randomAlphaNumericString method
Implementation
String randomAlphaNumericString(int length) {
if (length < 1) throw ArgumentError("length < 1: $length");
StringBuffer sb = StringBuffer();
for (int idx = 0; idx < length; ++idx)
sb.write(alphaNumeric[random.nextInt(alphaNumeric.length)]);
return sb.toString();
}