randomString function Null safety

dynamic randomString(
  1. {int len = 10,
  2. String charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@#\$%^&*()_+'}
)

Implementation

randomString({int len = 10, String charSet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@#\$%^&*()_+'}) {
  var randomString = '';
  for (var i = 0; i < len; i++) {
    var randomPoz = (Math.Random().nextInt(charSet.length - 1)).floor();
    randomString += charSet.substring(randomPoz, randomPoz + 1);
  }
  return randomString + Timeline.now.toString();
}