Java Comments

Comments are lines of text in your code that are ignored by the compiler. They help you and others understand what the code does.

Single-line comments

Use two slashes // to comment out a single line:

java
// This is a comment

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

You can also put a comment at the end of a line:

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

Multi-line comments

Use / ... / to comment out several lines:

java
/*
  The code below prints a greeting.
  It is the first line shown to the user.
*/

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

Why use comments

• Explain tricky parts of the code.
• Remind yourself what a section does.
• Help other developers read your code.
• Temporarily disable a line while testing.

Comments are not executed

The compiler skips everything inside a comment, so comments never change how the program runs.

TL;DR

• // makes a single-line comment.
• / ... / makes a multi-line comment.
• Comments are ignored by the compiler.