Future API

Another way to execute asynchronous operations is to use the Future API.

In the Future API, the then() method is used to register a callback, which fires upon the completion of Future.

These are two variants of using the Future API.

• Future<String>: Future returning String data type .
• Future<void>: Future returning void.

Future<String>

The example below transforms our earlier example code showcasing await and async into a Future API implementation. Lookout for the use of then() in the main() function. In this example, Future is returning a String.

By calling the asynchronous function makeDataCall() from main(), it will return a Future<String> and assign it to theFuture variable.