title: Prevent adding duplicate items on ListView
body: <p>Could someone give me LINQ code to avoid allowing duplicate items when adding new items into <code>ListView</code>?</p>
  <p>Here's my current code for adding items from clipboard with regex.</p>
  <pre><code>List&lt;string&gt; uri = new List&lt;string&gt;();
  string URLPattern = cbRegEx.Text;
  string cb = Clipboard.GetText();
  
  uri.Clear();
  MatchCollection mc = Regex.Matches(cb, URLPattern, RegexOptions.IgnoreCase);
  foreach (Match m in mc)
  {
      uri.Add(m.Value);
  }
  
  LV_Url.BeginUpdate();
  foreach (var Uri in uri)
  {
      ListViewItem lv = new ListViewItem();
      lv.Text = (LV_Url.Items.Count + 1).ToString();
      lv.SubItems.Add(GetUrlFileName(Uri));
      lv.SubItems.Add(Uri);
      LV_Url.Items.Add(lv);
      LV_Url.AutoResizeColumn(1, ColumnHeaderAutoResizeStyle.ColumnContent);
  }
  LV_Url.EndUpdate();
  </code></pre>