Coroutines for async networking in Android Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

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

Android Kotlin

GlobalScope.launch(Dispatchers.[1]) {
    // network call here
}

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ADefault

BIO

CUnconfined

DMain

Attempts:

3 left

💡 Hint

Common Mistakes

Using Dispatchers.IO for UI work causes errors.

Forgetting to specify a dispatcher.

Use Dispatchers.Main to run coroutines on the main thread, suitable for UI updates.

2fill in blank

medium

Complete the code to make a network call asynchronously using suspend function.

Android Kotlin

suspend fun fetchData() : String {
    return withContext(Dispatchers.[1]) {
        // simulate network call
        "data"
    }
}

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AMain

BIO

CDefault

DUnconfined

Attempts:

3 left

💡 Hint

Common Mistakes

Using Dispatchers.Main causes app to freeze.

Using Dispatchers.Default is less efficient for IO.

Use Dispatchers.IO for blocking IO tasks like network calls to avoid blocking the main thread.

3fill in blank

hard

Fix the error in the coroutine builder to properly handle exceptions.

Android Kotlin

GlobalScope.launch(Dispatchers.IO) {
    try {
        val result = fetchData()
        withContext(Dispatchers.[1]) {
            // update UI with result
        }
    } catch (e: Exception) {
        // handle error
    }
}

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AMain

BIO

CDefault

DUnconfined

Attempts:

3 left

💡 Hint

Common Mistakes

Updating UI on Dispatchers.IO causes crashes.

Not catching exceptions in coroutines.

UI updates must happen on the main thread, so use Dispatchers.Main inside withContext.

4fill in blank

hard

Fill both blanks to create a coroutine scope and launch a coroutine for network call.

Android Kotlin

val scope = CoroutineScope(Dispatchers.[1] + Job())
scope.[2] {
    val data = fetchData()
    // process data
}

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AIO

Blaunch

CMain

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Using async when no result is needed.

Using Main dispatcher for network calls.

Use Dispatchers.IO for network calls and launch to start a coroutine without returning a result.

5fill in blank

hard

Fill all three blanks to create an async coroutine that fetches data and awaits the result.

Android Kotlin

val deferred = CoroutineScope(Dispatchers.[1]).[2] {
    fetchData()
}
val result = deferred.[3]()

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

AMain

BIO

Cawait

Dasync

Attempts:

3 left

💡 Hint

Common Mistakes

Calling await() on a non-Deferred object.

Using Main dispatcher for network calls.

Use Dispatchers.IO for network, async to start coroutine returning Deferred, and await to get result.