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CheckedListBox.CheckedItemCollection Class

Encapsulates the collection of checked items, including items in an indeterminate state, in a CheckedListBox control.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)

public class CheckedItemCollection : IList, ICollection, IEnumerable
public class CheckedItemCollection implements IList, ICollection, 
	IEnumerable
public class CheckedItemCollection implements IList, ICollection, 
	IEnumerable
Not applicable.

The checked items collection is a subset of all items in the CheckedListBox control; it contains only those items that are in a checked or indeterminate state.

The following table is 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

Based on the previous example, the following table shows the indexed collection of the checked items.

Index

Item

0

object 2

1

object 4

2

object 5

The CheckedListBox class has two members that allow you to access the stored indexes, the Item property and the IndexOf method.

Based on the previous example, a call to the Item property with a parameter value of 1 returns object 4. A call to IndexOf with a parameter of object 4 returns a value of 1.

The following example enumerates the checked items in the CheckedListBox.CheckedIndexCollection to see what check state an item is in. The example demonstrates using the GetItemCheckState method to set the check state of an item. The example also demonstrates using the CheckedIndices property to get the CheckedListBox.CheckedIndexCollection, and the CheckedItems property to get the CheckedListBox.CheckedItemCollection.

The first loop uses the GetItemCheckState method to get the CheckState of each checked item, given the index of the item. The second loop also uses GetItemCheckState, but uses the ListBox.ObjectCollection.IndexOf method to retrieve the index for the item.

private void WhatIsChecked_Click(object sender, System.EventArgs e) {
    // Display in a message box all the items that are checked.

    // First show the index and check state of all selected items.
    foreach(int indexChecked in checkedListBox1.CheckedIndices) {
        // The indexChecked variable contains the index of the item.
        MessageBox.Show("Index#: " + indexChecked.ToString() + ", is checked. Checked state is:" +
                        checkedListBox1.GetItemCheckState(indexChecked).ToString() + ".");
    }

    // Next show the object title and check state for each item selected.
    foreach(object itemChecked in checkedListBox1.CheckedItems) {

        // Use the IndexOf method to get the index of an item.
        MessageBox.Show("Item with title: \"" + itemChecked.ToString() + 
                        "\", is checked. Checked state is: " + 
                        checkedListBox1.GetItemCheckState(checkedListBox1.Items.IndexOf(itemChecked)).ToString() + ".");
    }

}

private void whatIsChecked_Click(Object sender, System.EventArgs e)
{
    // Display in a message box all the items that are checked.
    // First show the index and check state of all selected items.
    IEnumerator objEnum = checkedListBox1.get_CheckedIndices().
        GetEnumerator();

    while (objEnum.MoveNext()) {
        int indexChecked = (int)(Int32)(objEnum.get_Current());

        // The indexChecked variable contains the index of the item.
        MessageBox.Show("Index#: " + (Int32)indexChecked 
            + ", is checked. Checked state is:" 
            + checkedListBox1.GetItemCheckState(indexChecked).ToString() 
            + ".");
    }

    // Next show the object title and check state for each item selected.
    for (int iCtr = 0; 
        iCtr < checkedListBox1.get_CheckedItems().get_Count(); 
        iCtr++) {
        Object itemChecked = 
            checkedListBox1.get_CheckedItems().get_Item(iCtr);

        // Use the IndexOf method to get the index of an item.
        MessageBox.Show("Item with title: \"" + itemChecked.ToString() 
            + "\", is checked. Checked state is: " 
            + checkedListBox1.GetItemCheckState(
            checkedListBox1.get_Items().IndexOf(itemChecked)).ToString() 
            + ".");
    }
} //whatIsChecked_Click

System.Object
  System.Windows.Forms.CheckedListBox.CheckedItemCollection

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 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

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