Java Comments

Comments are notes inside the code. The compiler ignores them. They help other people (and you after six months) to understand the code.

Single line comment

Starts with // and goes to the end of the line.

public class Main {
    public static void main(String[] args) {
        // This line is only a comment
        System.out.println("Hello"); // comment after code
    }
}

Multi line comment

Starts with /* and ends with */.

public class Multi {
    public static void main(String[] args) {
        /* This is a comment
           on more than one line. */
        System.out.println("Done");
    }
}

Javadoc comment

Starts with /**. The javadoc tool reads these comments and makes HTML documentation. Use them before classes and methods.

public class Doc {
    /**
     * Adds two numbers.
     *
     * @param a the first number
     * @param b the second number
     * @return the sum of a and b
     */
    static int add(int a, int b) {
        return a + b;
    }

    public static void main(String[] args) {
        System.out.println(add(2, 3));
    }
}

Comment out code

You can put // before a line to stop it from running, without deleting it. This is useful when you test.

public class Off {
    public static void main(String[] args) {
        System.out.println("One");
        // System.out.println("Two");
        System.out.println("Three");
    }
}

Good comments

• Explain why, not what. The code already shows what it does.
• Keep them short and update them when the code changes.
• Use clear names for variables and methods, then you need fewer comments.

• Previous Page
• Next Page

---

Exercises & Assignments
No Content Found.

Interview Questions & Answers
No Content Found.