winform

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

namespace WinApp02_ListBox
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        //
        // 加载窗口
        private void Form1_Load(object sender, EventArgs e)
        {
            // 绑定列表数据
            BindListData();
        }
        /// <summary>
        /// 绑定列表数据
        /// </summary>
        private void BindListData()
        {
            // 绑定多个图书信息实例
            //List<Book> lstBook = new List<Book>()
            //{ 
            //    new Book() { ID = 1, Title = "ASP.NET", Price = 36.50m } ,
            //    new Book() { ID = 2, Title = "C#本质论", Price = 55.80m } ,
            //    new Book() { ID = 3, Title = "CRL", Price = 87.00m } ,
            //    new Book() { ID = 4, Title = "ADO.NET", Price = 42.50m } ,
            //    new Book() { ID = 5, Title = "Python", Price = 38.40m } 
            //};

            // 将lstBook中的数据遍历出来并存储到listBox1中.
            //foreach (Book book in lstBook)
            //{
            //    // 自定义类型或非字符串类型,默认会显示其完全限定名(命名空间.类名: WinApp02_ListBox.Book)
            //    // 所以必须重写Book类的ToString()方法
            //    listBox1.Items.Add(book);
            //}

            List<Book> lstBook = new List<Book>();
            lstBook.Add(new Book() { ID = 1, Title = "ASP.NET", Price = 36.50m });
            lstBook.Add(new Book() { ID = 2, Title = "C#本质论", Price = 55.80m });
            lstBook.Add(new Book() { ID = 3, Title = "CRL", Price = 87.00m });
            lstBook.Add(new Book() { ID = 4, Title = "ADO.NET", Price = 42.50m });
            lstBook.Add(new Book() { ID = 5, Title = "Python", Price = 38.40m });

            // 指定数据源一次性绑定数据(同样,必须重写ToString()方法,否则即显示【命名空间.类名】
            listBox1.DataSource = lstBook;
            // 将对象属性作为列表显示的文字; 即Book.Title
            listBox1.DisplayMember = "Title"; 
            // 指定对象的值属性作为"值"字段,可以用ID或者Price;
            listBox1.ValueMember = "ID";
           // listBox1.ValueMember = "Price";

        }

        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            //GetSelectedInfo_Foreach();
            GetSelectedInfo_Linq();

        }
        /// 获取选中的信息, foreach写法
        /// 
        private void GetSelectedInfo_Foreach()
        {
            if (-1 == listBox1.SelectedIndex)
            {
                MessageBox.Show("当前未选中任何项");
                return;
            }

            // 获取当前所有选中项的索引
            string index = "";
            foreach(int i in listBox1.SelectedIndices)
            {
                index += i.ToString()+" , ";
            }
            
            // 获取当前所有选中项的ID,Title,Price
            string ids = "";
            string titles = "";
            string prices = "";
            foreach (Book book in listBox1.SelectedItems)
            {
                ids += book.ID + " , ";
                titles += book.Title + " , ";
                prices += book.Price + " , ";
            }
            label1.Text = "当前选中项的索引: " + index;                     //+ listBox1.SelectedIndex.ToString();
            label2.Text = "选中的图书ID分别为: " + ids;
            label3.Text = "选中的图书名称分别为: " + titles;
            label4.Text = "选中的图书价格分别为: " + prices;
        }

        /// GetSelectedInfo_Linq: 获取选中的信息, Linq写法
        ///
        private void GetSelectedInfo_Linq()
        {
            if ( -1 == listBox1.SelectedIndex )
            {
                MessageBox.Show("当前未选中任何项");
                return;
            }

            string index = "";
            foreach (int i in listBox1.SelectedIndices)
            {
                index += i.ToString() + ", ";
            }
            // Linq写法
            label1.Text = "当前选中项的索引: " + index;
            label2.Text =  "选中的图书ID分别为: "+ string.Join(", ", listBox1.SelectedItems.Cast<Book>().Select(book => book.ID).ToArray());
            label3.Text = "选中的图书名称分别为: " + string.Join(", ",listBox1.SelectedItems.Cast<Book>().Select(book => book.Title).ToArray());
            label4.Text = "选中的图书价格分别为: " + string.Join(", ", listBox1.SelectedItems.Cast<Book>().Select(book => book.Price).ToArray());
        }

    }
}