Java Comments

Comments can be used to explain Java code, and to make it more readable. It can also be used to prevent execution when testing alternative code.

Single-line Comments

Single-line comments start with two forward slashes (//).

Any text between // and the end of the line is ignored by Java (will not be executed).

This example uses a single-line comment before a line of code:

Example

// This is a comment

System.out.println("Hello World");

This example uses a single-line comment at the end of a line of code:

Example

System.out.println("Hello World"); // This is a comment

Java Multi-line Comments

Multi-line comments start with /* and ends with */.

Any text between /* and */ will be ignored by Java.

This example uses a multi-line comment (a comment block) to explain the code:

Example

/* The code below will print the words Hello World

to the screen, and it is amazing */

System.out.println("Hello World");

Single or multi-line comments?

It is up to you which you want to use. Normally, we use // for short comments, and /* */ for longer.