Code Ronna

Here are three ways to comment out code in Kotlin and an example code.

1. Single line comment

You can write a single comment by using double slash (//) .

Used to write single-line comments. 

Example code 1 : 

/// This line is comment outed

/// This line is also comment outed

Example code 2 : 

/// Define variable fizz
val fizz = 1234

/// Add 100 to fizz
fizz += 100

2. Multiple lines comment

You can write multiple lines comment by using /*…*/ syntax.

Example code 1 : 

/**
 * Those lines are comment outed.
 **/

Example code 2 : 

/*
* /// Comment out codes
* var fizz = 123
* fizz += 456
*/

It is useful for commenting out multiple lines of code and annotating methods, classes, variables, processes, etc.

3. Python style comment

In fact, you can also use Python-like commenting out in Kotlin.

It’s a multi-line comment with a string literal.

See the some sample codes below…

Example code 1 :

/// Comment by string literal

"""
This line is comment outed.
This line is also comment outed.
"""

Example code 2 :

/// Comment out multiple codes

"""
var fizz = 123
fizz += 456
"""

For normal comment-out, the aforementioned comment-out methods are sufficient. There are usually no situations where Python-style comment-out is needed.

How python style comment is used?

However, if you include /* or */ in your code, you cannot comment out multiple lines. For example, the following code contains a MIME type

Example code (Not works) :

/*
var mimeType = "*/*"
            //  ^ Not correct!!
 
System.out.println("MIME type is...")
if(mimeType.startsWidth("image")){
    System.out.println("Image")
}else{
    System.out.println("Not image")
}
*/

As you can see from the highlight above, */* is interpreted as the end of the comment.

Python-style comments are useful in these cases.

Example code (Works) :

/// Fixed to python style comment
"""
var mimeType = "*/*" 
             // ^ Works correctly!! 

System.out.println("MIME type is...") 
if(mimeType.startsWidth("image")){ 
    System.out.println("Image") 
}else{ 
    System.out.println("Not image") 
}
"""

Works correctly.