p.add(Box.createHorizontalGlue());
final JOptionPane op = new JOptionPane(p, JOptionPane.PLAIN_MESSAGE, JOptionPane.OK_CANCEL_OPTION);
op.setWantsInput(true);
JDialog dlg = op.createDialog(this, prompt);
dlg.show();
dlg.dispose();
Object value = op.getInputValue();
if (value == JOptionPane.UNINITIALIZED_VALUE) {
return null;
}
String str = (String) value;