Programming Flutter

Asynchronous Code in Dart: The dart:async Library

At some point during your Dart development process, you might need to call a method without affecting the execution of your code, or call a library method that has been declared as an async method.

That’s when you realize the necessity for asynchronous code and the dart:async built-in Dart library, which allows async functions to return either a Future or a Stream.

The Future

The Future is the most basic object type related to asynchronous methods—it is the return type of all async functions, including void ones:

Future<void> doSomethingThatTakesLong() async {
  // do something
}

void callingSyncFunction() {
  doSomethingThatTakesLong();
  /* the code won't wait for the function to ...