public class HelloWorld {

    public static void main(String[] args) {


        Set<Integer>set=new HashSet<>();//数据不会排序
        Set<Integer>treeset=new TreeSet<>();//数据会排序
        Random r=new Random();
        while (set.size()<10)
        {
            int num=r.nextInt(20)+1;
            set.add(num);
        }
        for(Integer i:set) {
            System.out.println(i);
        }
    }
}