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: