c#基础知识篇-委托Func和Action区别

Func指向的方法必须有返回值。Action指向的方法必须无返回值。

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static void TestA() {     Console.WriteLine("无参无返回值方法");     Console.WriteLine("TestA线程,当前线程ID：" + Thread.CurrentThread.ManagedThreadId); }   static void TestB(int i, int j) {     Console.WriteLine("有参无返回值方法");     Console.WriteLine("TestB线程,当前线程ID：" + Thread.CurrentThread.ManagedThreadId); }   static int TestC() {     Thread.Sleep(1000);     Console.WriteLine("无参有返回值方法");     Console.WriteLine("TestC线程,当前线程ID：" + Thread.CurrentThread.ManagedThreadId);     return 1; }   static string TestD(int i, int j) {     Thread.Sleep(2000);     Console.WriteLine("有参有返回值方法");     Console.WriteLine("TestD线程,当前线程ID：" + Thread.CurrentThread.ManagedThreadId);     return (i + j).ToString(); }

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Action actionA = TestA; actionA.BeginInvoke(null, null);   Action<int, int> actionB = TestB; actionB.BeginInvoke(2, 3, null, null);   Func<int> funC = TestC; IAsyncResult resultC = funC.BeginInvoke(null, null); while (!resultC.IsCompleted) {     Console.WriteLine("线程执行中，未结束"); }   int valueC = funC.EndInvoke(resultC); Console.WriteLine("得到的值：" + valueC + "，当前线程ID：" + Thread.CurrentThread.ManagedThreadId + "");   Func<int, int, string> funD = TestD; IAsyncResult resultD = funD.BeginInvoke(1, 2, null, null); while (!resultD.IsCompleted) {     Console.WriteLine("线程执行中，未结束"); }   string valueD = funD.EndInvoke(resultD); Console.WriteLine("得到的值：" + valueD + "，当前线程ID：" + Thread.CurrentThread.ManagedThreadId + "");   Console.WriteLine("主线程结束,当前主线程ID：" + Thread.CurrentThread.ManagedThreadId);