事件例程

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 theEvent
{
    //自定义事件参数，继承EventArgs基类
    public class myEventArgs : EventArgs
    {
        public string label;
    }

    //发布者
    public partial class FormB : Form
    {
        public FormB()
        {
            InitializeComponent();
        }

        public event EventHandler<myEventArgs> myEvent;//使用自定义泛型委托

        //由发布者来触发事件，让订阅者来响应
        private void buttonB_Click(object sender, EventArgs e)
        {
            myEventArgs args = new myEventArgs();
            args.label = "FUCK YOU!";
            if (myEvent != null)
            {
                myEvent(this, args);//引发事件
            }
            this.Close();
        }
    }
}

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 theEvent
{
    //订阅者
    public partial class FormA : Form
    {
        FormB b = null;

        public FormA()
        {
            InitializeComponent();

            b = new FormB();//实例化一个发布者的类
            //订阅该发布者的事件
            b.myEvent += myEventFunction;//监听B窗体事件
        }

        void myEventFunction(object source, myEventArgs e)
        {
            labelA.Text = e.label;
        }

        private void buttonA_Click(object sender, EventArgs e)
        {
            b.Show();
        }
    }
}