随机生成20个手机号，待完善

 1 package com.homework;
 2 
 3 import java.util.HashSet;
 4 import java.util.Set;
 5 
 6 public class RandomPhone {
 7     //初始化手机前三位
 8     static String[] First = {"139","138","137","136","135","134","159","158","157", 
 9             "150","151","152","188","130","131","132","156","135","133","153","189"};
10     //手机号唯一 无序
11     static Set<String> phoneSet = new HashSet<String>();
12     //static Set<String> phoneSet = new HashSet<String>();
13     
14     //getNumber方法来获得数字
15     public static int getNumber(int start,int end) {
16         int sum = (int)(Math.random()*(end+1-start)+start);
17         return sum;
18     }
19     public static void main(String[] args) {
20         String first = null;
21         String second = null;
22         String third = null;
23         
24         
25         
26         for(;phoneSet.size() <20;) {
27             //手机号前三位
28             int index  = getNumber(0,First.length-1);
29             first  = First[index];
30             // substring 的作用是从指定位置开始字符串
31             //生成手机剩下的8位号码
32             second = String.valueOf(getNumber(0,99999)+100000);
33             third = String.valueOf(getNumber(0,999)+1000);
34 //            second = String.valueOf(getNumber(0,99999)+100000).substring(0);
35 //            third = String.valueOf(getNumber(0,999)+1000).substring(0);
36             String ch = first+second+third;
37             phoneSet.add(ch);
38         }
39         int i = 0;
40         for(String sc :phoneSet) {
41             System.out.println("第"+(++i)+"的手机号是"+sc);
42         }
43     }
44 }