title: Why does my list reset when I press a button?
body: <p>I have a page where a instructor inserts a student's id into a text box and then submits it. It should then come up with a list of all the students that have been added. But every time the submit button is pressed, the list gets cleared and only the last student added is displayed.</p>
  
  <pre><code>public Service1Client ws = new Service1Client();
  public string adress;
  public List&lt;ServiceReference1.User&gt; lu;
  
  protected void Page_Load(object sender, EventArgs e)
  {
      if (lu==null)
          lu= new List&lt;ServiceReference1.User&gt;();
  }
  
  protected void Button1_Click(object sender, EventArgs e)
  {
      ServiceReference1.User u= new ServiceReference1.User();
      u = ws.ShowUser(int.Parse(TextBox2.Text));
  
      if (!IsContained(u))
      {
          lu.Add(u);
          TextBox1.Text += u.FirstName;
      }
  }
  </code></pre>
  
  <p>Is there a way to solve this? Or must I send the information to the page via a query string?</p>