Reified type parameters with inline in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an inline function with a reified type parameter.

Kotlin

inline fun <[1]> printTypeName() {
    println("Type: ${T::class.simpleName}")
}

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

AT

Binline T

Creified T

Dval T

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting the reified keyword causes a compilation error.

Using inline inside the angle brackets instead of before the function.

The reified keyword allows access to the type T at runtime inside an inline function.

2fill in blank

medium

Complete the code to check if an object is of type T using a reified type parameter.

Kotlin

inline fun <reified T> isType(value: Any): Boolean {
    return value is [1]
}

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AT

BAny

CUnit

DNothing

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use a non-reified type parameter in an is check causes an error.

Using a concrete type like Any instead of T.

Using value is T inside an inline function with a reified type parameter allows type checking at runtime.

3fill in blank

hard

Fix the error in the function to get the class name of type T using reified type parameters.

Kotlin

inline fun <reified T> getClassName(): String {
    return [1]::class.simpleName ?: "Unknown"
}

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AT.class

BT

CT::class

DT::class.java

Attempts:

3 left

💡 Hint

Common Mistakes

Using T.class which is Java syntax and invalid in Kotlin.

Using T::class.java which returns a Java class, not Kotlin class.

Inside an inline function with a reified type parameter, T::class is valid, but here the code uses T::class.simpleName. The blank expects T to use T::class.simpleName.

4fill in blank

hard

Fill both blanks to create a function that returns a list of elements filtered by type T using reified type parameters.

Kotlin

inline fun <reified T> filterByType(list: List<Any>): List<[1]> {
    return list.filterIsInstance<[2]>()
}

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AT

BAny

CString

DInt

Attempts:

3 left

💡 Hint

Common Mistakes

Using different types in the return type and filter function causes type mismatch.

Using concrete types like String or Int instead of the generic T.

The function uses the reified type parameter T to filter elements of that type from the list.

5fill in blank

hard

Fill all three blanks to create an inline function that casts a value to type T or returns null if the cast fails.

Kotlin

inline fun <reified T> safeCast(value: Any): [1]? {
    return value as? [2] ?: [3]
}

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AT

BAny

Cnull

DUnit

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-nullable return type causes compilation errors.

Returning Unit instead of null on cast failure.

The function returns the value cast to T or null if the cast fails, using the safe cast operator as?.