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CheckedListBox Class

Displays a ListBox in which a check box is displayed to the left of each item.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

[ComVisibleAttribute(true)]
[ClassInterfaceAttribute(ClassInterfaceType.AutoDispatch)]
[LookupBindingPropertiesAttribute]
public class CheckedListBox : ListBox

This control presents a list of items that the user can navigate by using the keyboard or the scrollbar on the right side of the control. The user can place a check mark by one or more items and the checked items can be navigated with the CheckedListBox.CheckedItemCollection and CheckedListBox.CheckedIndexCollection.

To add objects to the list at run time, assign an array of object references with the AddRange method. The list then displays the default string value for each object. You can add individual items to the list with the Add method.

The CheckedListBox object supports three states through the CheckState enumeration: Checked, Indeterminate, and Unchecked. You must set the state of Indeterminate in the code because the user interface for a CheckedListBox does not provide a mechanism to do so.

If UseTabStops is true, the CheckedListBox will recognize and expand tab characters in an item's text, creating columns. These tab stops are preset and cannot be changed. To use custom tab stops, set UseTabStops to false, set UseCustomTabOffsets to true, and add the custom values to the CustomTabOffsets collection.

NoteNote:

If the UseCompatibleTextRendering property is false, the CustomTabOffsets property will be ignored and replaced with standard tab offsets.

The CheckedListBox class supports the following three indexed collections:

Collection

Encapsulating Class

All items contained in the CheckedListBox control.

CheckedListBox.ObjectCollection

Checked items (including items in an indeterminate state), which is a subset of the items contained in the CheckedListBox control.

CheckedListBox.CheckedItemCollection

Checked indexes, which is a subset of the indexes into the items collection. These indexes specify items in a checked or indeterminate state.

CheckedListBox.CheckedIndexCollection

The following three tables are examples of the three indexed collections that the CheckedListBox class supports.

The first table provides an example of the indexed collection of items in the control (all items contained in the control).

Index

Item

Check State

0

Object 1

Unchecked

1

Object 2

Checked

2

Object 3

Unchecked

3

Object 4

Indeterminate

4

Object 5

Checked

The second table provides an example of the indexed collection of the checked items.

Index

Item

0

Object 2

1

Object 4

2

Object 5

The third table provides an example of the indexed collection of indexes of checked items.

Index

Index of Item

0

1

1

3

2

4

The following example illustrates how you can use the methods, properties, and collections of a CheckedListBox. This is a complete sample ready to run once you have copied it to your project. You can check and uncheck items, use the text box to add items and once you have clicked the save button, clear the checked items.

namespace WindowsApplication1
{
   using System;
   using System.Drawing;
   using System.Collections;
   using System.ComponentModel;
   using System.Windows.Forms;
   using System.Data;
   using System.IO ;

   public class Form1 : System.Windows.Forms.Form
   {
      private System.Windows.Forms.CheckedListBox checkedListBox1;
      private System.Windows.Forms.TextBox textBox1;
      private System.Windows.Forms.Button button1;
      private System.Windows.Forms.Button button2;
      private System.Windows.Forms.ListBox listBox1;
      private System.Windows.Forms.Button button3;
        private System.ComponentModel.Container components;

      public Form1()
      {
            InitializeComponent();

         // Sets up the initial objects in the CheckedListBox.
            string[] myFruit = {"Apples", "Oranges","Tomato"};
         checkedListBox1.Items.AddRange(myFruit);

            // Changes the selection mode from double-click to single click.
         checkedListBox1.CheckOnClick = true;
      }

      protected override void Dispose( bool disposing )
	  {
		if( disposing )
		{
			if (components != null) 
			{
			  components.Dispose();
			}
		}
		base.Dispose( disposing );
	  }

