Future-async 심화학습 -2

어떤 순서로 함수가 출력될지 예상해보자.

void main() async{
  methodA();
  await methodB(); //methodB()의 실행이 끝날때까지 그 이하의 코드 실행이 멈춘다.
  await methodC('main');
  methodD();
}

methodA(){
  print('A'); 1 
}

methodB() async{
  print('B start'); 2
  await methodC('B'); // mathodC() 함수의 실행이 끝날때까지 그 이하의 코드 실행이 멈춘다.
  print('B end'); 5
}

methodC(String from) async{
  print('C start from $from'); 3 6
  
  Future((){
    print('C running Future from $from'); 9 11
  }).then((_){
    print('C end of Future from $from'); 10 12
  });
  
  print('C end from $from'); 4 7
}

methodD(){
  print('D'); 8
}

Console

A
B start
C start from B
C end from B
B end
C start from main
C end from main
D
C running Future from B
C end of Future from B
C running Future from main
C end of Future from main

ex2)

Future<void> futureTest() async{
  await Future.delayed(Duration(seconds: 3))
    .then((value){
    print('Here comes second');
    setState((){
      this.result = 'The data is fetched';
      print(result);
      print('Here comes third');
    });
    print('Here comes first');
    print('Here is the last one');
  }
}

Console

Here comes second
The data is fetched
Here comes third
Here comes first
Here is the last one

ex3)

void futureTest(){
  Future.delayed(Duration(seconds: 3))
    .then((value){
      setState((){
        this.result = 'The data is fetched';
        print(result);
      });
    });
    print('Here comes first');
  }
}

Console

Here comes first
The data is fetched