Clean Code in Java: A concise guide

Dec 6, 2023

Clean code is not just about making your program work; it’s about making your code readable, maintainable, and easily understandable by others. In Java, a language known for its verbosity, writing clean code becomes crucial for long-term success. In this brief guide, we’ll explore the principles of clean code through examples and tests in Java.

What is Clean Code?

Clean code is a style of writing code that prioritizes clarity, simplicity, and maintainability. It adheres to a set of principles that make the code easy to read and understand, reducing the chances of bugs and easing collaboration among developers. Some key principles include meaningful variable and method names, proper indentation, and avoiding unnecessary complexity.

Example 1: Meaningful Variable Names

// Unclean Code
int x = 10;
int y = 5;
int result = x + y;

// Clean Code
int baseNumber = 10;
int increment = 5;
int sum = baseNumber + increment;

Example 2: Proper Indentation

// Unclean Code
public void calculateTotal(int a, int b) {
return a+b;
}

// Clean Code
public int calculateTotal(int a, int b) {
    return a + b;
}

Example 3: Avoiding Unnecessary Complexity

// Unclean Code
public String getFormattedDate() {
    SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
    Date currentDate = new Date();
    String formattedDate = sdf.format(currentDate);
    return formattedDate;
}

// Clean Code
public String getCurrentDate() {
    DateTimeFormatter dtf = DateTimeFormatter.ofPattern("dd-MM-yyyy");
    return LocalDate.now().format(dtf);
}

Writing Tests for Clean Code

Writing tests is an integral part of maintaining clean code. Tests ensure that your code functions as expected and can catch potential issues early in the development process. Let’s take an example of a simple Java class and write tests for it using JUnit.

// Class to be tested
public class Calculator {
    public int add(int a, int b) {
        return a + b;
    }
}

// JUnit Test
import org.junit.Test;
import static org.junit.Assert.*;

public class CalculatorTest {
    @Test
    public void testAdd() {
        Calculator calculator = new Calculator();
        int result = calculator.add(3, 7);
        assertEquals(10, result);
    }
}