java随机数的产生

1. import java.util.*; 
2.(A) public class Test
       { public static void main(String[] args)
         { 
         //生成 [0-n) 个不重复的随机数  st 用来保存这些随机数 
         ArrayList list = new ArrayList();  
         int n = 10; 
         Random rand = new Random();          
         boolean[] bool = new boolean[n];  
         int num =0;   
         for (int i = 0; i<n; i++)
                 { 
               do{//如果产生的数相同继续循环 
                 num = rand.nextInt(n);     
             }while(bool[num]);  
             bool[num] =true;  
             list.add(num);
         } 
         System.out.println (list);     
    }
(B)        
    public class Test 
 { 
    public static void main(String[] args) 
     { 
      &