Move all sub items in listview details to my main form listview C#

Question

how do i move all of the items from my listview (listview2) to my main form listview (lv_Collection)?

public Main_Form mainref;
private void btnOK_Click(object sender, EventArgs e)
        {
            ListViewItem itemClone = new ListViewItem();
            ListView.ListViewItemCollection col1 = listView2.Items;
            foreach (ListViewItem item in col1)
            {     
                itemClone = item.Clone() as ListViewItem;
                listView2.Items.Remove(item);
                mainref.lv_Collection.Items.Add(itemClone);
                //mainref.Refresh();
            }
            this.Close();
        }

I got an error on this code " mainref.lv_Collection.Items.Add(itemClone); "

My main form code

Collection_Forms.Collection_Accredited_Select frm = new Collection_Forms.Collection_Accredited_Select();
                    frm.ShowDialog();
                    frm.mainref = this;

Answer 1

No need to clone them if you want to move them all:

private void btnOK_Click(object sender, EventArgs e)
{
    int count = listView1.Items.Count;
    for (int i = 0; i < count; i++)
    {
        ListViewItem lvi = listView1.Items[listView1.Items.Count - 1];
        listView1.Items.Remove(lvi);
        listView2.Items.Add(lvi);
    }
}

If you want to move only some items best collect them in a List<ListViewItem> and then loop over the list.

I assume that you really want to move the complete items, not just their subitems?

Also note that you are not allowed to modify the collection you are iterating over in a foreach loop..