Top 25 Best Practices for Java Developers

I explained 25 best practices in this blog post, each illustrated with "Avoid" and "Better" examples, to guide Java developers toward writing more efficient, maintainable, and reliable code.

Java programming best practices cover a wide range of topics, from basic coding techniques to advanced features and design patterns. 
Top 25 Best Practices for Java Developers

1. Use Meaningful Variable Names

Avoid: Using unclear or generic variable names.

int a = 10;

Better: Use descriptive names that convey purpose.

int numberOfEmployees = 10;

Explanation: Descriptive names make code easier to read and understand.

2. Follow Java Naming Conventions

Avoid: Ignoring Java naming conventions.

String FirstName;
int orderamount;

Better: Follow Java's standard naming conventions.

String firstName;
int orderAmount;

Explanation: Following standard conventions improves readability and consistency.

3. Minimize Variable Scope

Avoid: Declaring variables before they are needed.

int result;
for (int i = 0; i < 100; i++) {
    result = i * 10;

Better: Declare variables close to where they are used.

for (int i = 0; i < 100; i++) {
    int result = i * 10;

Explanation: Narrow scope helps in understanding and maintaining the code.

4. Prefer Immutable Objects

Avoid: Designing classes that allow their internal state to be changed freely.

public class User {
    public String name; // Non-final public field

Better: Make classes and fields immutable where possible.

public class User {
    private final String name;

    public User(String name) { = name;

    public String getName() {
        return name;

Explanation: Immutable objects are simpler, safer, and inherently thread-safe.

5. Use Enums Instead of Constants

Avoid: Using public constants for enumerated types.

public static final int USER_ADMIN = 1;
public static final int USER_MEMBER = 2;

Better: Use enums to represent fixed sets of constants.

public enum UserType {

Explanation: Enums are more powerful, type-safe, and provide namespace.

6. Avoid Returning Nulls

Avoid: Returning null from methods, leading to potential NullPointerExceptions.

public String getUser(int id) {
    return null; // Dangerous practice

Better: Consider returning Optional or throwing exceptions.

public Optional<String> getUser(int id) {
    return Optional.empty();

Explanation: Using Optional avoids explicit null checks and makes the absence of a value explicit.

7. Handle Exceptions Appropriately

Avoid: Catching exceptions unnecessarily or too broadly.

try {
    // code
} catch (Exception e) {

Better: Catch specific exceptions and handle them properly.

try {
    // code
} catch (IOException e) {
    log.error("Error reading file", e);

Explanation: Proper exception handling prevents catching unintended exceptions and improves error recovery.

8. Avoid Magic Numbers

Avoid: Embedding literals directly in the code.

if (timeout == 30) {
    // process timeout

Better: Declare them as named constants.

private static final int DEFAULT_TIMEOUT = 30;

if (timeout == DEFAULT_TIMEOUT) {
    // process timeout

Explanation: Using named constants makes the code more readable and maintainable.

9. Prefer Early Exits

Avoid: Deep nesting of conditions.

if (condition) {
    // many lines of code

Better: Use early exits to reduce nesting.

if (!condition) return;
// code continues without nesting

Explanation: Early exits simplify the logic by reducing the cognitive load.

10. Use Collection Frameworks Appropriately

Avoid: Manually implementing data structures that are available in Java collections.

String[] array = new String[10]; // Limitations in size and utility

Better: Use Java Collections Framework for flexibility and functionality.

List<String> list = new ArrayList<>();

Explanation: Java collections provide dynamic sizing and a rich API for data manipulation.

11. Prefer Interface References

Avoid: Using concrete class types for collections and other container types.

ArrayList<String> list = new ArrayList<>();

Better: Use interface references to allow for flexibility.

List<String> list = new ArrayList


Explanation: Using interfaces as types makes it easier to change implementations.

12. Optimize Loops

Avoid: Unnecessary computations inside loops.

for (int i = 0; i < list.size(); i++) {
    // operations using list.size()

Better: Move invariant computations outside the loop.

int size = list.size();
for (int i = 0; i < size; i++) {
    // operations

Explanation: Reducing the workload inside loops can significantly enhance performance.

13. Document Public APIs

Avoid: Leaving public methods undocumented.

public void add(int a, int b) {
    // adds two numbers

Better: Use JavaDoc to document method behavior.

