从Future中返回值

本文介绍了从Future中返回值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我们可以从dart中的Future对象返回值还是从中获取值。通过阅读文档，我可以理解我们可以在Future类的then方法中传递一个函数，但是我仍然不知道如何返回该值。

Can we return or get the value from a Future object in dart. By reading the docs i could understand that we can pass a function in then method of Future class, but still i am clueless how can we return the value.

考虑如下伪代码

Int getTotalPay(){ Future<int> pension = getPensionFundAPI(); // a long running api call. don't wait here and call to next api int salary = getTotalSalary(); //wait here till we get the int value received in Future when the above api call completes. int result = salary + pension; print(result);

返回结果； }

return result; }

我知道我可以打电话给Future.then，然后在其中传递回调方法。但是我的目的是要在那时之外返回结果。

i know i can make call to Future.then and pass a callback method in there. but my purpose is to return the result outside of then. same as we do in java and other oops language.

在dart中可能吗？

推荐答案

不可能。就像无法将您80岁的自我带到现在和现在一样：）

It's not possible. Just like bringing your 80 year old self to here and now is not possible :)

但是，您可以编写看起来像可能的代码，但实际上运行着不同的部分在不同时间的单个功能。为此，您需要了解 async 和 await 关键字。

However, you can write code that looks like it's possible, but actually is running different parts of a single function in different times. For that, you need to learn about the async and await keywords.