SelectIndexChanged不工作（C＃桌面）

-2

** autopostback -fix无法正常工作！ **SelectIndexChanged不工作（C＃桌面）

我有一个GUI看起来像：

我想说明猫的细节时，它的点击。

我用这个代码是：

private void listBox_Cats_SelectedIndexChanged(object sender, System.EventArgs e) 
     { 
      // Get the currently selected item in the ListBox. 
      Cat cat = listBox_Cats.SelectedItem as Cat; 
      if (cat != null) 
      { 
       tb_ID.Text = cat.ID.ToString(); 
       tb_Name.Text = cat.Name.ToString(); 
       tb_DateArrived.Text = cat.DateArrived.ToString(); 
       tb_IsAdopted.Text = cat.IsAdopted.ToString(); 
       tb_adoptedBy.Text = cat.AdoptedBy.ToString(); 
      } 
     }

然而，当运行，似乎没有任何工作。我究竟做错了什么？

编辑

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

using System.Data.SqlClient; 

using IntegrationTool; 

namespace IntegrationTool 
{ 


    public partial class Form1 : Form 
    { 
     public Form1() 
     { 
      InitializeComponent(); 


      SqlConnection conn = new SqlConnection("Server=.\\SQLEXPRESS;Database=CatShelter;Integrated Security=true"); 
      conn.Open(); 
      SqlCommand cmd = new SqlCommand("SELECT * FROM [dbo].[cats]", conn); 
      SqlDataReader reader = cmd.ExecuteReader(); 

      List<Cat> cats = new List<Cat>(); 


      while (reader.Read()) 
      { 
       Cat c = new Cat(); 
       c.ID = (int)reader["CatID"]; 
       c.Name = (string)reader["Name"]; 
       c.DateArrived = (DateTime)reader["DateArrived"]; 
       c.IsAdopted = (string)reader["IsAdopted"]; 
       c.AdoptedBy = (string)reader["AdoptedBy"]; 

       cats.Add(c); 
      } 

      foreach (Cat c in cats) 
      { 
       Console.WriteLine(c.Name); 
      } 

      reader.Close(); 
      conn.Close(); 

      if (Debugger.IsAttached) 
      { 
       Console.ReadLine(); 
      } 

      listBox_Cats.DataSource = cats; 
      listBox_Cats.DisplayMember = "Name"; 
      listBox_Cats.ValueMember = "ID"; 

     } 

     private void listBox_Cats_SelectedIndexChanged(object sender, System.EventArgs e) 
     { 
      // Get the currently selected item in the ListBox. 
      Cat cat = listBox_Cats.SelectedItem as Cat; 
      if (cat != null) 
      { 
       Console.WriteLine(cat.Name); 
       tb_ID.Text = cat.ID.ToString(); 
       tb_Name.Text = cat.Name.ToString(); 
       tb_DateArrived.Text = cat.DateArrived.ToString(); 
       tb_IsAdopted.Text = cat.IsAdopted.ToString(); 
       tb_adoptedBy.Text = cat.AdoptedBy.ToString(); 
      } 
     } 
    } 
} 

namespace IntegrationTool

{

partial class Form1 
    { 
     /// <summary> 
     /// Required designer variable. 
     /// </summary> 
     private System.ComponentModel.IContainer components = null; 

    /// <summary> 
    /// Clean up any resources being used. 
    /// </summary> 
    /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param> 
    protected override void Dispose(bool disposing) 
    { 
     if (disposing && (components != null)) 
     { 
      components.Dispose(); 
     } 
     base.Dispose(disposing); 
    } 

