Why coroutines simplify async programming in Android Kotlin - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to launch a coroutine in the main scope.

Android Kotlin

GlobalScope.[1] {
  println("Hello from coroutine")
}

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Aasync

BrunBlocking

Cdelay

Dlaunch

Attempts:

3 left

💡 Hint

Common Mistakes

Using runBlocking blocks the thread, which is not desired here.

Using delay is a suspending function, not a coroutine builder.

The launch function starts a new coroutine without blocking the current thread.

2fill in blank

medium

Complete the code to suspend a coroutine for 1 second.

Android Kotlin

suspend fun waitOneSecond() {
  [1](1000L)
}

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Await

BThread.sleep

Cdelay

Dsleep

Attempts:

3 left

💡 Hint

Common Mistakes

Using Thread.sleep blocks the thread, which defeats the purpose of coroutines.

The delay function suspends the coroutine without blocking the thread.

3fill in blank

hard

Fix the error in the coroutine builder to return a deferred result.

Android Kotlin

val deferred = GlobalScope.[1] {
  42
}

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Aasync

Bdelay

CrunBlocking

Dlaunch

Attempts:

3 left

💡 Hint

Common Mistakes

Using launch returns Job, not a result.

Using delay is not a builder.

The async builder returns a Deferred, which can hold a result.

4fill in blank

hard

Fill both blanks to create a coroutine scope and launch a coroutine.

Android Kotlin

val scope = CoroutineScope([1] + Job())
scope.[2] {
  println("Running in scope")
}

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ADispatchers.Main

Blaunch

CDispatchers.IO

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Using async when no result is needed.

Using Dispatchers.IO for UI work.

Use Dispatchers.Main for UI thread and launch to start coroutine.

5fill in blank

hard

Fill the two blanks to create a suspending function that fetches data asynchronously.

Android Kotlin

suspend fun fetchData(): String {
  return withContext([1]) {
    val data = apiCall()
    if (data.isNotEmpty()) data else [2]
  }
}

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ADispatchers.IO

Breturn

C"No data"

Dprintln

Attempts:

3 left

💡 Hint

Common Mistakes

Using Dispatchers.Main for network calls.

Using println instead of returning data.

withContext(Dispatchers.IO) switches to IO thread for network call.
The if expression returns the data or "No data" if empty.