      private void InitializeComponent()
      {
         this.components = new System.ComponentModel.Container();
         this.textBox1 = new System.Windows.Forms.TextBox();
         this.checkedListBox1 = new System.Windows.Forms.CheckedListBox();
         this.listBox1 = new System.Windows.Forms.ListBox();
         this.button1 = new System.Windows.Forms.Button();
         this.button2 = new System.Windows.Forms.Button();
         this.button3 = new System.Windows.Forms.Button();
         this.textBox1.Location = new System.Drawing.Point(144, 64);
         this.textBox1.Size = new System.Drawing.Size(128, 20);
         this.textBox1.TabIndex = 1;
         this.textBox1.TextChanged += new System.EventHandler(this.textBox1_TextChanged);
         this.checkedListBox1.Location = new System.Drawing.Point(16, 64);
         this.checkedListBox1.Size = new System.Drawing.Size(120, 184);
         this.checkedListBox1.TabIndex = 0;
         this.checkedListBox1.ItemCheck += new System.Windows.Forms.ItemCheckEventHandler(this.checkedListBox1_ItemCheck);
         this.listBox1.Location = new System.Drawing.Point(408, 64);
         this.listBox1.Size = new System.Drawing.Size(128, 186);
         this.listBox1.TabIndex = 3;
         this.button1.Enabled = false;
         this.button1.Location = new System.Drawing.Point(144, 104);
         this.button1.Size = new System.Drawing.Size(104, 32);
         this.button1.TabIndex = 2;
         this.button1.Text = "Add Fruit";
         this.button1.Click += new System.EventHandler(this.button1_Click);
         this.button2.Enabled = false;
         this.button2.Location = new System.Drawing.Point(288, 64);
         this.button2.Size = new System.Drawing.Size(104, 32);
         this.button2.TabIndex = 2;
         this.button2.Text = "Show Order";
         this.button2.Click += new System.EventHandler(this.button2_Click);
         this.button3.Enabled = false;
         this.button3.Location = new System.Drawing.Point(288, 104);
         this.button3.Size = new System.Drawing.Size(104, 32);
         this.button3.TabIndex = 2;
         this.button3.Text = "Save Order";
         this.button3.Click += new System.EventHandler(this.button3_Click);
         this.ClientSize = new System.Drawing.Size(563, 273);
         this.Controls.AddRange(new System.Windows.Forms.Control[] {this.listBox1,
                                                        this.button3,
                                                        this.button2,
                                                        this.button1,
                                                        this.textBox1,
                                                        this.checkedListBox1});
         this.Text = "Fruit Order";
      }

      [STAThread]
      public static void Main(string[] args) 
      {
         Application.Run(new Form1());
      }

      // Adds the string if the text box has data in it. 
      private void button1_Click(object sender, System.EventArgs e)
      {
         if(textBox1.Text != "")
         {
            if(checkedListBox1.CheckedItems.Contains(textBox1.Text)== false)
               checkedListBox1.Items.Add(textBox1.Text,CheckState.Checked);
            textBox1.Text = "";
         }

      }
      // Activates or deactivates the Add button. 
      private void textBox1_TextChanged(object sender, System.EventArgs e)
      {
         if (textBox1.Text == "")
         {
            button1.Enabled = false;
         }
         else
         {
            button1.Enabled = true;
         }

        }

      // Moves the checked items from the CheckedListBox to the listBox. 
      private void button2_Click(object sender, System.EventArgs e)
      {
         listBox1.Items.Clear();
         button3.Enabled=false;
         for (int i=0; i< checkedListBox1.CheckedItems.Count;i++)
         {
            listBox1.Items.Add(checkedListBox1.CheckedItems[i]);
         }
         if (listBox1.Items.Count>0)
            button3.Enabled=true;

      }
        // Activates the move button if there are checked items. 
      private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
      {
         if(e.NewValue==CheckState.Unchecked)
         {
            if(checkedListBox1.CheckedItems.Count==1)
            {
               button2.Enabled = false;
            }
         }
         else
         {
            button2.Enabled = true;
         }
      }

        // Saves the items to a file. 
      private void button3_Click(object sender, System.EventArgs e)
      {   
         // Insert code to save a file.
         listBox1.Items.Clear();
         IEnumerator myEnumerator;
         myEnumerator = checkedListBox1.CheckedIndices.GetEnumerator();
         int y;
         while (myEnumerator.MoveNext() != false)
         {
            y =(int) myEnumerator.Current;
            checkedListBox1.SetItemChecked(y, false);
         }
         button3.Enabled = false ;
      }        
    }
}

System.Object
  System.MarshalByRefObject
    System.ComponentModel.Component
      System.Windows.Forms.Control
        System.Windows.Forms.ListControl
          System.Windows.Forms.ListBox
            System.Windows.Forms.CheckedListBox

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

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