Task.Factory.StartNew <TResult> （功能 <Object, TResult> ，對象狀態）生成錯誤

Question

當我編譯代碼時遇到此錯誤，我無法弄清楚為什么mcs查找錯誤的函數重載，我使用git作為git當前活動開發版本的最新版本，我檢查了TaskFactory類源代碼和函數存在！

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TaskPoc.cs（30,20）：錯誤CS1502：最佳重載方法匹配` System.Threading.Tasks.TaskFactory.StartNew<bool>(System.Func<bool>, System.Threading.Tasks.TaskCreationOptions) '有一些無效參數/usr/local/lib/mono/4.5/mscorlib.dll（與先前錯誤相關的符號的位置）TaskPoc.cs（30,56）：錯誤CS1503：參數`＃1'無法轉換` System.Func<TaskPoc.State,bool> '表達式以鍵入` System.Func<bool> '

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using System;
using System.Threading;
using System.Threading.Tasks;
namespace TaskPoc
{
  public class State
  {
    public int num;
    public string str;
  }

  public class App
  {
    public static void Main(string[] args)
    {
      State state = new State();
      state.num = 5;
      state.str = "Helllllllllllo";

      TaskCompletionSource<bool> taskCompletionSource = new TaskCompletionSource<bool>(state);
      Task<bool> taskObj = taskCompletionSource.Task;

      Func<State, bool> userMethod = (stateObj) =>
        {
            bool result = TestMethod(stateObj.num, stateObj.str);
            taskCompletionSource.SetResult(result);
            return result;
        };

      Task.Factory.StartNew<bool>(userMethod, state);

      bool result2 = taskObj.Result;
      Console.WriteLine("Result: ", result2.ToString());
    }

    public static bool TestMethod(int num, string str)
    {
      Thread.Sleep(1000);
      Console.WriteLine(string.Format("{0} {1}", num, str));
      return true;
    }
  }
}

Answer 1

我假設您想要此重載： TaskFactory.StartNew <TResult>（Func <Object，TResult>，Object）

如您所見， Func<Object, TResult>必須是Object ，而不是State 。

您可以按以下方式修復代碼：

Func<object, bool> userMethod = (state) =>
{
    State stateObj = (State)state;
    bool result = TestMethod(stateObj.num, stateObj.str);
    taskCompletionSource.SetResult(result);
    return result;
};

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請注意，您的代碼可以縮短，如下所示：

public static void Main(string[] args)
{
    int num = 5;
    string str = "Helllllllllllo";

    Task<bool> taskObj = Task.Run<bool>(() => TestMethod(num, str));

    bool result2 = taskObj.Result;
    Console.WriteLine("Result: {0}", result2);
}