Using ListBox in C#

The source code demonstrates how to use a listbox control in C# - adding, deleting and altering strings.

Description
 
Tools: Windows 2000 & VS.NET SDK Beta 2.0
 
The source code demonstrates how to use a listbox control in C# - adding, deleting and altering strings. The source code is self-explanatory. To compile the code, install .NET SDK including C# compiler and use the following commands on MS-DOS prompt:
 
>csc ListBox.cs 
>ListBox.exe
 
ListBoxDA001.gif 
 
The source code listed in the following table. 
  1. namespace test   
  2. {   
  3.     using System;   
  4.     using System.Drawing;   
  5.     using System.Collections;   
  6.     using System.ComponentModel;   
  7.     using System.Windows.Forms;   
  8.     using System.Data;   
  9.     public class ListBox : System.Windows.Forms.Form   
  10.     {   
  11.         private System.ComponentModel.Container container;   
  12.         private System.Windows.Forms.Button buttonAdd;   
  13.         private System.Windows.Forms.Button buttonClose;   
  14.         private System.Windows.Forms.Button buttonModify;   
  15.         private System.Windows.Forms.Button buttonDelete;   
  16.         private System.Windows.Forms.Button buttonMoveUp;   
  17.         private System.Windows.Forms.Button buttonMoveDown;   
  18.         private System.Windows.Forms.ListBox listbox;   
  19.         private System.Windows.Forms.TextBox textbox;   
  20.         private System.Windows.Forms.Label label;   
  21.         private int nSelectedIndex;   
  22.         //*********SIZE & LOCATION******************//   
  23.         // COMPONENT - BUTTON(s) aligned along X-axis.   
  24.         const int BUTTON_LENGTH = 50;   
  25.         const int BUTTON_HEIGHT = 20;   
  26.         const int FIRSTBUTTON_XPOS = 20;   
  27.         const int FIRSTBUTTON_YPOS =220;   
  28.         const int XSPACING = 70; // (Note: XSPACING >= BUTTON_LENGTH)   
  29.         const int YSPACING = 0;   
  30.         //COMPONENT - MOVE BUTTONS   
  31.         const int MBUTTON_LENGTH = 20;   
  32.         const int MBUTTON_HEIGHT = 20;   
  33.         const int FIRSTMBUTTON_XPOS = 220;   
  34.         const int FIRSTMBUTTON_YPOS =70;   
  35.         const int SECONDMBUTTON_XPOS = 220;   
  36.         const int SECONDMBUTTON_YPOS =100;   
  37.         // COMPONENT - LISTBOX   
  38.         const int LISTBOX_LENGTH = 3*BUTTON_LENGTH;   
  39.         const int LISTBOX_HEIGHT = 6*BUTTON_HEIGHT;   
  40.         const int LISTBOX_XPOS = 50;   
  41.         const int LISTBOX_YPOS = 50;   
  42.         // COMPONENT - LABEL   
  43.         const int LABEL_LENGTH = 50;   
  44.         const int LABEL_HEIGHT = 50;   
  45.         const int LABEL_XPOS = 20; // align it with first button   
  46.         const int LABEL_YPOS = 173;   
  47.         // COMPONENT - TEXTBOX   
  48.         const int TEXTBOX_LENGTH = 120;   
  49.         const int TEXTBOX_HEIGHT = 50;   
  50.         const int TEXTBOX_XPOS = 70;   
  51.         const int TEXTBOX_YPOS = 170;   
  52.         public ListBox() : base()   
  53.         {   
  54.             InitializeComponent();   
  55.         }   
  56.         public override void Dispose()   
  57.         {   
  58.             base.Dispose();   
  59.             container.Dispose();   
  60.         }   
  61.         private void InitializeComponent()   
  62.         {  
  63.             // this   
  64.             this.container = new System.ComponentModel.Container();   
  65.             this.Text="List Box";   
  66.             // buttonAdd   
  67.             this.buttonAdd = new System.Windows.Forms.Button();   
