Java Comments

Back to: Java Tutorials

In Java, comments are pieces of text that are ignored by the compiler when it is building an application. They are used to provide information about the code, explain what it does, and make it easier for other programmers to understand. Java supports three types of comments:

1. Single-line comments: Single-line comments begin with two forward slashes (//). Anything that follows on the same line is ignored by the compiler. Here’s an example:

// This is a single-line comment

2. Multi-line comments: Multi-line comments begin with /* and end with */. Anything between these characters is ignored by the compiler. Multi-line comments can span multiple lines. Here’s an example:

/*
This is a multi-line comment
It can span multiple lines
*/

3. Javadoc comments: Javadoc comments are a special type of comment that begin with /** and end with */. They are used to generate documentation for the code. Javadoc comments can include special tags that provide information about the code, such as the author, version, and parameters. Here’s an example:

/**
 * This is a Javadoc comment. It is used to generate documentation for the code.
 *
 * @param name The name of the person to greet
 * @return A greeting string
 */
public String greet(String name) {
    return "Hello, " + name + "!";
}

Javadoc comments can be used to generate documentation using tools such as Javadoc. By including Javadoc comments in your code, you can make it easier for other programmers to understand how your code works and how to use it.

Code example of Java Comments:

/**
 * This is a Java program that demonstrates the use of comments.
 */
public class CommentsExample {

    /**
     * This is the main method of the program.
     */
    public static void main(String[] args) {
        // This is a single-line comment
        System.out.println("Hello, world!"); // This is another single-line comment

        /*
         * This is a multi-line comment. It can span multiple lines.
         * Here's another line of the comment.
         */
        int x = 10;

        // Let's print the value of x
        System.out.println("The value of x is: " + x);

        // Now let's change the value of x
        x = 20;

        // And print the new value of x
        System.out.println("The new value of x is: " + x);
    }

    /**
     * This method greets the specified person by name.
     *
     * @param name The name of the person to greet
     * @return A greeting string
     */
    public String greet(String name) {
        return "Hello, " + name + "!";
    }
}

In this example, you can see the three types of comments in Java:

1. Single-line comments: These are used to provide a brief explanation of the code on the same line. For example, in the main method, there are two single-line comments.
2. Multi-line comments: These are used to provide more detailed explanations that span multiple lines. For example, in the main method, there is a multi-line comment that explains the purpose of the code.
3. Javadoc comments: These are used to generate documentation for the code. In the example, the greet method has a Javadoc comment that explains the purpose of the method, its parameters, and its return value.

Note:

In general, it’s a good practice to include comments in your code to make it more readable and maintainable. When writing comments, be sure to use clear and concise language, and explain any complex or non-obvious code. This can help to make your code more accessible to other programmers and improve the overall quality of your code.

Also, see the example code JavaExamples_NoteArena in our GitHub repository. See complete examples in our GitHub repositories.

Follow us on social media

Follow Author