Flutter for Beginners

Dart Futures

The Future<T> object in Dart represents a value that will be provided sometime in the future. It can be used to mark a method, for example, with a future result; that is, a method returning a Future<T> object will not have the proper result value immediately, but instead after some computation at a later point in time.

Consider the following code, where we have the main function that calls a long-running operation:

import 'dart:io';void longRunningOperation() {  for (int i = 0; i < 5; i++) {    sleep(Duration(seconds: 1));    print("index: $i");  }}main() {  print("start of long running operation");  longRunningOperation();  print("continuing main body");  for (int i = 10; i < 15; i++) {     sleep(Duration(seconds: 1)); print("index from main: ...