    #region Windows Form Designer generated code 

    /// <summary> 
    /// Required method for Designer support - do not modify 
    /// the contents of this method with the code editor. 
    /// </summary> 
    private void InitializeComponent() 
    { 
     this.listBox_Cats = new System.Windows.Forms.ListBox(); 
     this.groupBox1 = new System.Windows.Forms.GroupBox(); 
     this.label1 = new System.Windows.Forms.Label(); 
     this.label2 = new System.Windows.Forms.Label(); 
     this.label3 = new System.Windows.Forms.Label(); 
     this.label4 = new System.Windows.Forms.Label(); 
     this.groupBox2 = new System.Windows.Forms.GroupBox(); 
     this.button2 = new System.Windows.Forms.Button(); 
     this.cb_VetCheck = new System.Windows.Forms.CheckBox(); 
     this.label5 = new System.Windows.Forms.Label(); 
     this.tb_Comment = new System.Windows.Forms.TextBox(); 
     this.tb_ID = new System.Windows.Forms.TextBox(); 
     this.tb_DateArrived = new System.Windows.Forms.TextBox(); 
     this.tb_IsAdopted = new System.Windows.Forms.TextBox(); 
     this.tb_adoptedBy = new System.Windows.Forms.TextBox(); 
     this.groupBox3 = new System.Windows.Forms.GroupBox(); 
     this.label6 = new System.Windows.Forms.Label(); 
     this.tb_Name = new System.Windows.Forms.TextBox(); 
     this.groupBox1.SuspendLayout(); 
     this.groupBox2.SuspendLayout(); 
     this.groupBox3.SuspendLayout(); 
     this.SuspendLayout(); 
     // 
     // listBox_Cats 
     // 
     this.listBox_Cats.FormattingEnabled = true; 
     this.listBox_Cats.Location = new System.Drawing.Point(16, 35); 
     this.listBox_Cats.Name = "listBox_Cats"; 
     this.listBox_Cats.Size = new System.Drawing.Size(137, 316); 
     this.listBox_Cats.TabIndex = 0; 
     // 
     // groupBox1 
     // 
     this.groupBox1.Controls.Add(this.tb_Name); 
     this.groupBox1.Controls.Add(this.label6); 
     this.groupBox1.Controls.Add(this.tb_adoptedBy); 
     this.groupBox1.Controls.Add(this.tb_IsAdopted); 
     this.groupBox1.Controls.Add(this.tb_DateArrived); 
     this.groupBox1.Controls.Add(this.tb_ID); 
     this.groupBox1.Controls.Add(this.label4); 
     this.groupBox1.Controls.Add(this.label3); 
     this.groupBox1.Controls.Add(this.label2); 
     this.groupBox1.Controls.Add(this.label1); 
     this.groupBox1.Location = new System.Drawing.Point(252, 31); 
     this.groupBox1.Name = "groupBox1"; 
     this.groupBox1.Size = new System.Drawing.Size(409, 190); 
     this.groupBox1.TabIndex = 1; 
     this.groupBox1.TabStop = false; 
     this.groupBox1.Text = "Details"; 
     // 
     // label1 
     // 
     this.label1.AutoSize = true; 
     this.label1.Location = new System.Drawing.Point(6, 35); 
     this.label1.Name = "label1"; 
     this.label1.Size = new System.Drawing.Size(24, 13); 
     this.label1.TabIndex = 0; 
     this.label1.Text = "ID: "; 
     // 
     // label2 
     // 
     this.label2.AutoSize = true; 
     this.label2.Location = new System.Drawing.Point(6, 95); 
     this.label2.Name = "label2"; 
     this.label2.Size = new System.Drawing.Size(69, 13); 
     this.label2.TabIndex = 1; 
     this.label2.Text = "Date Arrived:"; 
     // 
     // label3 
     // 
     this.label3.AutoSize = true; 
     this.label3.Location = new System.Drawing.Point(6, 123); 
     this.label3.Name = "label3"; 
     this.label3.Size = new System.Drawing.Size(60, 13); 
     this.label3.TabIndex = 2; 
     this.label3.Text = "Is adopted:"; 
     // 
     // label4 
     // 
     this.label4.AutoSize = true; 
     this.label4.Location = new System.Drawing.Point(6, 157); 
     this.label4.Name = "label4"; 
     this.label4.Size = new System.Drawing.Size(65, 13); 
     this.label4.TabIndex = 3; 
     this.label4.Text = "Adopted By:"; 
     // 
     // groupBox2 
     // 
     this.groupBox2.Controls.Add(this.tb_Comment); 
     this.groupBox2.Controls.Add(this.label5); 
     this.groupBox2.Controls.Add(this.cb_VetCheck); 
     this.groupBox2.Location = new System.Drawing.Point(252, 243); 
     this.groupBox2.Name = "groupBox2"; 
     this.groupBox2.Size = new System.Drawing.Size(409, 157); 
     this.groupBox2.TabIndex = 2; 
