1.原始的委托 (.net 1.0)

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;using System.Threading;namespace WindowsFormsAppLINQ{    public partial class Form1 : Form    {        public delegate void MyDelegate();        public Form1()        {            InitializeComponent();            MyDelegate myDelegate = new MyDelegate(DoSomething);            myDelegate();        }        public void DoSomething()        {            MessageBox.Show("Hello");        }    }}

2.Action预定义委托, 节省了委托的定义.

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace WindowsFormsAppLINQ{    public partial class Form2 : Form    {        public Form2()        {            InitializeComponent();            Action myDelegate = new Action(DoSomething);            myDelegate();        }        public void DoSomething()        {            MessageBox.Show("Hello");         }    }}

3.Lambda表达式, 再省掉方法定义.

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace WindowsFormsAppLINQ{    public partial class Form3 : Form    {        public Form3()        {            InitializeComponent();            Action myDelegate = new Action(() => { MessageBox.Show("Hello"); });            myDelegate();        }           }}

4.一对小括号, 直接执行.

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Linq;using System.Text;using System.Windows.Forms;namespace WindowsFormsAppLINQ{    public partial class Form4 : Form    {        public Form4()        {            InitializeComponent();            new Action(() => { MessageBox.Show("Hello"); })();        }    }}

 总结，()=> {} 这个lambda表达式就是一个无参数的委托及具体方法的组合体，这是一个常规的套路，可以直接记住。