How to catch exception in an async method?-CodePudding

I am learning async and await. The following "catch" does not catch the exception thrown in DoTask. Assuming DoTask is a third party method that I can't change, how do I fix it so that the catch clause does catch the exception?

private static async Task DoTask()
{
    await Task.Delay(10000);
    throw new Exception("Exception!");
}


public static void Main(string[] args)
{
    try
    {
        Task.Run(async () => await DoTask());
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }

    Console.WriteLine("End");
    Console.ReadKey();
}

CodePudding user response：

How about this simplification:

public static async Task Main(string[] args)
{
    try
    {
        await DoTask();
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
    }

    Console.WriteLine("End");
    Console.ReadKey();
}

CodePudding user response：

Catching AggregateException will be possible if you use async/await - so the reason you don't catch it is not awaiting the Task.Run inside main - it just escapes the try clause immediately.

CodePudding user response：

I worked out - I need to wait for the task to finish. After I added the "Task.WaitAll(task);", it caught the exception.

private static async Task DoTask()
{
    await Task.Delay(10000);
    throw new Exception("Exception!");
}


public static void Main(string[] args)
{
    try
    {
        Task task = DoTask();
        Task.WaitAll(task);
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.InnerException.Message);
    }

    Console.WriteLine("End");
    Console.ReadKey();
}