Java computer examination purposes

1, generates a random digit, each digit will not be repeated.

. 1  Package com.cloud.stagging.lhcloudzuul;
 2  
. 3  Import java.util.Random;
 . 4  
. 5  / ** 
. 6  *. 1, generates a random digit, each digit will not be repeated.
. 7   * / 
. 8  public  class demo001image {
 . 9  
10      public  static  void main (String [] args) {
 . 11          generateNum ();
 12 is      }
 13 is  
14      Private  static  void generateNum () {
 15          the Random Random = new new the Random ();
 16          int[] arr = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
17         StringBuffer stringBuffer = new StringBuffer();
18         int tmp = 0;
19         while (stringBuffer.length() < 4) {
20             tmp = random.nextInt(10);//0-9的随机数
21             if (arr[tmp] == 0) {
22                 stringBuffer.append(tmp);
23                 arr[tmp] = 1;
24             }
25         }
26         System.out.println(stringBuffer);
27 
28     }
29 }