Java(六)——抽奖系统

 总体思路:

将编号加入ArrayList动态数组中，利用集合的静态方法Collections.shuffle() 乱序集合中的元素从而获得随机数，remove删除已抽编号

 代码如下:

 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Random;

 public class raffle {

     private ArrayList<Integer> list;

     private void deal(){
         //向list容器中顺序添加指定数量num的整数
         if (list==null) {
             list = new ArrayList<Integer>();
             for (int i = 1; i < 1000; i++) {
                 list.add(i);
             }
         }
         //打乱list中元素顺序
         Collections.shuffle(list);
     }

     //抽奖的方法：抽出指定数量的奖项
     public void draw(){
         Random rdom = new Random();

         int index = rdom.nextInt(list.size());
         System.out.println("一等奖："+list.get(index));
         list.remove(index);
         Collections.shuffle(list);

         for (int i = 0; i < 2; i++) {
             int index2 = rdom.nextInt(list.size());
             System.out.println("二等奖："+list .get(index2));
             list.remove(index2);
         }
         Collections.shuffle(list);

         for (int i = 0; i < 3; i++) {
             int index3 = rdom.nextInt(list.size());
             System.out.println("三等奖："+list .get(index3));
             list.remove(index3);
         }
         Collections.shuffle(list);
     }

     public static void main(String[] args) {
         // TODO Auto-generated method stub
         raffle rf = new raffle();
         rf.deal();
         rf.draw();

     }
 } 

 运行结果: