Java获取随机数

import java.util.Random;

public class randomDemo {

    public static void main(String[]args){
        randomDemo r=new randomDemo();
        System.out.println(r.randomCode());

    }
    public static String randomCode() {
        StringBuilder str = new StringBuilder("");
        Random random = new Random();
        for (int i = 0; i < 8; i++) {
          str.append(random.nextInt(10));//i 为获取多少位随机数
        }
        return str.toString();
    }
}