How to get Selected value of a DropDown in Silverlight

Here I am referring to a combobox and having primitive or complex types. If so we can get the selected item value from the SelectedItem Property.

private void getSelectedValue()
  {
    foreach (object obj in radCmb.Items)
      {
          MessageBox.Show(radCmb.SelectedItem.ToString());
           return;
        }
   }
And then you can call this method in a eventHanlder, i am calling this on button click event of my page. 

private void radButton1_Click(object sender, RoutedEventArgs e)
        {getSelectedValue();}