title: Check if list view contain item
body: <p>i have a listview with 3 columns (id , name, author), i use this method to add row:</p>
  
  <pre><code>     public void addToLv(Book book)
      {
  
          //TODO: Verifier si l'item existe avant d'ajouter
          ListViewItem lvi1 = new ListViewItem(book.id.ToString());
          lvi1.Text = book.id.ToString();
          lvi1.SubItems.Add(book.name);
          lvi1.SubItems.Add(carte.author);
  
          listView1.Items.Add(lvi1);
  
      }
  </code></pre>
  
  <p>Now i wan't to check if book exists before i insert the new one to avoid duplicate element, i try this code but it'S not working
  i have use this line but it's not working:</p>
  
  <pre><code>  (listView1.Items.ContainsKey(book.id))
           {
        listView1.Items.Add(lvi1);
           }
  </code></pre>
  
  <p>Can you help me please? thank you</p>