  68.             buttonAdd.Location = new System.Drawing.Point(FIRSTBUTTON_XPOS,FIRSTBUTTON_YPOS);   
  69.             buttonAdd.Text = "&Add";   
  70.             buttonAdd.Size = new System.Drawing.Size(BUTTON_LENGTH,BUTTON_HEIGHT);   
  71.             buttonAdd.Click += new System.EventHandler(this.buttonAdd_Click); buttonAdd.Enabled = false;   
  72.             this.Controls.Add(this.buttonAdd);   
  73.             //buttonModify   
  74.             this.buttonModify = new System.Windows.Forms.Button();   
  75.             buttonModify.Location = new System.Drawing.Point(FIRSTBUTTON_XPOS+XSPACING,FIRSTBUTTON_YPOS+YSPACING);   
  76.             buttonModify.Text = "&Modify";   
  77.             buttonModify.Size = new System.Drawing.Size(BUTTON_LENGTH,BUTTON_HEIGHT);   
  78.             buttonModify.Click += new System.EventHandler(this.buttonModify_Click); buttonModify.Enabled = false;   
  79.             this.Controls.Add(this.buttonModify);   
  80.             //buttonDelete   
  81.             this.buttonDelete = new System.Windows.Forms.Button();   
  82.             buttonDelete.Location = new System.Drawing.Point(FIRSTBUTTON_XPOS+2*XSPACING,FIRSTBUTTON_YPOS+2*YSPACING); buttonDelete.Text = "&Delete";   
  83.             buttonDelete.Size = new System.Drawing.Size(BUTTON_LENGTH,BUTTON_HEIGHT);   
  84.             buttonDelete.Enabled = false;   
  85.             buttonDelete.Click += new System.EventHandler(this.buttonDelete_Click);   
  86.             this.Controls.Add(this.buttonDelete);   
  87.             // buttonClose   
  88.             this.buttonClose = new System.Windows.Forms.Button();   
  89.             buttonClose.Location = new System.Drawing.Point(FIRSTBUTTON_XPOS+3*XSPACING,FIRSTBUTTON_YPOS+3*YSPACING); buttonClose.Text = "&Close";   
  90.             buttonClose.Size = new System.Drawing.Size(BUTTON_LENGTH,BUTTON_HEIGHT);   
  91.             buttonClose.Click += new System.EventHandler(this.buttonClose_Click);   
  92.             this.Controls.Add(this.buttonClose);   
  93.             // listbox   
  94.             this.listbox = new System.Windows.Forms.ListBox();   
  95.             listbox.Location = new System.Drawing.Point(LISTBOX_XPOS,LISTBOX_YPOS);   
  96.             listbox.Size = new System.Drawing.Size(LISTBOX_LENGTH,LISTBOX_HEIGHT);   
  97.             listbox.Click += new System.EventHandler(this.listbox_SelectedIndexChanged);   
  98.             listbox.BackColor = (Color)System.Drawing.SystemColors.Desktop;   
  99.             this.Controls.Add(this.listbox);   
  100.             // label   
  101.             this.label = new System.Windows.Forms.Label();   
  102.             label.Location = new System.Drawing.Point(LABEL_XPOS,LABEL_YPOS);   
  103.             label.Size = new System.Drawing.Size(LABEL_LENGTH,LABEL_HEIGHT);   
  104.             label.Text = "Enter:";   
  105.             this.Controls.Add(this.label);   
  106.             // textbox   
  107.             this.textbox = new System.Windows.Forms.TextBox();   
  108.             textbox.Location = new System.Drawing.Point(TEXTBOX_XPOS,TEXTBOX_YPOS); textbox.Click += new System.EventHandler(this.textbox_Click);   
  109.             textbox.Size = new System.Drawing.Size(TEXTBOX_LENGTH,TEXTBOX_HEIGHT);   
  110.             this.Controls.Add(this.textbox);   
  111.             // buttonMoveUp   
  112.             this.buttonMoveUp = new System.Windows.Forms.Button();   
  113.             buttonMoveUp.Location = new System.Drawing.Point(FIRSTMBUTTON_XPOS,FIRSTMBUTTON_YPOS);   
  114.             buttonMoveUp.Text = "<";   
  115.             buttonMoveUp.Size = new System.Drawing.Size(MBUTTON_LENGTH,MBUTTON_HEIGHT);   
