CheckState Enumeration

Specifies the state of a control, such as a check box, that can be checked, unchecked, or set to an indeterminate state.

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

Public Enumeration CheckState
Dim instance As CheckState

public enum CheckState
public enum CheckState

 Member nameDescription
Supported by the .NET Compact FrameworkCheckedThe control is checked. 
Supported by the .NET Compact FrameworkIndeterminateThe control is indeterminate. An indeterminate control generally has a shaded appearance. 
Supported by the .NET Compact FrameworkUncheckedThe control is unchecked. 

Multiple methods in CheckBox, CheckedListBox, and ItemCheckEventArgs use this enumeration.


Use an indeterminately checked control when you do not want to set a default value.

The following code example demonstrates the use of the CheckState enumeration.

Option Explicit
Option Strict

Imports System
Imports System.Drawing
Imports System.Collections
Imports System.ComponentModel
Imports System.Windows.Forms
Imports System.Data
Imports System.IO

Namespace WindowsApplication1
    Public Class Form1
        Inherits System.Windows.Forms.Form
        Private WithEvents checkedListBox1 As System.Windows.Forms.CheckedListBox
        Private WithEvents textBox1 As System.Windows.Forms.TextBox
        Private WithEvents button1 As System.Windows.Forms.Button
        Private WithEvents button2 As System.Windows.Forms.Button
        Private WithEvents listBox1 As System.Windows.Forms.ListBox
        Private WithEvents button3 As System.Windows.Forms.Button
        Private components As System.ComponentModel.Container
        Public Sub New()
            ' Sets up the initial objects in the CheckedListBox.
            Dim myFruit As String() =  {"Apples", "Oranges", "Tomato"}
            ' Changes the selection mode from double-click to single click.
            checkedListBox1.CheckOnClick = True
        End Sub 'New
        Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
            If disposing Then
                If Not (components Is Nothing) Then
                End If
            End If
        End Sub
        Private Sub InitializeComponent()
            Me.components = New System.ComponentModel.Container()
            Me.textBox1 = New System.Windows.Forms.TextBox()
            Me.checkedListBox1 = New System.Windows.Forms.CheckedListBox()
            Me.listBox1 = New System.Windows.Forms.ListBox()
            Me.button1 = New System.Windows.Forms.Button()
            Me.button2 = New System.Windows.Forms.Button()
            Me.button3 = New System.Windows.Forms.Button()
            Me.textBox1.Location = New System.Drawing.Point(144, 64)
            Me.textBox1.Size = New System.Drawing.Size(128, 20)
            Me.textBox1.TabIndex = 1
            Me.checkedListBox1.Location = New System.Drawing.Point(16, 64)
            Me.checkedListBox1.Size = New System.Drawing.Size(120, 184)
            Me.checkedListBox1.TabIndex = 0
            Me.listBox1.Location = New System.Drawing.Point(408, 64)
            Me.listBox1.Size = New System.Drawing.Size(128, 186)
            Me.listBox1.TabIndex = 3
            Me.button1.Enabled = False
            Me.button1.Location = New System.Drawing.Point(144, 104)
            Me.button1.Size = New System.Drawing.Size(104, 32)
            Me.button1.TabIndex = 2
            Me.button1.Text = "Add Fruit"
            Me.button2.Enabled = False
            Me.button2.Location = New System.Drawing.Point(288, 64)
            Me.button2.Size = New System.Drawing.Size(104, 32)
            Me.button2.TabIndex = 2
            Me.button2.Text = "Show Order"
            Me.button3.Enabled = False
            Me.button3.Location = New System.Drawing.Point(288, 104)
            Me.button3.Size = New System.Drawing.Size(104, 32)
            Me.button3.TabIndex = 2
            Me.button3.Text = "Save Order"
            Me.ClientSize = New System.Drawing.Size(563, 273)
            Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.listBox1, Me.button3, Me.button2, Me.button1, Me.textBox1, Me.checkedListBox1})
            Me.Text = "Fruit Order"
        End Sub 'InitializeComponent
        <STAThread()> _
        Public Shared Sub Main()
            Application.Run(New Form1())
        End Sub 'Main
        ' Adds the string if the text box has data in it.
        Private Sub button1_Click(sender As Object, _
                e As System.EventArgs) Handles button1.Click
            If textBox1.Text <> "" Then
                If checkedListBox1.CheckedItems.Contains(textBox1.Text) = False Then
                    checkedListBox1.Items.Add(textBox1.Text, CheckState.Checked)
                End If
                textBox1.Text = ""
            End If
        End Sub 'button1_Click
        ' Activates or deactivates the Add button.
        Private Sub textBox1_TextChanged(sender As Object, _
                e As System.EventArgs) Handles textBox1.TextChanged
            If textBox1.Text = "" Then
                button1.Enabled = False
                button1.Enabled = True
            End If
        End Sub 'textBox1_TextChanged
        ' Moves the checked items from the CheckedListBox to the listBox.
        Private Sub button2_Click(sender As Object, _
                e As System.EventArgs) Handles button2.Click
            button3.Enabled = False
            Dim i As Integer
            For i = 0 To checkedListBox1.CheckedItems.Count - 1
            Next i
            If listBox1.Items.Count > 0 Then
                button3.Enabled = True
            End If 
        End Sub 'button2_Click
        ' Activates the move button if there are checked items.
        Private Sub checkedListBox1_ItemCheck(sender As Object, _
                e As ItemCheckEventArgs) Handles checkedListBox1.ItemCheck
            If e.NewValue = CheckState.Unchecked Then
                If checkedListBox1.CheckedItems.Count = 1 Then
                    button2.Enabled = False
                End If
                button2.Enabled = True
            End If
        End Sub 'checkedListBox1_ItemCheck
        ' Saves the items to a file.
        Private Sub button3_Click(sender As Object, _
                e As System.EventArgs) Handles button3.Click
            ' Insert code to save a file.
            Dim myEnumerator As IEnumerator
            myEnumerator = checkedListBox1.CheckedIndices.GetEnumerator()
            Dim y As Integer
            While myEnumerator.MoveNext() <> False
                y = CInt(myEnumerator.Current)
                checkedListBox1.SetItemChecked(y, False)
            End While
            button3.Enabled = False
        End Sub 'button3_Click
    End Class 'Form1
End Namespace 'WindowsApplication1

