转自CSDN----"双色球随机摇号"

import java.util.*;
public class doublecolourball {
 
 
     public static void main(String[] args) { 
  
  
         System.out.println(Arrays.toString(randomBall()));//Arrays在java.util.*,里面 
     } 
     public static String[] randomBall(){ 
         String[] pool={"01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31","32","33"}; 
         String[] balls=new String[7];//字符串型，因球是01，02，03......33 
         boolean[] flags=new boolean[33];//数组默认元素值为“0”，布尔型为false 
         int i=0; 
         Random r=new Random();//用到类库中函数Random 
         while(true){ 
             int index=r.nextInt(33);//随机的33个，指的是[0,33),即索引或下标从0到32，不包括33，刚好33个 
             if(flags[index]==true){ 
                 continue;//表示这号被选过了，跳过 
             } 
             balls[i++] = pool[index];//把没选过的存放到balls数组中，i 
             flags[index] = true; if(i==6){
                 break;  //当找到6个时候停止      
             } 
         } 
         Arrays.sort(balls,0,5);//Arrays.sort(canshu)系统对数组的排序算法,0,5,表示排序0-5， 
         //int index=r.nextInt(16);//同上，[0,16) 
         //String blueBall=pool[index];//蓝球就1个字符，所以只需随机一个放进blueBall中 
         //balls[6]=blueBall; 
         balls[6] = pool[r.nextInt(16)];//这是对上面三条的简化，把蓝球buleBall放入到balls中第7个，即下标6那 
         return balls; 
          
     } 
      
      
 } 
 //下面是对于flag[index]==false帮助理解 
 //(flag[index]==false)==true;(falg[index]==true)==false 
 //if(true)== if(!flag[index])==if((flag[index]==false)) 
 //if(false)==if(flag[index]) == if(falg[index]==true)