dart-future-async-await

readme.md

dart-future-async-await

Created with <3 with dartpad.dev.

main.dart

void main() {
  performTasks();
  performTasksAsync();
}

void performTasks()  {
  String result = '';
  Future<String> f;
  result = task1();
  print (result);
  result = task2();
  print (result);
  f = task3();
  print (f);
  f.then((result) {
    print('Task 3 then: $result');
    task4().then((result) {
      print('Task 4 then: $result');
    });
  });
  f = task4();
  print(f);
  task5().catchError((e) {
    print('erro: $e');
    return '';
  });
}


void performTasksAsync() async {
  String result = '';
  result = task1();
  print (result);
  result = task2();
  print (result);
  result = await task3();
  print (result);
  result = await task4();
  print(result);
  try {
    await task5();
  } catch(e) {
    print('erro: $e');  
  }
  print('start task 3&4');
  await Future.wait([task3(), task4()]);
  print('task 3&4 completed');
    
}

String task1() {
  print('Task 1 complete');
  return "data1";
}

String task2()  {
  print('Task 2 complete');
  return 'data2';
}

Future<String> task3() async {
  print('Task 3 start');
  // Using a delay to simulate a future as would be returned by a http call
  return Future.delayed(const Duration(seconds:2), () {
    print('Task 3 complete');
    return 'data3';
  });
}

Future<String> task4() async {
  print('Task 4 start');
  // Using a delay to simulate a future as would be returned by a http call
  return Future.delayed(const Duration(seconds:1), () {
    print('Task 4 complete');
    return 'data4';
  });
}

Future<String> task5() async {
  print('Task 5 start');
  // Using a delay to simulate a future as would be returned by a http call
  throw Exception('Task 5 Error');
}