import 'dart:math'; class ICRandomUtil { static int getRandomUserId(List ids,int id) { while (ids.contains(id)) { getRandomUserId(ids,Random().nextInt(1000)); } return id; } static int getRandomUserIndex(List ids) { if (!ids.contains(1)) { return 1; } if (!ids.contains(2)) { return 2; } if (!ids.contains(3)) { return 3; } return 4; } }