C#: Delegate and Event

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test.Other
{
    public class TestDelegateAndEvent
    {
        public delegate void TestDelegate();
        public event TestDelegate TestEventHandler;

        public void Test()
        {
            TestDelegate testDelegate = new TestDelegate(Test1);
            TestEventHandler += new TestDelegate(Test1);

            testDelegate();
            TestEventHandler();
        }
        public void Test1()
        {
        }
    }
}

TestDelegateAndEvent.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test.Other
{
    class Program
    {
        //public static delegate void TestDelegate();
        //public static event TestDelegate TestEventHandler;
        static void Main(string[] args)
        {
            // Delegate can be triggered directly
            //TestDelegate testDelegate = new TestDelegate(Test);
            //testDelegate();


            //TestDelegateAndEvent test = new TestDelegateAndEvent();
            //test.TestEventHandler += Test;

            // Error: The delegate inner the class is private even if the type is public.
            // test.TestDelegate();

            // Error: Event can't be triggered directly.
            //test.TestEventHandler();

            Console.ReadLine();
        }

        public static void Test()
        {
            Console.WriteLine("test");
        }
    }
}

Program.cs

總結：

1. Delegate能夠將方法做爲另一個方法的參數帶入其中進行運算；

2. 實際上Delegate和Event都是類，Event是一種特殊類型的Delegate；

3. 類內的Delegate不能被對象調用，即使這個delegate是Public的；

4. delegate和event都重載了+=，-=， 可是delegate能夠用=直接賦值，可是event不能夠；

5. delegate和event都不能由對象直接觸發；

6. delegate和event都不能是static.