2019.2.26实用类随机数作业

1.

package com.demo1;

import java.util.Random;

public class Test2 {
    public static void main(String[] args) {
        Random ran = new Random();
        int index = 1;
        do {
            int a = ran.nextInt(7)+3;//随机生成0~7之间数字然后加3
            int b = ran.nextInt(1000000000);
            do {
                b = ran.nextInt(1000000000);
            }while(b<100000000);
            System.out.println("1"+a+b);
            index++;
        }while(index<10);
    }
}

输出：

2.

public static String getCode(int length) {
        String val = "";
        Random random = new Random();
        for (int i = 0; i < length; i++) {
            String charOrNum = random.nextInt(2) % 2 == 0 ? "char" : "num";
            // 输出字母还是数字
            if ("char".equalsIgnoreCase(charOrNum)) {
                // 输出是大写字母还是小写字母
                int temp = random.nextInt(2) % 2 == 0 ? 65 : 97;
                val += (char) (random.nextInt(26) + temp);
            } else if ("num".equalsIgnoreCase(charOrNum)) {
                val += String.valueOf(random.nextInt(10));
            }
        }
        return val;
    }

package com.demo1;

import java.util.Random;

public class Test3 {
    public static void main(String[] args) {
        Random ran = new Random();
        //定义一个数字num
        char num;
        //循环6次得到6个
        for(int i = 0;i<6;i++) {
            while(true) {
                num = (char)ran.nextInt();//强制转换为char类型
                //根据ASC码表定义取值范围
                if(num>47&&num<58||num>64&&num<91||num>96&&num<123) {
                    break;
                }
            }
            System.out.print(num);
        }

    }
}

输出：