Comments are texts that are ignored by the compiler. They help you write information or explanation about your code. You can use comments to hide a part of your code.
We recommend you to use plenty of comments in your source code.
There are 3 types of comments in Java.
A single line comment begins with // and ends at the end of the line.
Everything you type after // is ignored by the compiler.
Here’s an example.
area = 2 * (width + breadth); // Calculate the area of the rectangle.
If you want, you can move the comment on a separate line.
// Calculate the area of the rectangle.
area = 2 * (width + breadth);
Here’s another example where the statement is broken onto two lines.
area = 2 * (width + breadth) // Calculate the area of the rectangle.
- 100; // Then subtract 100 from it.
A multi-line comment begins with /* and ends with */. It can span
over multiple lines.
Here’s an example.
/*
Calculate the area of the rectangle.
Then subtract 100 from it.
*/
area = 2 * (width + breadth) - 100;
Here’s another example.
/* Calculate the area of the rectangle.
Then subtract 100 from it. */
area = 2 * (width + breadth) - 100;
A multi-line comment can begin and end anywhere on a line.
Here’s an example where the comment is placed in the expression.
area = 2 * (width + breadth) /* Calculate the area of the rectangle.*/ - 100 /* Then subtract 100 from it. */;
Usually, multi-line comments appear on separate lines.
Multi-line comments cannot be nested. Here’s an example which results in error when you try to compile.
/*
This is a comment.
/* This is a nested comment. */
*/
A documentation comment begins with /** and ends with */. It can span
over multiple lines. It is similar to multi-line comments.