c# - 从 Task.Run 获取返回值

Question

我有以下代码:

public static async Task<string> Start(IProgress<ProcessTaskAsyncExProgress> progress)
{
    const int total = 10;
    for (var i = 0; i <= total; i++)
    {
        await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
        if (progress != null)
        {
            var args = new ProcessTaskAsyncExProgress
            {
                ProgressPercentage = (int)(i / (double)total * 100.0),
                Text = "processing " + i
            };
            progress.Report(args);
        }
    }
    return "Done";
}

private static string RunLongTask(string taskName)
{
    Task.Delay(300);
    return taskName + "Completed!";
}

如何从这一行取回 RunLongTask 的字符串值:await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));?

我试过:

var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture))).Result;

但我收到一条错误消息“字符串不可等待”。

Answer 1

从末尾删除 Result。当您await 时，您将从可等待的方法中获取Result。

var val = await Task.Run(() => RunLongTask(i.ToString(CultureInfo.InvariantCulture)));