Learn how to write a multi-line comment in Java using /* */. This program uses a multi-line comment to explain the code, declares an integer variable and prints its value. It also shows a comment placed inside a line of code. The compiler ignores all comments, so they don't change the output.
/* and *//* */ comment inside a line of codemain() methodSystem.out.println()int data type//MultiLineComment.main() method.number and assign it 10.number.total = number + 5, with an inline /* */ comment inside the expression.total.Environment: JDK (Windows, Linux, macOS)
Execution command:
javac MultiLineComment.java
java MultiLineCommentpublic class MultiLineComment {
public static void main(String[] args) {
/* This is a multi-line comment.
In this program, we are going to
declare a variable and print its value in Java. */
int number = 10;
System.out.println(number);
/*
* A multi-line comment can also be written
* with a * at the start of each line.
* This style is easier to read.
*/
int total = number /* inline comment */ + 5;
System.out.println(total);
}
}No input required
10
15
A multi-line comment (also called a block comment) starts with /* and ends with */.
The compiler ignores everything between these two markers, however many lines it covers.
It's useful for longer explanations that don't fit comfortably on one line.
*/ the compiler finds. That's why you can't put one multi-line comment inside another.
Text spread across several lines.
/* This is a multi-line comment.
In this program, we are going to
declare a variable and print its value in Java. */
The comment opens with /* on the first line and closes with */ on the last line. All three lines are ignored.
The code that actually runs.
int number = 10;
System.out.println(number);
This creates an integer variable number with the value 10 and prints it.
The most common professional style.
/*
* A multi-line comment can also be written
* with a * at the start of each line.
* This style is easier to read.
*/
The * at the start of each middle line is optional. Java treats it as part of the comment text, but it makes the comment block easier to see.
A comment inside a statement.
int total = number /* inline comment */ + 5;
System.out.println(total);
Because /* */ has a clear end marker, it can sit in the middle of a line. The compiler reads this as number + 5, so 15 is printed.
A // comment can't do this, because it hides everything to the end of the line.
| Feature | Single-Line // |
Multi-Line /* */ |
|---|---|---|
| Ends at | End of the line | The closing */ |
| Covers several lines | No, needs // on each line |
Yes |
| Can sit inside a statement | No | Yes |
| Best for | Short notes | Longer explanations, or switching off a block of code |
10
15/* outer /* inner */ outer */, the first */ ends the comment. The leftover outer */ causes a compile error.
*/, the rest of the file becomes a comment and you get an unclosed comment error.
/ * or * / isn't a comment marker. There must be no space between / and *.
/* */ to switch it off while testing. Make sure that block has no */ inside it.
A multi-line comment starts with /* and ends with */. It can cover many lines or sit inside a statement, but it can't be nested. The compiler ignores it, so the output stays the same.
Time: O(1)
Space: O(1)
First understand the algorithm carefully. Then study the program line-by-line and compare it with the output. Finally, review the explanation section to strengthen your logic and programming understanding.
Rewrite the program without looking at the code. Modify values, conditions or logic and run it again. This helps improve confidence and strengthens coding skills much faster.
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