Multiple type parameters in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a generic class with two type parameters.

Kotlin

class Pair<[1], B>(val first: [1], val second: B)

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AK

BA

CX

DT

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase letters for type parameters.

Using non-letter characters.

The first type parameter is commonly named T, so we use T for the first generic type.

2fill in blank

medium

Complete the function signature to use two generic type parameters.

Kotlin

fun <[1], [2]> createPair(first: [1], second: [2]): Pair<[1], [2]> = Pair(first, second)

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AT

BU

CV

DW

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same type parameter twice.

Not declaring generic parameters before the function name.

We use T and U as the two generic type parameters consistently in the function signature.

3fill in blank

hard

Fix the error in the generic class declaration with two type parameters.

Kotlin

class Box<[1], [2]>(val content1: [1], val content2: [2])

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AT

BT, U

CT U

DU

Attempts:

3 left

💡 Hint

Common Mistakes

Separating type parameters with spaces or semicolons.

Using only one type parameter when two are needed.

Type parameters must be separated by commas inside angle brackets. So use T and U separated by a comma.

4fill in blank

hard

Fill both blanks to create a generic function that swaps two values of different types.

Kotlin

fun <[1], [2]> swap(pair: Pair<[1], [2]>): Pair<[2], [1]> = Pair(pair.second, pair.first)

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AT

BU

CV

DW

Attempts:

3 left

💡 Hint

Common Mistakes

Using the same type parameter for both elements.

Not swapping the type parameters in the return type.

We use T and U as the two generic type parameters consistently to swap the pair elements.

5fill in blank

hard

Fill all three blanks to define a generic class with three type parameters and a method returning a Triple.

Kotlin

class TripleHolder<[1], [2], [3]>(val first: [1], val second: [2], val third: [3]) {
    fun toTriple(): Triple<[1], [2], [3]> = Triple(first, second, third)
}

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AA

BB

CC

DD

Attempts:

3 left

💡 Hint

Common Mistakes

Using fewer than three type parameters.

Not matching the type parameters in the method return type.

We use A, B, and C as the three generic type parameters consistently in the class and method.