Multiline strings with trimIndent in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a multiline string in Kotlin?

A multiline string in Kotlin is a string enclosed in triple quotes ("""), allowing the string to span multiple lines without needing escape characters.

beginner

What does the trimIndent() function do when used with multiline strings?

trimIndent() removes the common minimal indent from all lines in a multiline string, making the string's content aligned to the left without extra spaces.

intermediate

How does trimIndent() help with code readability?

It allows you to indent multiline strings in your code to match the surrounding code style, but still outputs the string without those indents, keeping the string clean.

beginner

Given this Kotlin code:

val text = """
    Hello
    World
""".trimIndent()

What will be the output of println(text)?

The output will be:

Hello
World

The trimIndent() removes the 4 spaces before each line.

intermediate

Can trimIndent() remove different amounts of spaces on each line?

No, trimIndent() removes the smallest common indent from all lines. Lines with less indent are not changed, and lines with more indent lose only the common part.

What symbol is used to start and end a multiline string in Kotlin?

A `

B "

C """

D '

Multiline strings in Kotlin are enclosed in triple double quotes: """.

What does trimIndent() do to a multiline string?

A Adds indentation to all lines

B Converts the string to uppercase

C Removes all spaces from the string

D Removes the smallest common indent from all lines

trimIndent() removes the smallest common indent from all lines in the string.

If a multiline string has lines with different indents, how does trimIndent() behave?

A Removes all indentation from every line

B Removes the smallest common indent from all lines

C Removes indentation only from the first line

D Leaves the string unchanged

trimIndent() removes only the smallest common indent shared by all lines.

Why is trimIndent() useful when writing multiline strings in code?

A It lets you indent strings in code for readability without affecting the actual string content

B It encrypts the string content

C It converts the string to a list

D It adds line numbers to the string

trimIndent() helps keep code readable by allowing indentation without adding spaces to the string.

What will this code print?

val s = """
  Kotlin
    Rocks
""".trimIndent()
println(s)

A Kotlin Rocks

B Kotlin Rocks

C Kotlin Rocks

D skcoR niltoK

The smallest common indent is 2 spaces, so those are removed from each line. The second line keeps its extra 2 spaces.

Explain how trimIndent() works with multiline strings in Kotlin and why it is helpful.

Think about how indentation in code can affect string output.

Describe a situation where using a multiline string with trimIndent() would be better than a regular string.

Consider writing a message or template inside code.

Practice

1. What does the trimIndent() function do when used with multiline strings in Kotlin?

easy

A. It converts the string to uppercase.

B. It adds extra spaces at the beginning of each line.

C. It splits the string into a list of lines.

D. It removes the common leading whitespace from each line.

Solution

1. Step 1: Understand the purpose of trimIndent()

   The function trimIndent() removes the common leading whitespace from every line in a multiline string.

2. Step 2: Effect on multiline strings

   This makes the string output aligned neatly without extra indentation caused by code formatting.

3. Final Answer:

   It removes the common leading whitespace from each line. -> Option D

4. Quick Check:

   trimIndent() = removes leading spaces [OK]

Hint: trimIndent() cleans leading spaces for neat multiline strings [OK]

Common Mistakes:

• Thinking trimIndent() adds spaces instead of removing
• Confusing trimIndent() with uppercase conversion
• Assuming trimIndent() splits strings into lines

2. Which of the following is the correct syntax to create a multiline string with trimmed indentation in Kotlin?

easy

A. val text = """Hello\nWorld""".trimIndent()

B. val text = "Hello\nWorld".trimIndent()

C. val text = '''Hello\nWorld'''.trimIndent()

D. val text = ""Hello\nWorld"".trimIndent()

Solution

1. Step 1: Identify multiline string syntax

   Kotlin uses triple double quotes """ to create multiline strings.

2. Step 2: Apply trimIndent() correctly

   Calling trimIndent() on the multiline string removes common leading spaces.

3. Final Answer:

   val text = """Hello\nWorld""".trimIndent() -> Option A

4. Quick Check:

   Triple quotes + trimIndent() = correct syntax [OK]

Hint: Use triple quotes """ for multiline strings with trimIndent() [OK]

Common Mistakes:

• Using single quotes instead of triple quotes
• Trying to trimIndent() on a normal string
• Wrong quote count causing syntax errors

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

val text = """
    Kotlin
    is
    fun
""".trimIndent()
println(text)

medium

A. Kotlin
is
fun

B. Kotlin
is
fun

C. Kotlin
is
fun

D. Kotlin is fun

Solution

1. Step 1: Analyze the multiline string with indentation

   The string has 4 spaces before each line inside the triple quotes.

2. Step 2: Effect of trimIndent()

   trimIndent() removes the common 4-space indentation from all lines.

3. Final Answer:

   Kotlin is fun -> Option C

4. Quick Check:

   trimIndent() removes leading spaces = clean lines [OK]

Hint: trimIndent() removes common leading spaces from all lines [OK]

Common Mistakes:

• Expecting original indentation to remain
• Confusing trimIndent() with trim() which removes only ends
• Thinking output is a single line string

4. Identify the error in this Kotlin code snippet using multiline strings and trimIndent():

val message = """
  Hello
    World
"".trimIndent()
println(message)

medium

A. Missing one double quote in the closing triple quotes.

B. The closing triple quotes should be """ not "".

C. No error; code runs and prints correctly.

D. Incorrect use of trimIndent() on a non-multiline string.

Solution

1. Step 1: Check triple quote syntax

   Multiline strings require triple double quotes """ at start and end.

2. Step 2: Identify the closing quotes

   The code uses only two double quotes "" at the end, which is invalid syntax.

3. Step 3: Correct the closing quotes

   It should be """ to properly close the multiline string.

4. Final Answer:

   The closing triple quotes should be """ not "". -> Option B

5. Quick Check:

   Triple quotes must match at start and end [OK]

Hint: Always close multiline strings with triple quotes """ [OK]

Common Mistakes:

• Using two quotes instead of three to close multiline strings
• Assuming trimIndent() fixes quote errors
• Confusing trimIndent() with trimming quotes

5. You want to create a multiline string in Kotlin that shows a list of fruits without extra indentation in the output. Which code snippet correctly achieves this using trimIndent()?

hard

A. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

B. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

C. val fruits = """
- Apple
- Banana
- Cherry
""".trimIndent()
println(fruits)

D. val fruits = "- Apple\n- Banana\n- Cherry".trimIndent()
println(fruits)

Solution

1. Step 1: Understand trimIndent() effect on indentation

   trimIndent() removes the common leading spaces from all lines, aligning text properly.

2. Step 2: Check each option's indentation

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has consistent 4-space indentation on each line, so trimIndent() will remove it neatly.

3. Step 3: Evaluate other options

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has uneven indentation, so trimIndent() removes nothing and leaves extra spaces on some lines. val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) has uneven indentation, so trimIndent() won't align all lines properly. val fruits = "- Apple\n- Banana\n- Cherry".trimIndent() println(fruits) is a normal string, trimIndent() has no effect.

4. Final Answer:

   val fruits = """ - Apple - Banana - Cherry """.trimIndent() println(fruits) -> Option A

5. Quick Check:

   Consistent indentation + trimIndent() = neat output [OK]

Hint: Use consistent indentation inside triple quotes before trimIndent() [OK]

Common Mistakes:

• Using uneven indentation causing partial trimming
• Not using triple quotes for multiline strings
• Expecting trimIndent() to fix uneven spaces