如何在 Dart 中的 List.forEach() 中异步/等待 [英] How to Async/await in List.forEach() in Dart

问题描述

我正在编写某种机器人(命令行应用程序)，但在使用forEach"时遇到异步执行问题.方法.这是我正在尝试做的简化代码:

I'm writing some kind of bot (command line application) and I'm having trouble with async execution when I'm using the "forEach" method. Here is a simplified code of what I'm trying to do :

main() async {
  print("main start");
  await asyncOne();
  print("main end");
}

asyncOne() async {
  print("asyncOne start");
  [1, 2, 3].forEach(await (num) async {
    await asyncTwo(num);
  });
  print("asyncOne end");
}

asyncTwo(num) async
{
  print("asyncTwo #${num}");
}

这是输出:

main start
asyncOne start
asyncOne end
main end
asyncTwo #1
asyncTwo #2
asyncTwo #3

我想要的是:

main start
asyncOne start
asyncTwo #1
asyncTwo #2
asyncTwo #3
asyncOne end
main end

如果有人知道我做错了什么，我将不胜感激.

If someone knows what I'm doing wrong I would appreciate it.

推荐答案

我认为使用 forEach 方法无法实现您想要的效果.但是，它将与 for 循环一起使用.例子;

I don't think it's possible to achieve what you want with the forEach method. However it will work with a for loop. Example;

asyncOne() async {
  print("asyncOne start");
  for (num number in [1, 2, 3])
    await asyncTwo(number);
  print("asyncOne end");
}

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