Java(六)——抽獎系統

 總體思路:

      將編號加入ArrayList動態數組中，利用集合的靜態方法Collections.shuffle() 亂序集合中的元素從而獲得隨機數，remove刪除已抽編號

 代碼如下:

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

public class raffle {

    private ArrayList<Integer> list;
    
    private void deal(){
        //向list容器中順序添加指定數量num的整數
        if (list==null) {
            list = new ArrayList<Integer>();
            for (int i = 1; i < 1000; i++) {
                list.add(i);
            } 
        }                
        //打亂list中元素順序
        Collections.shuffle(list);                
    }
    
    //抽獎的方法：抽出指定數量的獎項
    public void draw(){
        Random rdom = new Random();
        
        int index = rdom.nextInt(list.size());
        System.out.println("一等獎："+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("二等獎："+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("三等獎："+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();

    }    
} 

 運行結果: