c# - Update SelectedItem on ListView -

i have listview displays multiple rows of listviewitems. user able edit row clicking edit button opens form displaying selected row , data within it. problem having cannot seem update listviewitem on parent form when press update button. code using keeps throwing exception message "an unhandled exception of type 'system.nullreferenceexception' occurred in todolist.exe". have tried different approaches updating selected item cannot seem working code.

this code using on form displays selected row, button1 "update row" button should update listview.

private void button1_click(object sender, eventargs e)     {         form1 form1 = (form1)this.owner;          int = 0;         listviewitem item = form1.listview1.selecteditems[i];         textbox1.text = item.subitems[0].text;         richtextbox1.text = item.subitems[1].text;         combobox1.text = item.subitems[2].text;         datetimepicker1.text = item.subitems[3].text;          this.close();     } 

to make form owned form, assign owner property reference form owner.

https://msdn.microsoft.com/en-us/library/system.windows.forms.form.owner%28v=vs.110%29.aspx

you need set owner property first