RunBlocking for bridging in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to start a coroutine that blocks the current thread until it completes.

Kotlin

import kotlinx.coroutines.*

fun main() {
    [1] {
        println("Hello from coroutine!")
    }
}

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Alaunch

Basync

CrunBlocking

Ddelay

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch which is non-blocking and returns immediately.

Using async without awaiting the result.

runBlocking starts a coroutine and blocks the current thread until it finishes. This is useful for bridging regular blocking code with coroutines.

2fill in blank

medium

Complete the code to delay inside a runBlocking coroutine.

Kotlin

import kotlinx.coroutines.*

fun main() = [1] {
    println("Start")
    delay(500)
    println("End")
}

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ArunBlocking

Basync

Claunch

DwithContext

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch which does not block the main thread.

Trying to call delay outside a coroutine scope.

runBlocking is used here to create a coroutine scope that blocks the main thread, allowing delay to suspend inside it.

3fill in blank

hard

Fix the error in the code by choosing the correct coroutine builder to bridge blocking and suspending code.

Kotlin

import kotlinx.coroutines.*

fun main() {
    [1] {
        val result = async {
            delay(100)
            "Done"
        }.await()
        println(result)
    }
}

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Alaunch

BrunBlocking

CGlobalScope.launch

DcoroutineScope

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch which returns immediately and does not block.

Using GlobalScope.launch which is also non-blocking.

runBlocking is needed here to block the main thread until the coroutine completes and the result is printed.

4fill in blank

hard

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

Kotlin

import kotlinx.coroutines.*

fun main() = [1] {
    val words = listOf("apple", "bat", "carrot", "dog")
    val lengths = words.filter { word -> word.length > 3 }.associate { word -> word to [2] }
    println(lengths)
}

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ArunBlocking

Bword.length

Cword.uppercase()

Dlaunch

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch which does not block the main thread.

Using word.uppercase() instead of length.

runBlocking creates the coroutine scope that blocks the main thread. The map comprehension uses word.length to get the length of each word.

5fill in blank

hard

Fill all three blanks to create a filtered map of uppercase words and their lengths inside runBlocking.

Kotlin

import kotlinx.coroutines.*

fun main() = [1] {
    val words = listOf("apple", "bat", "carrot", "dog")
    val filtered = words.filter { word -> word.length > 3 }.associate { word -> word.[2]() to word.[3] }
    println(filtered)
}

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ArunBlocking

Buppercase

Clength

Dlowercase

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase instead of uppercase.

Using launch instead of runBlocking.

runBlocking blocks the main thread. word.uppercase() converts words to uppercase keys, and length gets their lengths as values.