What are Java Block Comments?

In Java, block comments are used to provide descriptive information about a block of code. They are also known as multi-line comments, as they can span multiple lines of code. Block comments in Java are enclosed within /* and */ characters. They are useful for providing descriptive information about a block of code or temporarily disabling code.

This guide will offer the following content:

What are Java Block Comments?
How Do Block Comments Work in Java?

What are Java Block Comments?

Java Block Comments are a way to add comments to your Java code. These blocks are not executed by the compiler, and they are simply ignored by the interpreter. Java Block Comments are a useful way to provide additional information about your code.

How Do Block Comments Work in Java?

Majorly, three types of comments are utilized in Java: single-line comments, Javadoc comments, and multi-line comments. In this explanation, we will focus on multi-line/block comments. They begin with /* and end with */ and can have multiple code lines.

Example 1: Provide Documentation About a Class or Method

Block comments are often used to provide documentation about a class or method. Here is an example of a block comment in Java:

/*
* This program prints "Hello, World!" to the console.
* Author: Syed Minhal Abbas
* Date: April 18, 2023
*/
public class Office {
public static void main(String[] args) {
System.out.println("Hello, World!"); // Print the greeting to the console
}
}

In this example, the block comment provides information about the purpose of the program, the author, and the date it was created. The comment gives a concise explanation of the main() method.

Example 2: Temporarily Disable Code

Block comments can be utilized to disable code temporarily. This is often called “commenting out” code. To do this, users simply surround the code to disable the code via /* and */ symbols. Here is an example:

public class HelloWorld {
public static void main(String[] args) {
/*
System.out.println("Hello, World!");
System.out.println("This code is disabled.");
*/
System.out.println("This code is enabled.");
}
}

In this example, the two “System.out.println()” statements are surrounded by block comments, which disables them. The third “System.out.println()” statement is not commented out, so it will be executed.

Note: It is important to note that block comments cannot be nested. If users want to comment out a block of code that contains a block comment, users will need to use a different type of comment, such as a single-line comment.

Conclusion

Java Block comments begin with /* & end with */. The compiler interprets everything as a comment and ignores everything between these two symbols. Block comments can span multiple code lines, making them beneficial for adding descriptions to the code. This is known as “commenting out” code. This guide has covered Java block comments in detail with practical implementation.