async1.dart

import 'dart:math';

int randomSeconds() {
  var random = Random();
  return random.nextInt(10) + 1;
}

Future<String> callWebApi01() async {
  print('Start call to Web API 01...');
  final delay = randomSeconds();
  await Future.delayed(Duration(seconds: delay));
  return 'Data 1 returned in $delay seconds';
}

Future<String> callWebApi02() async {
  print('Start call to Web API 02...');
  final delay = randomSeconds();
  await Future.delayed(Duration(seconds: delay));
  return 'Data 2 returned in $delay seconds';
}

Stream<String> delayedTextStream() async* {
  for (int i = 1; i <= 5; i++) {
    await Future.delayed(Duration(seconds: randomSeconds()));
    yield 'Text $i';
  }
}

Stream<int> allEvenNumbers() async* {
  var num = 0;
  while (true) {
    num += 2;
    yield num;
  }
}

void main() async {
  // var data1 = await callWebApi01();
  // var data2 = await callWebApi02();
  //
  // var results = [data1, data2];
  // print(results);
  // var future1 = callWebApi01();
  // var future2 = callWebApi02();
  /*
  final results = await Future.wait([
    callWebApi01(),
    callWebApi02()
  ]);
  print(results);
  */
  /*
  final result = await Future.any([
    callWebApi01(),
    callWebApi02()
  ]);
  print(result);
  */
  /*
  Stream<String> st = delayedTextStream();

  st.listen((value) {
    print(value);
  });
  */

  await for (var data in delayedTextStream()) {
    print('Received $data');
  }
}