import 'dart:math'; class RandomUtil { static const _characters = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'; static String randomString(int length) { Random random = Random(); return String.fromCharCodes(Iterable.generate( length, (_) => _characters.codeUnitAt(random.nextInt(_characters.length)), )); } }