Async/await and Futures in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an asynchronous function that returns a Future.

Flutter

Future<String> fetchData() async {
  [1] 'Data loaded';
}

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

Aasync

Breturn

Cyield

Dawait

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'await' instead of 'return' to send back the value.

Trying to use 'yield' which is for streams, not Futures.

The return keyword is used to send back the result from the async function wrapped in a Future.

2fill in blank

medium

Complete the code to wait for the Future result before printing it.

Flutter

void main() async {
  String data = await fetchData();
  print([1]);
}

Future<String> fetchData() async {
  return 'Hello';
}

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

Aawait data

BfetchData()

Cdata

Dmain()

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to print the function call instead of the variable.

Using 'await' inside print which is unnecessary here.

You print the variable data which holds the awaited result.

3fill in blank

hard

Fix the error in the code by completing the blank to correctly handle the Future.

Flutter

void main() {
  Future<String> future = fetchData();
  future.[1]((value) => print(value));
}

Future<String> fetchData() async {
  return 'Done';
}

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

AonComplete

Bawait

CcatchError

Dthen

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'await' outside an async function.

Using 'catchError' which handles errors, not success.

The then method is used to register a callback when the Future completes successfully.

4fill in blank

hard

Fill both blanks to create a Future that completes after 2 seconds and returns a message.

Flutter

Future<String> delayedMessage() {
  return Future.[1](Duration(seconds: 2), () => [2]);
}

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

Adelayed

B'Hello after delay'

Cprint('Hello')

Dimmediate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'immediate' which is not a Future method.

Trying to print inside the Future instead of returning a string.

Future.delayed creates a Future that completes after the given duration. The second argument is the value returned when it completes.

5fill in blank

hard

Fill all three blanks to create an async function that waits for two Futures and returns their combined result.

Flutter

Future<String> combinedData() async {
  String first = await fetchFirst();
  String second = await [1]();
  return first + [2] + [3];
}

Future<String> fetchFirst() async => 'Hello';
Future<String> fetchSecond() async => 'World';

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

AfetchSecond

B' '

Csecond

DfetchFirst

Attempts:

3 left

💡 Hint

Common Mistakes

Calling fetchFirst() again instead of fetchSecond().

Forgetting to add a space between the words.

Returning variables that are not defined.

The function waits for fetchSecond(), then returns the concatenation of first, a space, and second.