Java Comments

In computer programming, comments are a portion of the program that are completely ignored by Java compilers. They are mainly used to help programmers to understand the code. For example,

// declare and initialize two variables
int a =1;
int b = 3;

// print the output
System.out.println("This is output");

Here, we have used the following comments,

• declare and initialize two variables
• print the output

---

Types of Comments in Java

In Java, there are two types of comments:

• single-line comment
• multi-line comment

---

Single-line Comment

A single-line comment starts and ends in the same line. To write a single-line comment, we can use the // symbol. For example,

// "Hello, World!" program example
 
class Main {
    public static void main(String[] args) {    	
        // prints "Hello, World!"
        System.out.println("Hello, World!");
    }
}

Run Code

Output:

Hello, World!

Here, we have used two single-line comments:

• "Hello, World!" program example
• prints "Hello World!"

The Java compiler ignores everything from // to the end of line. Hence, it is also known as End of Line comment.

---

Multi-line Comment

When we want to write comments in multiple lines, we can use the multi-line comment. To write multi-line comments, we can use the /*....*/ symbol. For example,

/* This is an example of  multi-line comment.
 * The program prints "Hello, World!" to the standard output.
 */

class HelloWorld {
    public static void main(String[] args) {

        System.out.println("Hello, World!");
    }
}

Run Code

Output:

Hello, World!

Here, we have used the multi-line comment:

/* This is an example of multi-line comment.
* The program prints "Hello, World!" to the standard output.
*/

This type of comment is also known as Traditional Comment. In this type of comment, the Java compiler ignores everything from /* to */.