JAVA幸运抽奖

import java.util.Scanner;
public class Di8Zhang2 {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String user="";
String password="";
boolean iszhuce=false;
boolean islogin =false;
int cardNum=-1;
for(String choice = "y";choice.equals("y");choice = in.next()){
System.out.println("*****欢迎进入奖客富翁系统*****");
System.out.println("\t1.注册");
System.out.println("\t2.登陆");
System.out.println("\t3.抽奖");
System.out.println("************************");
System.out.print("请选择,菜单:");
int y = in.nextInt();
switch (y) {
case 1:
System.out.println("[奖客登陆系统>注册");
System.out.println("请输入用户名：");
user=in.next();
System.out.println("请输入密码：");
password=in.next();
cardNum=(int)(Math.random()*(9999-1000)+1000);
System.out.println("注册成功，请记住你的会员卡号");
System.out.println("用户名\t密码\t卡号");
System.out.println(user+"\t"+password+"\t"+cardNum);
iszhuce=true;
break;
case 2:
if (iszhuce==true){
for(int i= 0;i<3;i++){
System.out.println("[奖客登陆系统>登录");
System.out.println("请输入用户名：");
String user1=in.next();
System.out.println("请输入密码：");
String password1=in.next();
if(user1.equals(user)&&password.equals(password1)){
System.out.println("欢迎您，"+user1);
islogin = true;
break;
}else if(i!=2){
System.out.println("你还有"+(2-i)+"次机会");
}else{
System.out.println("次数已到，请你重新注册");
iszhuce = false;
}
}
}else{
System.out.println("请先注册");
}
break;
case 3:
System.out.println("[奖客登陆系统>抽奖");
if(islogin){
System.out.println("请输入卡号：");
int cardNo = in.nextInt();
int[] nums = new int[5];
if(cardNo ==cardNum){
for(int i = 0;i<nums.length;i++){
nums[i] = (int)(Math.random()*(9999-1000)+1000);
System.out.print(nums[i]+"\t");
}
boolean isZhongJiang = false;
for(int i=0;i<nums.length;i++){
if(nums[i]==cardNo){
System.out.println("欢迎中奖");
isZhongJiang = true;
}
}
if(!isZhongJiang){
System.out.println("没有中奖，下次会再来");
}
}
}else{
System.out.println("请你登录");
}
break;
default:
System.out.println("输入错误，请你重新输入");
}
System.out.println("你还继续吗？(y/n)");
}
System.out.println("系统退出，谢谢使用！");
}
}。