import 'dart:math'; void main() { print(getRandomString(5)); // 5GKjb print(getRandomString(10)); // LZrJOTBNGA print(getRandomString(15)); // PqokAO1BQBHyJVK } const _chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz1234567890'; Random _rnd = Random(); String getRandomString(int length) => String.fromCharCodes(Iterable.generate( length, (_) => _chars.codeUnitAt(_rnd.nextInt(_chars.length))));