java入门 -- 随机数类

使用随机数类产生验证码

import java.util.Random;

/*

* 验证码

*/

public class Demo16 {

public static void main(String[] args) {

char[] arr = {'我','是','a','b','中','c','e','g'};

StringBuilder sb = new StringBuilder();

Random rd = new Random();

int index = 0;

int len = arr.length;

for(int i=0; i<4; i++)

{

index = rd.nextInt(len);

sb.append(arr[index]);

}

//输出验证码

System.out.println(sb);

}

}