     this.groupBox2.TabStop = false; 
     this.groupBox2.Text = "Validate"; 
     // 
     // button2 
     // 
     this.button2.Location = new System.Drawing.Point(553, 424); 
     this.button2.Name = "button2"; 
     this.button2.Size = new System.Drawing.Size(107, 31); 
     this.button2.TabIndex = 4; 
     this.button2.Text = "Save"; 
     this.button2.UseVisualStyleBackColor = true; 
     // 
     // cb_VetCheck 
     // 
     this.cb_VetCheck.AutoSize = true; 
     this.cb_VetCheck.Location = new System.Drawing.Point(9, 30); 
     this.cb_VetCheck.Name = "cb_VetCheck"; 
     this.cb_VetCheck.Size = new System.Drawing.Size(76, 17); 
     this.cb_VetCheck.TabIndex = 0; 
     this.cb_VetCheck.Text = "Vet Check"; 
     this.cb_VetCheck.UseVisualStyleBackColor = true; 
     // 
     // label5 
     // 
     this.label5.AutoSize = true; 
     this.label5.Location = new System.Drawing.Point(6, 75); 
     this.label5.Name = "label5"; 
     this.label5.Size = new System.Drawing.Size(51, 13); 
     this.label5.TabIndex = 1; 
     this.label5.Text = "Comment"; 
     // 
     // tb_Comment 
     // 
     this.tb_Comment.Location = new System.Drawing.Point(9, 91); 
     this.tb_Comment.Name = "tb_Comment"; 
     this.tb_Comment.Size = new System.Drawing.Size(288, 20); 
     this.tb_Comment.TabIndex = 2; 
     // 
     // tb_ID 
     // 
     this.tb_ID.Location = new System.Drawing.Point(81, 35); 
     this.tb_ID.Name = "tb_ID"; 
     this.tb_ID.ReadOnly = true; 
     this.tb_ID.Size = new System.Drawing.Size(66, 20); 
     this.tb_ID.TabIndex = 4; 
     // 
     // tb_DateArrived 
     // 
     this.tb_DateArrived.Location = new System.Drawing.Point(81, 92); 
     this.tb_DateArrived.Name = "tb_DateArrived"; 
     this.tb_DateArrived.ReadOnly = true; 
     this.tb_DateArrived.Size = new System.Drawing.Size(66, 20); 
     this.tb_DateArrived.TabIndex = 5; 
     // 
     // tb_IsAdopted 
     // 
     this.tb_IsAdopted.Location = new System.Drawing.Point(81, 120); 
     this.tb_IsAdopted.Name = "tb_IsAdopted"; 
     this.tb_IsAdopted.ReadOnly = true; 
     this.tb_IsAdopted.RightToLeft = System.Windows.Forms.RightToLeft.Yes; 
     this.tb_IsAdopted.Size = new System.Drawing.Size(66, 20); 
     this.tb_IsAdopted.TabIndex = 6; 
     // 
     // tb_adoptedBy 
     // 
     this.tb_adoptedBy.Location = new System.Drawing.Point(81, 154); 
     this.tb_adoptedBy.Name = "tb_adoptedBy"; 
     this.tb_adoptedBy.ReadOnly = true; 
     this.tb_adoptedBy.Size = new System.Drawing.Size(66, 20); 
     this.tb_adoptedBy.TabIndex = 7; 
     // 
     // groupBox3 
     // 
     this.groupBox3.Controls.Add(this.listBox_Cats); 
     this.groupBox3.Location = new System.Drawing.Point(12, 31); 
     this.groupBox3.Name = "groupBox3"; 
     this.groupBox3.Size = new System.Drawing.Size(175, 369); 
     this.groupBox3.TabIndex = 5; 
     this.groupBox3.TabStop = false; 
     this.groupBox3.Text = "Cats"; 
     // 
     // label6 
     // 
     this.label6.AutoSize = true; 
     this.label6.Location = new System.Drawing.Point(7, 61); 
     this.label6.Name = "label6"; 
     this.label6.Size = new System.Drawing.Size(41, 13); 
     this.label6.TabIndex = 8; 
     this.label6.Text = "Name: "; 
     // 
     // tb_Name 
     // 
     this.tb_Name.Location = new System.Drawing.Point(81, 61); 
     this.tb_Name.Name = "tb_Name"; 
     this.tb_Name.ReadOnly = true; 
     this.tb_Name.Size = new System.Drawing.Size(66, 20); 
     this.tb_Name.TabIndex = 9; 
     // 
     // Form1 
     // 
     this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F); 
     this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font; 
     this.ClientSize = new System.Drawing.Size(721, 480); 
     this.Controls.Add(this.groupBox3); 
     this.Controls.Add(this.button2); 
     this.Controls.Add(this.groupBox2); 
     this.Controls.Add(this.groupBox1); 
     this.Name = "Form1"; 
     this.Text = "Form1"; 
     this.groupBox1.ResumeLayout(false); 
     this.groupBox1.PerformLayout(); 
     this.groupBox2.ResumeLayout(false); 
     this.groupBox2.PerformLayout(); 
     this.groupBox3.ResumeLayout(false); 
     this.ResumeLayout(false); 

