随机数唯一性算法？
public static void main(String[] args) {
List
HashSet
for(int i=0; i<100000; i++) {
int hashCode = UUID.randomUUID().toString().replaceAll("-", "").hashCode();
hashCode = hashCode < 0 ? hashCode * -1 : hashCode;
list.add(hashCode);
}
set.addAll(list);
System.out.println(list.size());
System.out.println(set.size());
System.out.println(list.size()-set.size());
}
