如何在控制台应用程序中从Task.WaitAll（）获取返回值？

I am using a console app as a proof of concept and new need to get an async return value.

我使用控制台应用程序作为概念证明和获得异步返回值的新需求。

I figured out that I need to use Task.WaitAll() in my main method to avoid needing an async "main()" method, which is illegal.

我发现我需要在main方法中使用Task.WaitAll（）来避免需要异步“main（）”方法，这是非法的。

I'm now stuck trying to figure out an overload that allows me to use generics or just returns an object that I can cast, but while in Main().

我现在卡住试图弄清楚允许我使用泛型的重载，或者只返回我可以强制转换的对象，但是在Main（）中。

2 个解决方案

#1

You don't get a return value from Task.WaitAll. You only use it to wait for completion of multiple tasks and then get the return value from the tasks themselves.

您没有从Task.WaitAll获得返回值。您只能使用它等待多个任务的完成，然后从任务本身获取返回值。

var task1 = GetAsync(1);
var task2 = GetAsync(2);
Task.WaitAll(task1, task2);
var result1 = task1.Result;
var result2 = task2.Result;

If you only have a single Task, just use the Result property. It will return your value and block the calling thread if the task hasn't finished yet:

如果您只有一个Task，只需使用Result属性。如果任务尚未完成，它将返回您的值并阻止调用线程：

var task = GetAsync(3);
var result = task.Result;

It's generally not a good idea to synchronously wait (block) on an asynchronous task ("sync over async"), but I guess that's fine for a POC.

在异步任务上同步等待（阻塞）通常不是一个好主意（“异步同步”），但我猜这对于POC来说很好。

#2

For best practice, use the new async way of doing things. Instead of

为了获得最佳实践，请使用新的异步处理方式。代替

Task.WaitAll use await Task.WhenAll
Task.WaitAll使用await Task.WhenAll
Task.WaitAny use await Task.WhenAny
Task.WaitAny使用await Task.WhenAny

The code above can be written as:

上面的代码可以写成：

var task1 = GetAsync(1);
var task2 = GetAsync(2);
var results = await Task.WhenAll(task1, task2);
var result1 = results[0];
var result2 = results[1];

#1