import System.*;
import System.Drawing.*;
import System.Collections.*;
import System.ComponentModel.*;
import System.Windows.Forms.*;
import System.Data.*;
import System.IO.*;
public class Form1 extends 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()
        // Sets up the initial objects in the CheckedListBox.
        String myFruit[] =  { "Apples", "Oranges", "Tomato" };
        // Changes the selection mode from double-click to single click.
    } //Form1

    protected void Dispose(boolean disposing)
        if (disposing) {
            if (components != null) {
    } //Dispose

    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.set_Location(new System.Drawing.Point(144, 64));
        this.textBox1.set_Size(new System.Drawing.Size(128, 20));
        this.textBox1.add_TextChanged(new System.EventHandler(
        this.checkedListBox1.set_Location(new System.Drawing.Point(16, 64));
        this.checkedListBox1.set_Size(new System.Drawing.Size(120, 184));
            new System.Windows.Forms.ItemCheckEventHandler(
        this.listBox1.set_Location(new System.Drawing.Point(408, 64));
        this.listBox1.set_Size(new System.Drawing.Size(128, 186));
        this.button1.set_Location(new System.Drawing.Point(144, 104));
        this.button1.set_Size(new System.Drawing.Size(104, 32));
        this.button1.set_Text("Add Fruit");
        this.button1.add_Click(new System.EventHandler(this.button1_Click));
        this.button2.set_Location(new System.Drawing.Point(288, 64));
        this.button2.set_Size(new System.Drawing.Size(104, 32));
        this.button2.set_Text("Show Order");
        this.button2.add_Click(new System.EventHandler(this.button2_Click));
        this.button3.set_Location(new System.Drawing.Point(288, 104));
        this.button3.set_Size(new System.Drawing.Size(104, 32));
        this.button3.set_Text("Save Order");
        this.button3.add_Click(new System.EventHandler(this.button3_Click));
        this.set_ClientSize(new System.Drawing.Size(563, 273));
        this.get_Controls().AddRange(new System.Windows.Forms.Control[] { 
            this.listBox1, this.button3, this.button2, this.button1, 
            this.textBox1, this.checkedListBox1});
        this.set_Text("Fruit Order");
    } //InitializeComponent

    /** @attribute STAThread()
    public static void main(String[] args)
        Application.Run(new Form1());
    } //main

    // Adds the string if the text box has data in it.
    private void button1_Click(Object sender, System.EventArgs e)
        if (!textBox1.get_Text().Equals("")) {
            if (checkedListBox1.get_CheckedItems().Contains(textBox1.get_Text())
                == false) {
    } //button1_Click

    // Activates or deactivates the Add button.
    private void textBox1_TextChanged(Object sender, System.EventArgs e)
        if (textBox1.get_Text().Equals("")) {
        else {
    } //textBox1_TextChanged

    // Moves the checked items from the CheckedListBox to the listBox.
    private void button2_Click(Object sender, System.EventArgs e)
        for (int i = 0; i < checkedListBox1.get_CheckedItems().get_Count(); 
            i++) {
        if (listBox1.get_Items().get_Count() > 0) {
    } //button2_Click

    // Activates the move button if there are checked items.
    private void checkedListBox1_ItemCheck(Object sender, ItemCheckEventArgs e)
        if (e.get_NewValue().Equals(CheckState.Unchecked)) {
            if (checkedListBox1.get_CheckedItems().get_Count() == 1) {
        else {
    } //checkedListBox1_ItemCheck

    // Saves the items to a file.
    private void button3_Click(Object sender, System.EventArgs e)
        // Insert code to save a file.
        IEnumerator myEnumerator;
        myEnumerator = checkedListBox1.get_CheckedIndices().GetEnumerator();
        int y;
        while ((myEnumerator.MoveNext() != false)) {
            y = (int)(System.Convert.ToInt32(myEnumerator.get_Current()));
            checkedListBox1.SetItemChecked(y, false);
    } //button3_Click
} //Form1

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0