  116.             buttonMoveUp.Click += new System.EventHandler(this.buttonMoveUp_Click);   
  117.             buttonMoveUp.Enabled = false;   
  118.             this.Controls.Add(this.buttonMoveUp);   
  119.             // buttonMoveDown   
  120.             this.buttonMoveDown = new System.Windows.Forms.Button();   
  121.             buttonMoveDown.Location = new System.Drawing.Point(SECONDMBUTTON_XPOS,SECONDMBUTTON_YPOS);   
  122.             buttonMoveDown.Text = ">";   
  123.             buttonMoveDown.Size = new System.Drawing.Size(MBUTTON_LENGTH,MBUTTON_HEIGHT);   
  124.             buttonMoveDown.Click += new System.EventHandler(this.buttonMoveDown_Click);   
  125.             buttonMoveDown.Enabled = false;  
  126.             this.Controls.Add(this.buttonMoveDown);   
  127.         }  
  128.         protected void textbox_Click(Object sender, System.EventArgs e)   
  129.         {   
  130.             this.buttonAdd.Enabled = true;   
  131.             if (this.listbox.Items.Count>0)   
  132.                 EnableAllListBoxButtons();   
  133.         }   
  134.         protected void listbox_SelectedIndexChanged(object sender, System.EventArgs e)  
  135.         {  
  136.             nSelectedIndex = this.listbox.SelectedIndex;   
  137.             string szSelected = (string)this.listbox.SelectedItem;   
  138.             this.textbox.Text = szSelected;   
  139.         }   
  140.         protected void buttonAdd_Click(Object sender, System.EventArgs e)   
  141.         {   
  142.             if (this.textbox.Text !="")   
  143.             {  
  144.                 this.listbox.Items.Add(this.textbox.Text);   
  145.                 this.textbox.Text = "";   
  146.                 EnableAllListBoxButtons();   
  147.             }   
  148.         }   
  149.         protected void buttonModify_Click(Object sender, System.EventArgs e)   
  150.         {   
  151.             this.listbox.Items[nSelectedIndex] = this.textbox.Text;   
  152.         }   
  153.         protected void buttonDelete_Click(Object sender, System.EventArgs e)   
  154.         {   
  155.             nSelectedIndex = this.listbox.SelectedIndex;   
  156.             this.listbox.Items.Remove(nSelectedIndex);   
  157.             System.Console.WriteLine("Remove fn does not work...");   
  158.         }   
  159.         protected void buttonClose_Click(Object sender, System.EventArgs e)   
  160.         {   
  161.             this.Close();   
  162.         }   
  163.         protected void buttonMoveUp_Click(Object sender, System.EventArgs e)   
  164.         {   
  165.             if (this.listbox.SelectedIndex >0)   
  166.                 this.listbox.SelectedIndex--;   
  167.         }   
  168.         protected void buttonMoveDown_Click(Object sender, System.EventArgs e)   
  169.         {   
  170.             if (this.listbox.SelectedIndex < this.listbox.Items.Count-1)   
  171.                 this.listbox.SelectedIndex++;   
  172.         }   
  173.         private void EnableAllListBoxButtons()   
  174.         {  
  175.             this.buttonAdd.Enabled = true;   
  176.             this.buttonModify.Enabled = true;   
  177.             this.buttonDelete.Enabled = true;   
  178.             this.buttonMoveUp.Enabled = true;   
  179.             this.buttonMoveDown.Enabled = true;   
  180.         }   
  181.         [STAThread]   
  182.         public static void Main(string[] args)   
  183.         {   
  184.             Application.Run(new ListBox());   
  185.         }   
  186.     } // class   
  187. // namespace   
Further Readings
 
Here are more articles on ListBox control.