    } 

    #endregion 

    private System.Windows.Forms.ListBox listBox_Cats; 
    private System.Windows.Forms.GroupBox groupBox1; 
    private System.Windows.Forms.Label label1; 
    private System.Windows.Forms.TextBox tb_adoptedBy; 
    private System.Windows.Forms.TextBox tb_IsAdopted; 
    private System.Windows.Forms.TextBox tb_DateArrived; 
    private System.Windows.Forms.TextBox tb_ID; 
    private System.Windows.Forms.Label label4; 
    private System.Windows.Forms.Label label3; 
    private System.Windows.Forms.Label label2; 
    private System.Windows.Forms.GroupBox groupBox2; 
    private System.Windows.Forms.TextBox tb_Comment; 
    private System.Windows.Forms.Label label5; 
    private System.Windows.Forms.CheckBox cb_VetCheck; 
    private System.Windows.Forms.Button button2; 
    private System.Windows.Forms.GroupBox groupBox3; 
    private System.Windows.Forms.TextBox tb_Name; 
    private System.Windows.Forms.Label label6; 
}

}

来源

2017-07-06 Kahn Kah

所以当你调试时，SelectedItem实际上是一只猫吗？ –

不，我使用'Console.WriteLine（cat.Name）'作为测试目的，并且都不起作用 –

定义'没有任何东西可以工作。如果你把一个断点放在'Cat cat = listBox_Cats.SelectedItem'作为Cat;'它是否触及那个断点？ – mjwills

你listBox_Cats_SelectedIndexChanged不绑定到SelectedIndexChanged事件列表框中的。

应该有你的设计师文件条目看起来像：

this.listBox_Cats.SelectedIndexChanged += new System.EventHandler(this.listBox_Cats_SelectedIndexChanged);

您可以手动添加它，如果它已不存在 - 在InitializeComponent。

来源

2017-07-06 13:48:12 mjwills

非常感谢。我觉得有点愚蠢......希望将来能够帮助别人。谢谢！ –

你的列表框（listBox_Cats）有猫作为一个复杂的类型，以便尝试通过下面的代码来获得所选择的项目，看看有用。

Cat value = (Cat) this.listBox_Cats.SelectedItem;

来源

2017-07-06 13:41:15 Help

仍然一样。感谢您的评论，尽管 –

这与Cat Cat = listBox_Cats.SelectedItem和Cat没有什么不同，除了如果它不是'Cat'就会抛出一个无效的强制转换异常，而另一个只是返回null。这将如何帮助？ –

SelectIndexChanged不工作（C＃桌面）

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