StringBuilder for performance in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new StringBuilder instance.

Kotlin

val sb = [1]()

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AString

BStringBuffer

CStringBuilder

DStringBuilderBuilder

Attempts:

3 left

💡 Hint

Common Mistakes

Using String instead of StringBuilder

Using a non-existent class like StringBuilderBuilder

Use StringBuilder() to create a new instance for efficient string concatenation.

2fill in blank

medium

Complete the code to append the word "Hello" to the StringBuilder.

Kotlin

sb.[1]("Hello")

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Aappend

Badd

Cinsert

Dconcat

Attempts:

3 left

💡 Hint

Common Mistakes

Using add which does not exist

Using concat which is for Strings, not StringBuilder

The append method adds text to the end of the StringBuilder.

3fill in blank

hard

Fix the error in the code to convert the StringBuilder content to a String.

Kotlin

val result = sb.[1]()

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AtoString

BasString

CtoStr

Dstringify

Attempts:

3 left

💡 Hint

Common Mistakes

Using toStr which does not exist

Using stringify which is not a Kotlin method

The correct method to get the string from StringBuilder is toString().

4fill in blank

hard

Fill both blanks to build a string with numbers 1 to 3 separated by commas.

Kotlin

val sb = StringBuilder()
for (i in 1..3) {
    sb.[1](i)
    if (i [2] 3) sb.append(", ")
}

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

Aappend

B<

C>

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using insert instead of append

Using > instead of < in the condition

Use append to add numbers and commas. The condition i < 3 avoids adding a comma after the last number.

5fill in blank

hard

Fill all three blanks to create a StringBuilder, append "Kotlin", and convert to String.

Kotlin

val [1] = [2]()
[1].append("Kotlin")
val result = [1].toString()

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

Abuilder

BStringBuilder

Csb

DStringBuffer

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'builder' as variable but not consistently

Using StringBuffer which is different

We name the variable sb, create a StringBuilder(), and use sb to append and convert to string.