title: Validate preferences. Android
body: <p>I have <code>PreferenceActivity</code> with 2 fields.</p>
  
  <ol>
  <li>A URL</li>
  <li>Time in seconds</li>
  </ol>
  
  <p>I need to validate the first one for a valid URL and the second for an integer value. How do I do it with standard means?</p>