CheckedListBox.ObjectCollection Class

The collection is accessed from the parent control, CheckedListBox, by the Items property. To create a collection of objects to display in the CheckedListBox control, you can add or remove the items individually by using the Add and Remove methods.

The following example enumerates the items in the CheckedListBox and checks every other item in the list. The example demonstrates using the Items property to get the CheckedListBox.ObjectCollection to get the Count of items.

The example also demonstrates using the SetItemCheckState and SetItemChecked methods to set the check state of an item. For every other item that is to be checked, SetItemCheckState is called to set the CheckState to Indeterminate, while SetItemChecked is called on the other item to set the checked state to Checked.

private void CheckEveryOther_Click(object sender, System.EventArgs e) {
    // Cycle through every item and check every other.

    // Set flag to true to know when this code is being executed. Used in the ItemCheck
    // event handler.
    insideCheckEveryOther = true;

    for (int i = 0; i < checkedListBox1.Items.Count; i++) {
        // For every other item in the list, set as checked.
        if ((i % 2) == 0) {
            // But for each other item that is to be checked, set as being in an
            // indeterminate checked state.
            if ((i % 4) == 0)
                checkedListBox1.SetItemCheckState(i, CheckState.Indeterminate);
            else
                checkedListBox1.SetItemChecked(i, true);
        }
    }        

    insideCheckEveryOther = false;
}

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference