Topic 4618 min readStructured Tutorial

Java Comments Explained

Quick Answer

Comments explains comments are an essential part of writing clear and maintainable Java code.

Learning Objectives

Explain the purpose of Comments in a practical learning context.
Identify the main ideas, terms, and decisions involved in Comments.
Apply Comments in a simple real-world scenario or practice task.

Introduction

Comments are an essential part of writing clear and maintainable Java code.

They help developers explain what the code does, making it easier to understand and maintain.

In this tutorial, you will learn about different types of comments in Java and how to use them properly.

Good code is its own best documentation.

What Are Comments in Java?

Comments are non-executable lines in the source code that are ignored by the Java compiler.

They are used to provide explanations, clarify complex code, or temporarily disable code during debugging.

Improve code readability
Help other developers understand your code
Document important information about the code

Types of Comments in Java

Java supports three types of comments: single-line, multi-line, and documentation comments.

Java Comment Types
Comment Type	Syntax	Description
Single-line Comment	// comment text	Comments a single line or part of a line.
Multi-line Comment	/* comment text */	Comments multiple lines or a block of code.
Documentation Comment	/** comment text */	Used to generate external documentation.

Single-line Comments

Single-line comments start with two forward slashes (//) and continue to the end of the line.

They are useful for brief explanations or notes.

Placed above or beside code lines
Cannot span multiple lines

Multi-line Comments

Multi-line comments start with /* and end with */.

Examples of Java Comments

Here are examples demonstrating each type of comment in Java.

Practical Example

This example shows documentation, single-line, and multi-line comments in a Java class.

Examples

Java Comments Example

public class CommentExample {
    /**
     * This is a documentation comment for the main method.
     * @param args Command line arguments
     */
    public static void main(String[] args) {
        // Print a welcome message
        System.out.println("Welcome to Java Comments Tutorial");
        /* This is a multi-line comment
           that spans two lines */
    }
}

This example shows documentation, single-line, and multi-line comments in a Java class.

Best Practices

Use comments to explain why code does something, not what it does.
Keep comments concise and relevant.
Update comments when you modify the code.
Use documentation comments for public APIs.
Avoid obvious comments that restate the code.

Common Mistakes

Writing outdated comments that no longer match the code.
Overusing comments instead of writing clear code.
Using comments to disable large blocks of code permanently.
Neglecting to document important methods or classes.

Hands-on Exercise

Add Comments to Code

Take a simple Java program and add single-line, multi-line, and documentation comments explaining the code.

Expected output: A Java program with clear and correct comments.

Hint: Identify key parts of the code and explain their purpose using appropriate comment types.

Interview Questions

What are the different types of comments in Java?

Interview

Java has three types of comments: single-line (//), multi-line (/* */), and documentation comments (/** */).

Why are comments important in Java programming?

Interview

Comments improve code readability, help other developers understand the code, and document important information.

What is Comments, and why is it useful?

Beginner

Comments are an essential part of writing clear and maintainable Java code.