Completing Futures

Using a Future with then, catchError, async, and await is probably enough for most use cases, but there is another way to deal with asynchronous programming in Dart and Flutter: the Completer class.

Completer creates Future objects that you can complete later with a value or an error. We will be using Completer in this recipe.

Getting ready

In order to follow along with this recipe, there are the following requirements:

• You can modify the project completed in the previous recipes in this chapter.
• OR, you can create a new project from the starting code available at https://github.com/PacktPublishing/Flutter-Cookbook/tree/master/chapter_07.

How to do it...

In this recipe, you will see how to use the Completer class to perform a long-running task:

• Add the following code in the main.dart file, in the _FuturePageState class:

late Completer completer;
Future getNumber() {
    completer = Completer<int>();
    calculate();
    return completer.future;
  }
calculate...