Java Comments

In Java, comments are used to explain code and to generate documentation. It can also be used to prevent execution when testing alternative code.

Single-line Comments

In Java, single-line comments start with two forward slashes //.

Any text after the forward slashes // is ignored by Java (It will not be executed).

In the following example, we will use a single-line comment before a line of code:

// This line is a comment, and Java ignores it
System.out.println("Hello World!");

Output

Hello World!

In the following example, we will use a single-line comment at the end of a line of code:

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

Output

Hello World!

In Java, multi-line comments start with /* and end with */.

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

In the following example, we will use a multi-lice comment to explain the code:

/* This is the first line of a multi-comment
This is the second line. */
System.out.println("Hellow World!");

Note: Generally, we use // for short comments and /* */ for longer.