ✅ Good
try {
processOrder();
} catch (IOException e) {
log.error("Order processing failed due to IO issue", e);
}
✅ 4. Java Performance Best Practices
✔ Avoid creating unnecessary objects inside loops.
✔ Use StringBuilder for concatenation in loops.
✔ Be mindful of Streams API performance.
✔ Close database connections and streams properly.

📌 Example:

// ❌ Bad
String result = "";
for (String word : words) {
result += word;
}

// ✅ Good
StringBuilder sb = new StringBuilder();
for (String word : words) {
sb.append(word);
}
String result = sb.toString();
✅ 5. Java Security Checklist
✔ Never hardcode credentials or API keys.
✔ Validate all user inputs.
✔ Use PreparedStatement to prevent SQL Injection.
✔ Avoid logging sensitive information.

✅ 6. Testing and Maintainability
✔ Check for unit test coverage (JUnit, Mockito).
✔ Use meaningful test method names.
✔ Test edge cases and boundary values.
✔ Ensure code is modular and refactor-friendly.

📌 Example:

@test
void shouldReturnEmptyListWhenNoUsersFound() {
List users = userService.findUsersByRole("ADMIN");
assertTrue(users.isEmpty());
}
✅ 7. Dependency and Build Management
✔ Remove unused imports and dependencies.
✔ Keep dependencies updated (but stable).
✔ Avoid circular dependencies.
✔ Document external libraries in use.

🎯 Conclusion
A proper Java code review checklist ensures code is:

Readable and consistent
Secure and reliable
Performant and maintainable
By applying these best practices, your Java team can improve collaboration, reduce bugs, and deliver higher-quality software.

🛠️ Check out SonarLint for automated Java code quality checks

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