Asp.net vb.net
Can I add check box in radComboBox, if Yes how to add
And how to collect the checked items

First of all I am not sure what you are trying to achieve on this and your requirement...
The basic purpose of checkboxes and radiolist are different the former being for selection of any of those and the later one for only one among many...
Hence, this is not possible on the radiocombobox to have checkbox...

// Get Values from CheckBoxList

String values = "";

for (int i=0; i< cbl.Items.Count; i++)

{

        if(cbl.Items[i].Selected)

        {

                values += cbl.Items[i].Value + ",";

        }

}

                        

values = values.TrimEnd(',');

checkbox ch;
int count;
for(int i=0;i<dggrid.items.count;i++)
{
 ch = dggrid.items[i].findcontrols("checkItem");
if(ch == checked)
{
  count =count+1;
}
}
respone.write(count);
 
checkItem --->Checkbox id