新手求教 资源管理器 listview的问题

[温水煮蛙的蛙]

using System;
 using System.Windows.Forms;
 using System.IO;


 namespace WindowsExplorer
 {
     public partial class Form1 : Form
     {
         public Form1()
         {
             InitializeComponent();
         }

         private void Form1_SizeChanged(object sender, EventArgs e)
         {
             this.tscAdress.Width = this.toolStrip2.Width - 90;
         }

         private void Form1_Load(object sender, EventArgs e)
         {
             
             TreeNode Mycomputer = this.treeView1.Nodes[0];
             DriveInfo[] drivers = DriveInfo.GetDrives();
             //循环添加我的电脑的子节点
            foreach (DriveInfo driver in drivers)
             {
                 TreeNode node = new TreeNode(driver.Name);
                 node.ImageKey = "drive.png";
                 node.SelectedImageKey = "drive.png";
                 node.Tag = driver.RootDirectory.FullName;
                 Mycomputer.Nodes.Add(node);
                 //添加到listView
               this.listView1.Items.Add(new ListViewItem(new string[] { driver.Name, "磁盘", "", "" }, "drive.png"));
             }

            
           

         }
         /// <summary>
         /// 添加被选中项的子节点
        /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void treeView1_AfterExpand(object sender, TreeViewEventArgs e)
         {
             foreach (TreeNode node in e.Node.Nodes)
             {

                 DirectoryInfo driver = new DirectoryInfo(node.Tag.ToString());
                 DirectoryInfo[] subdrivers = null;

                 //跳过无访问权限的文件
                try { subdrivers = driver.GetDirectories(); }
                 catch (UnauthorizedAccessException) { }
                 catch (IOException) { }

                 if (subdrivers != null)
                 {
                     foreach (DirectoryInfo subdriver in subdrivers)
                     {
                         TreeNode subNode = new TreeNode(subdriver.Name);
                         subNode.ImageKey = "folder_add.png";
                         subNode.SelectedImageKey = "folder.png";
                         subNode.Tag = subdriver.FullName;
                         node.Nodes.Add(subNode);
                     }
                 }
             }
         }
         /// <summary>
         /// 列表显示
        /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
         private void treeView1_AfterSelect(object sender, TreeViewEventArgs e)
         {//地址栏显示
            if (e.Action == TreeViewAction.ByKeyboard || e.Action == TreeViewAction.ByMouse)
             {
                 if (e.Node.Tag == null)
                 {
                     this.tscAdress.Text = e.Node.Text;
                 }
                 else
                 {
                     this.tscAdress.Text = e.Node.Tag.ToString();
                 }
             }

            
             this.listView1.Items.Clear();
             if (e.Node.Tag != null)
             {
                 string path = e.Node.Tag.ToString();
                 DirectoryInfo folder = new DirectoryInfo(path);
                 //填充文件夹
                DirectoryInfo[] subfolders = null;
                 try
                 {
                     subfolders = folder.GetDirectories();

                 }
                 catch (UnauthorizedAccessException)
                 {

                 }
                 if (subfolders != null)
                 {
                     foreach (DirectoryInfo subfolder in subfolders)
                     {
                         listView1.Items.Add(new ListViewItem(new string[] { subfolder.Name, "文件夹", "", "" }, "folder.png"));
                     }
                 }

                 //填充文件
                try
                 {
                     FileInfo[] files = folder.GetFiles();


                     foreach (FileInfo file in files)
                     {
                         listView1.Items.Add(new ListViewItem(new string[] { file.Name, "文件", GetFileSize(file), file.LastWriteTime.ToString() }, "page.png"));

                     }
                 }
                 catch (UnauthorizedAccessException)
                 { }
             }

         }
  private void listView1_MouseDoubleClick(object sender, MouseEventArgs e)
         {
             
             try
             {                
                 string path = this.listView1.SelectedItems[0].Tag.ToString();               
                 DirectoryInfo folder = new DirectoryInfo(path);
                 FileInfo[] files = folder.GetFiles();
                
                 this.listView1.Items.Clear();//清空列表
              
                 //填充文件夹
                          
                DirectoryInfo[] subfolders = folder.GetDirectories();        
                 if (subfolders != null)
                 {
                     foreach (DirectoryInfo subfolder in subfolders)
                     {
                         listView1.Items.Add(new ListViewItem(new string[] { subfolder.Name, "文件夹", "", "" }, "folder.png"));
                     }
                 }
                 //填充文件
               
                 foreach (FileInfo file in files)
                 {
                     listView1.Items.Add(new ListViewItem(new string[] { file.Name, "文件", GetFileSize(file), file.LastWriteTime.ToString() }, "page.png"));

                 }
             }
             catch (UnauthorizedAccessException)
             { }          
             catch (NullReferenceException)
             { } 
  
         } 
     }
 }
 //load中  添加到listView
   //            this.listView1.Items.Add(new ListViewItem(new string[] { driver.Name, "磁盘", "", "" }, "drive.png"));
//没效果。
// listView1_MouseDoubleClick中string path = this.listView1.SelectedItems[0].Tag.ToString();     出现异常
 //新手求教。 

[温水煮蛙的蛙]

需要解决空值的问题 我尝试SelectedItems[0].Text 有值 但是用SelectedItems[0].Tag 是空值

[exception92]

SelectedItems[0].Tag 这两者 某个为空。

[exception92]

http://blog.csdn.net/chen_zw/article/details/7910324 新手多看 详解。

[小生我怕怕]

http://blog.csdn.net/chen_zw/article/details/7910324