Comments and documentation syntax in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to write a single-line comment in Kotlin.

Kotlin

//[1] This is a comment

Drag options to blanks, or click blank then click option'

A This is a single-line

B This is a

C This is

D This is a single-line comment

Attempts:

3 left

💡 Hint

Common Mistakes

Using /* */ for single-line comments

Forgetting the slashes at the start

In Kotlin, single-line comments start with //. Anything after // on the same line is a comment.

2fill in blank

medium

Complete the code to write a multi-line comment in Kotlin.

Kotlin

/*[1]
This is a multi-line comment
*/

Drag options to blanks, or click blank then click option'

A This is a multi-line comment

B This is a multi-line comment start

C This is a multi-line comment block

D This is a multi-line comment example

Attempts:

3 left

💡 Hint

Common Mistakes

Using // for multi-line comments

Not closing the comment with */

Multi-line comments in Kotlin start with /* and end with */. Everything in between is part of the comment.

3fill in blank

hard

Fix the error in the Kotlin documentation comment syntax.

Kotlin

/**[1]
 * This function adds two numbers.
 */

Drag options to blanks, or click blank then click option'

A This is a single-line comment

B This is a normal comment

C This is a multi-line comment

D This is a documentation comment

Attempts:

3 left

💡 Hint

Common Mistakes

Using /* instead of /** for documentation comments

Confusing documentation comments with normal comments

Kotlin documentation comments start with /** and are used to describe code elements. They are different from normal comments.

4fill in blank

hard

Fill both blanks to create a Kotlin documentation comment for a function.

Kotlin

/**
 * [1] adds two integers.
 * @param [2] first number
 */

Drag options to blanks, or click blank then click option'

AThis function

Bnum1

Cnumber1

DAdds

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter names in @param

Not describing the function clearly

Documentation comments describe the function and its parameters. Use @param to explain each parameter.

5fill in blank

hard

Fill all three blanks to complete the Kotlin documentation comment with description, parameter, and return tag.

Kotlin

/**
 * [1] multiplies two numbers.
 * @param [2] first number
 * @return [3] the product
 */

Drag options to blanks, or click blank then click option'

AThis function

BnumA

Cthe result

DnumB

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing parameter names

Forgetting the @return tag

Documentation comments should describe the function, its parameters, and what it returns using @param and @return tags.

Practice

1. Which of the following is the correct way to write a single-line comment in Kotlin?

easy

A. /* This is a single-line comment */

B.

C. // This is a single-line comment

D. # This is a single-line comment

Solution

1. Step 1: Identify single-line comment syntax in Kotlin

   Kotlin uses // to start a single-line comment.

2. Step 2: Compare options

   // This is a single-line comment uses //, which is correct. /* This is a single-line comment */ is for multi-line comments. <!-- This is a single-line comment --> is HTML style. # This is a single-line comment is used in some scripting languages but not Kotlin.

3. Final Answer:

   // This is a single-line comment -> Option C

4. Quick Check:

   Single-line comment = // [OK]

Hint: Single-line comments start with // in Kotlin [OK]

Common Mistakes:

• Using /* */ for single-line comments
• Using # or which are not Kotlin comments
• Confusing multi-line and single-line comment syntax

2. Which of the following is the correct syntax for a multi-line comment in Kotlin?

easy

A. /* This is a multi-line comment */

B.

C. /** This is a multi-line comment */

D. // This is a multi-line comment

Solution

1. Step 1: Recall multi-line comment syntax in Kotlin

   Kotlin uses /* ... */ to write multi-line comments.

2. Step 2: Analyze options

   /* This is a multi-line comment */ correctly uses /* ... */. // This is a multi-line comment is single-line comment syntax. /** This is a multi-line comment */ is documentation comment syntax. <!-- This is a multi-line comment --> is HTML comment syntax.

3. Final Answer:

   /* This is a multi-line comment */ -> Option A

4. Quick Check:

   Multi-line comment = /* ... */ [OK]

Hint: Multi-line comments use /* and */ to start and end [OK]

Common Mistakes:

• Using // for multi-line comments
• Confusing documentation comments /** */ with regular multi-line comments
• Using HTML style comments

3. What will be the output of the following Kotlin code?

fun main() {
    // println("Hello")
    println("World")
}

medium

A. Hello
World

B. World

C. Hello

D. No output

Solution

1. Step 1: Understand comment effect on code execution

   The line // println("Hello") is a comment, so it does not run.

2. Step 2: Identify which println runs

   Only println("World") runs, so output is "World".

3. Final Answer:

   World -> Option B

4. Quick Check:

   Commented code does not run = World [OK]

Hint: Commented lines do not execute, only uncommented print runs [OK]

Common Mistakes:

• Thinking commented println runs
• Expecting both lines to print
• Confusing comment syntax and output

4. Identify the error in the following Kotlin code snippet:

fun main() {
    /* This is a comment
    println("Hello")
}

medium

A. No error, code runs fine

B. Incorrect single-line comment syntax

C. Missing quotation marks in println

D. Missing closing */ for multi-line comment

Solution

1. Step 1: Check multi-line comment syntax

   The comment starts with /* but does not have a closing */.

2. Step 2: Understand impact of missing closing comment

   Without closing */, the compiler treats the rest as comment, causing syntax error.

3. Final Answer:

   Missing closing */ for multi-line comment -> Option D

4. Quick Check:

   Multi-line comments must close with */ [OK]

Hint: Always close multi-line comments with */ [OK]

Common Mistakes:

• Forgetting to close multi-line comments
• Confusing single-line and multi-line comment syntax
• Assuming code inside unclosed comment runs

5. Which comment style should you use in Kotlin to write documentation that tools can extract to generate API docs?

hard

A. /** This is a documentation comment */

B. /* This is a documentation comment */

C. // This is a documentation comment

D.

Solution

1. Step 1: Identify documentation comment syntax in Kotlin

   Kotlin uses /** ... */ for documentation comments that tools can parse.

2. Step 2: Compare with other comment types

   // This is a documentation comment is single-line comment syntax. /* This is a documentation comment */ is regular multi-line comment syntax. <!-- This is a documentation comment --> is HTML comment syntax.

3. Final Answer:

   /** This is a documentation comment */ -> Option A

4. Quick Check:

   Documentation comments use /** ... */ [OK]

Hint: Use /** ... */ for documentation comments in Kotlin [OK]

Common Mistakes:

• Using // or /* */ for documentation comments
• Confusing documentation comments with regular comments
• Using HTML comment style by mistake