"Problem with URL:\n" + ex.getMessage(),
"Couldn't read from URL:\n" + u,
  protected void setInstancesFromURL(URL u) {    try {      Reader r = new BufferedReader(new InputStreamReader(u.openStream()));      setInstances(new Instances(r));      r.close();    } catch (Exception ex) {      JOptionPane.showMessageDialog(this,				    "Problem with URL:\n"				    + ex.getMessage(),				    "Load Instances",				    JOptionPane.ERROR_MESSAGE);    }  }