CheckedListBox allowing only one item to be checked

Question

In my CheckedListBox app I want to allow only a single item to be checked.

I have these properties already set

checkOnClick = true;
SelectionMode = One;

Any advise will be appreciated

Infante

When the user clicks on the listbox, uncheck the other items. – Forgiven

would a grouping of radio buttons not suit things better? – Majewski

First google hit: social.msdn.microsoft.com/Forums/en-US/winforms/thread/… – Transcend

It seems CheckedListBox inherits SelectionMode from ListBox, but ignores that property. – Roadbed

@Roadbed Selection is different and checking is different. You can have something selected but not checked. – Infante

Answer 1

uncheck all other items in ItemCheck event as below :

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e) {
      for (int ix = 0; ix < checkedListBox1.Items.Count; ++ix)
        if (ix != e.Index) checkedListBox1.SetItemChecked(ix, false);
    }

Hesitation

Thanks, I thought there must have been a simple property that would do. – Infante

even simpler is radio buttons, customers are used to radiobuttons being only one choice and checkboxes being multiple choice, be very careful before you force changes on them like this – Biocellate

@Infante as RhysW said you are better off using radio button...but if you have to use checkboxes then this way would work.. – Hesitation

@Sam1 Surely that would have been better but in this case I am across an exceptional different scenario where this approach fits best. – Infante

@Infante as I said if you have to then there is no reason not to use it :) – Hesitation

Answer 2

the best way to do this is like this:

private void checkedListBox1_ItemCheck(object sender, ItemCheckEventArgs e)
{
    if (e.NewValue == CheckState.Checked && checkedListBox1.CheckedItems.Count > 0)
    {
        checkedListBox1.ItemCheck -= checkedListBox1_ItemCheck;
        checkedListBox1.SetItemChecked(checkedListBox1.CheckedIndices[0], false);
        checkedListBox1.ItemCheck += checkedListBox1_ItemCheck;
    }
}

no looping is always better.

Hasheem

Answer 3

We can also do this by checkedListBox1_SelectedIndexChanged Event.

private void checkedListBox1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int idx = checkedListBox1.SelectedIndex;
        for(int i=0;i<checkedListBox1.Items.Count;i++)
        {
            if(i != idx)
            {
                checkedListBox1.SetItemChecked(i, false);
            }
        }
            
    }

Farnese

Answer 4

Updated to Visual 2019

protected void chb_list_SelectedIndexChanged(object sender, EventArgs e)
        {
            int idx = chb_list.SelectedIndex;
            for (int i = 0; i < chb_list.Items.Count; i++)
            {
                if (i != idx)
                {
                    chb_list.Items[i].Selected = false;
                }
            }
        }

Riegel