JAVA学习笔记（六）

简单抽奖系统，用random定义1~100个随机数，随机产生一二三等奖。效果图如下：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;
public class xitong {
     private ArrayList<Integer> list;

    public ArrayList<Integer> addPerson() {
        // TODO Auto-generated constructor stub
    if(list == null){
        list = new ArrayList<Integer>();
        for(int i = 1;i <= 100;i++){   
            list.add(i);
        }
    }
    Collections.shuffle(list);
    return(list);
}

public void choujiang(){
    Random r = new Random();  //定义1~100个随机数
    int a = r.nextInt(100);
    System.out.println("一等奖：" + list.get(a) + "号");
    list.remove(a);
    for(int j = 1; j <= 2;j++){
        a = r.nextInt(100);
        System.out.println("二等奖：" + list.get(a) + "号");
        list.remove(a);    
    }
        for(int k = 1; k <= 3;k++){
            a = r.nextInt(100);
            System.out.println("三等奖：" + list.get(a) + "号");
            list.remove(a);    
            System.out.println("恭喜你中奖了！");
        }    
        System.out.println("谢谢参与!");
    } 
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        xitong b = new xitong();
        b.addPerson();
        b.choujiang();
    }
}