kHandler</code> might choose to sequentially ask
 the user for login and password, if it implements these <code>Callback</code>
 s, whereas a GUI-based one might open a single dialog window for both
 values. If a <code>CallbackHandler</code> is not able to handle a specific
 <code>Callback</code>, it needs to throw an
 <code><a href="../../../../../reference/javax/security/auth/callback/UnsupportedCallbackException.html">UnsupportedCallbackException</a></code>.</p></div>
  <div class="jd-tagdata">
      <h5