title: C# how to refresh serial port in c#
body: <p>i want to make my application can refresh serial port in c#. when list of port(In ComboBox) is empty and i hit button <code>refresh</code>, it's work perfectly and show the list of active port. but if i disconnected the <code>Serial Port</code> and i hit <code>refresh</code> button, actually it's must make the list of port(In Combobox) is empty because the serial port is disconnected. So how to make when i hit <code>refresh</code> button and the condition is disconnected, we make all of port list(in Combobox ) is empty ?</p>
  
  <p>this is my code in refresh button:</p>
  
  <pre><code>private void button2_Click_2(object sender, EventArgs e)
  {
      if(String.IsNullOrEmpty(cboPort.Text))
      {
          comm.SetPortNameValues(cboPort);
  
          for (int i = 0; i &lt; cboPort.Items.Count; i++)
          {
              string value = cboPort.GetItemText(cboPort.Items[i]);
  
              if (String.IsNullOrEmpty(value))
              {
                  string a = cboPort.SelectedIndex.ToString();
                  return;
              }
              else
              {
                  cboPort.SelectedIndex = 0;
              }
          }
       }
       else if ((cboPort.Text) != " " &amp;&amp; cboPort.SelectedIndex == -1)
       {
             cboPort.Text = " ";
             return;
       }
  }
  </code></pre>
  
  <p>this is my code in setportnamevalues :</p>
  
  <pre><code>    public void SetPortNameValues(object obj)
      {
          foreach (string str in SerialPort.GetPortNames())
          {
               ((ComboBox)obj).Items.Add(str);   
          }
      }
  </code></pre>
  
  <p>my expetation is :</p>
  
  <p><code>1. i connect serial port 
  2. i run my app 
  3. i disconnect serial port
  4. i hit refresh
  5. final result is port list empty in combobox</code></p>
  
  <p>thanks for helping and responses, i am still new in c#. Greetings! </p>