泛型集合List的添加、访问、遍历和删除

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;

namespace MySchool
{
    public partial class Form1 : Form
    {
       
        public Form1()
        {
            InitializeComponent();
        }
        List<Student> allstudent = new List<Student>();

        //建立集合
        private void btnsearch_Click(object sender, EventArgs e)
        {
            Student s1 = new Student("张三", 18, "男");
            Student s2 = new Student("刘德华", 50, "男");
            Student s3 = new Student("周星驰", 40, "男");
            Student s4 = new Student("周杰伦", 30, "男");
            allstudent.Add(s1);
            allstudent.Add(s2);
            allstudent.Add(s3);
            allstudent.Add(s4);
            AddAllStdent();
        }
        //显示信息
        public void AddAllStdent()
        {
            //循环遍历所有集合中对象，添加到控件中，
            //在循环中实例化listviewitem对象，添加一个信息
            livxinxi.Items.Clear();//清空控件
            foreach(Student stu in allstudent)
            {
                //添加项
                ListViewItem item = new ListViewItem(stu.Name);
                item.SubItems.Add(stu.Age.ToString());
                item.SubItems.Add(stu.Sex);
                livxinxi.Items.Add(item);
            }
        }
        //添加一个元素
        private void btnadd_Click(object sender, EventArgs e)
        {
            try
            {
                Student s1 = new Student("张三丰", 20, "男");
                allstudent.Add(s1);
                AddAllStdent();
            }
            catch
            {        
               
            }
        }
        //删除一个元素
        private void btnclear_Click(object sender, EventArgs e)
        {
            try
            {
                int index = livxinxi.SelectedItems[0].Index;
                allstudent.RemoveAt(index);
                AddAllStdent();
            }
            catch
            {

            }
        }
        //弹出消息框
        private void livxinxi_SelectedIndexChanged(object sender, EventArgs e)
        {
            try
            {
                int index = livxinxi.SelectedItems[0].Index;
                MessageBox.Show(allstudent[index].SayHi());
            }
            catch
            {
              
            }

        }
    }
}