 * Adds two numbers.
 * @param a the first number
 * @param b the second number
 * @return the sum of a and b
public int add(int a, int b) {
    return a + b;

Explanation: Documentation helps other developers understand and use your methods correctly.

14. Use Access Modifiers Properly

Avoid: Leaving classes or members more accessible than necessary.

public String helper; // Should not be public

Better: Restrict access as much as possible.

private String helper;

Explanation: Proper use of access modifiers enhances encapsulation and security.

15. Prefer Readability Over Cleverness

Avoid: Using overly complex or "clever" code that is hard to understand.

public int calculate() {
    return // complex one-liner

Better: Write clear and understandable code.

public int calculate() {
    // step-by-step clear code
    return result;

Explanation: Clear code is easier to maintain, debug, and test than clever one-liners.

16. Avoid Premature Optimization

Avoid: Optimizing without profiling or evidence.

// complex code optimized based on assumptions

Better: Optimize based on profiling and actual performance needs.

// simple, clear code; optimize only if necessary

Explanation: Premature optimization can lead to complex, unreadable code that may not even address the true performance bottlenecks.

17. Regularly Refactor

Avoid: Allowing "code smells" to persist in the codebase.

// duplicated code, large classes, long methods

Better: Continuously refactor and improve code quality.

// clean, single-responsibility methods; DRY principles

Explanation: Regular refactoring keeps the codebase healthy and maintainable.

18. Write Unit Tests

Avoid: Writing code without tests.

public int multiply(int x, int y) {
    return x * y;

Better: Write comprehensive unit tests for your code.

public void testMultiply() {
    assertEquals(20, multiply(4, 5));

Explanation: Unit tests verify that your code works as expected and safeguard against future changes breaking functionality.

19. Follow SOLID Principles

Avoid: Writing code that violates object-oriented design principles.

public class UserManager {
    // user management, authentication, user logging

Better: Adhere to SOLID principles for robust and scalable code.

public class UserManager {
    // strictly user management

Explanation: SOLID principles ensure that your code is modular, interdependent, and scalable.

20. Avoid Static Methods for Utility Classes

Avoid: Using instance methods for classes that are essentially utility holders.

public class Utils {
    public void performAction() { ... }

Better: Use static methods in utility classes.

public class Utils {
    public static void performAction() { ... }

Explanation: Static methods in utility classes are easier to call and more appropriate for stateless operations.

21. Prefer Lambda Expressions and Streams

Avoid: Verbose anonymous classes for functional interfaces.

Runnable r = new Runnable() {
    public void run() {

Better: Use lambda expressions for conciseness and clarity.

Runnable r = () -> System.out.println("Running");

Explanation: Lambda expressions provide a clearer, more concise way to implement functional interfaces.

22. Ensure Thread Safety

Avoid: Ignoring concurrency issues in multi-threaded environments.

public class Counter {
    private int count = 0;

    public void increment() {

Better: Make

code thread-safe when necessary.

public class Counter {
    private AtomicInteger count = new AtomicInteger(0);

    public void increment() {

Explanation: Proper handling of concurrency ensures that your application functions correctly under all conditions.

23. Use Design Patterns Appropriately

Avoid: Applying design patterns where they are not needed.

// overly complex pattern usage for simple problem

Better: Use design patterns judiciously to solve specific problems.

// appropriate pattern usage where it clearly solves a problem

Explanation: Design patterns are tools, not goals; they should be used when they help simplify and solve specific design problems.

24. Automate Code Formatting

Avoid: Manually formatting code.

// inconsistent manual formatting

Better: Use tools to automatically format code.

// consistently formatted code via tools like IntelliJ IDEA or Eclipse

Explanation: Automated formatting ensures consistency and lets developers focus on logic rather than style.

25. Keep Learning and Updating Skills

Avoid: Sticking solely to what you know without learning new features or updates in the language.

// using only JDK 8 features in 2021

Better: Continuously update your knowledge with the latest Java features and best practices.

// using records, var, and other features from latest JDK releases

Explanation: Java is continuously evolving, and keeping up with the latest developments enables you to write more efficient, clean, and effective code.

By following these best practices, Java developers can ensure that they write code that is not only functional but also clean, maintainable, and efficient.