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Java Comments


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 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");

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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

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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");

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Single or multi-line comments?

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


Test Yourself With Exercises

Exercise:

Insert the missing part to create two types of comments.

 This is a single-line comment
 This is a multi-line comment 

Start the Exercise