Async and await for concurrent results in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start an asynchronous task using Kotlin coroutines.

Kotlin

val deferred = scope.[1] {
    delay(1000L)
    "Hello"
}

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AwithContext

Blaunch

CrunBlocking

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch instead of async, which does not return a Deferred result.

Using runBlocking inside a coroutine scope incorrectly.

The async builder starts a coroutine that returns a Deferred result, which can be awaited later.

2fill in blank

medium

Complete the code to wait for the result of an asynchronous task.

Kotlin

val result = deferred.[1]()

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Aawait

Bcancel

Cjoin

Dstart

Attempts:

3 left

💡 Hint

Common Mistakes

Using join() instead of await(), which does not return the result.

Trying to call start() which is not a function on Deferred.

The await() function suspends until the asynchronous task completes and returns its result.

3fill in blank

hard

Fix the error in the code to run two async tasks concurrently and get their results.

Kotlin

val deferred1 = scope.async { fetchData1() }
val deferred2 = scope.async { fetchData2() }
val result1 = deferred1.[1]()
val result2 = deferred2.[1]()

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Ajoin

Bawait

Cstart

Dcancel

Attempts:

3 left

💡 Hint

Common Mistakes

Using join() instead of await(), causing no result to be returned.

Calling start() which is not a method on Deferred.

Both deferred1 and deferred2 need to be awaited to get their results concurrently.

4fill in blank

hard

Fill both blanks to create a map of word lengths for words longer than 3 characters.

Kotlin

val words = listOf("apple", "bat", "carrot", "dog")
val lengths = words.filter { it.length [1] 3 }.associateWith { it.[2] }

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A>

Blength

C<

Dcount

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' causing wrong filtering.

Using count() instead of length property.

Filter words with length greater than 3, then map each word to its length property.

5fill in blank

hard

Fill all three blanks to create a map of uppercase keys to values greater than zero.

Kotlin

val data = mapOf("a" to 1, "b" to 0, "c" to 3)
val result = data.filter { it.value [1] 0 }.mapKeys { it.key.[2]() }.mapValues { it.[3] }

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A<

Bvalue

C>

Duppercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in filter condition.

Using key instead of value in mapValues.

Filter entries with values greater than zero, convert keys to uppercase, and keep the values.