模拟注册--登录--幸运抽奖---全过程（一步步实现）

System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");

    Scanner in = new Scanner(System.in);

        System.out.print("请选择菜单：");

        int sc = in.nextInt();
         switch (sc) {
            case 1:
                System.out.println("抽奖富翁系统----->注册");
            break;
            case 2:
                System.out.println("抽奖富翁系统----->登录");

                break;
            case 3:
                System.out.println("抽奖富翁系统----->抽奖");

                break;

            default:
                System.out.println("输入错误，请重新输入：");
                break;
            }

public static void main(String[] args) {
System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");

    Scanner in = new Scanner(System.in);

    String answer="";
    do {
        System.out.print("请选择菜单：");
        int sc = in.nextInt();
         switch (sc) {
            case 1:
                System.out.println("抽奖富翁系统----->注册");
                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;
            case 2:
                System.out.println("抽奖富翁系统----->登录");
                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;
            case 3:
                System.out.println("抽奖富翁系统----->抽奖");
                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;

            default:
                System.out.println("输入错误，请重新输入：");
                break;
            }

    } while ( answer.equals("Y"));
    System.out.println("程序结束，退出程序。");
}

System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");

    Scanner in = new Scanner(System.in);

    String answer="";
    do {
        System.out.print("请选择菜单：");
        int sc = in.nextInt();
         switch (sc) {
            case 1:
                System.out.println("抽奖富翁系统----->注册");

                System.out.println("输入用户名:");
                String name=in.next();

                System.out.println("输入密码:");
                int password=in.nextInt();

                int card=   (int)(Math.random()*9000+1000);
                System.out.println("card:"+card);

                System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
                System.out.println("会员卡号\t"+"会员名\t"+"密码");
                System.out.println(card+"\t"+name+"\t"+password);

                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;
            case 2:
                System.out.println("抽奖富翁系统----->登录");
                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;
            case 3:
                System.out.println("抽奖富翁系统----->抽奖");
                System.out.println("是否选择继续:Y/N");
                answer=in.next();
                continue;

            default:
                System.out.println("输入错误，请重新输入：");
                break;
            }

    } while ( answer.equals("Y"));
    System.out.println("程序结束，退出程序。");

-----------------

System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");

    Scanner in = new Scanner(System.in);

    String answer = "";
    int password = 0;
    String name = "";
    int card = 0;
    do {
        System.out.print("请选择菜单：");
        int sc = in.nextInt();
        switch (sc) {
        case 1:
            System.out.println("抽奖富翁系统----->注册");

            System.out.println("输入用户名:");
            name = in.next();

            System.out.println("输入密码:");
            password = in.nextInt();

            card = (int) (Math.random() * 9000 + 1000);
            System.out.println("card:" + card);

            System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
            System.out.println("会员卡号\t" + "会员名\t" + "密码");
            System.out.println(card + "\t" + name + "\t" + password);

            System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;
        case 2:
            System.out.println("抽奖富翁系统----->登录");

                for (int i = 0; i < 3; i++) {

                    System.out.println("请输入你的会员卡号");
                    int card1 = in.nextInt();

                    System.out.println("请输入你的会员会员名");
                    String name1 = in.next();

                    System.out.println("请输入你的会员名密码");
                    int password1 = in.nextInt();
                    if (card1 == card && name1.equals(name) && password1 == password) {
                        System.out.println("登录成功");
                        break;
                    }

                    if (card1 != card || !name1.equals(name) || password1 != password) {
                        System.err.println("输入错误，请重新输入，你还有：" + (2 - i) + "次机会");
                        continue;
                    }
                }

        System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;
        case 3:
            System.out.println("抽奖富翁系统----->抽奖");

            System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;

        default:
            System.out.println("输入错误，请重新输入：");
            break;
        }

    } while (answer.equals("Y"));
    System.out.println("程序结束，退出程序。");

}

System.out.println("欢迎使用抽奖富翁系统");
System.out.println("\t1.注册");
System.out.println("\t2.登录");
System.out.println("\t3.抽奖");
System.out.println("***");

    Scanner in = new Scanner(System.in);

    String answer = "";
    int password = 0;
    String name = "";
    int card = 0;
    do {
        System.out.print("请选择菜单：");
        int sc = in.nextInt();
        switch (sc) {
        case 1:
            System.out.println("抽奖富翁系统----->注册");

            System.out.println("输入用户名:");
            name = in.next();

            System.out.println("输入密码:");
            password = in.nextInt();

            card = (int) (Math.random() * 9000 + 1000);
            System.out.println("card:" + card);

            System.out.println("注册成功，请记住你的会员卡号，会员名，密码");
            System.out.println("会员卡号\t" + "会员名\t" + "密码");
            System.out.println(card + "\t" + name + "\t" + password);

            System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;
        case 2:
            System.out.println("抽奖富翁系统----->登录");

            for (int i = 0; i < 3; i++) {

                System.out.println("请输入你的会员卡号");
                int card1 = in.nextInt();

                System.out.println("请输入你的会员会员名");
                String name1 = in.next();

                System.out.println("请输入你的会员名密码");
                int password1 = in.nextInt();
                if (card1 == card && name1.equals(name) && password1 == password) {
                    System.out.println("登录成功");
                    break;
                }

                if (card1 != card || !name1.equals(name) || password1 != password) {
                    System.err.println("输入错误，请重新输入，你还有：" + (2 - i) + "次机会");
                    continue;
                }
            }

            System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;
        case 3:
            System.out.println("抽奖富翁系统----->抽奖");

            for (int k = 0; k < 4; k++) {
                int q=(int)(Math.random()*9000+1000);
                System.out.println("本期的幸运数组是："+q);
                if (q==card) {
                    System.out.println("恭喜你是幸运客户，");
                    break;
                }
                else{
                    System.out.println("你不是幸运客户，");
                    continue;
                }
            }

            System.out.println("是否选择继续:Y/N");
            answer = in.next();
            continue;

        default:
            System.out.println("输入错误，请重新输入：");
            break;
        }

    } while (answer.equals("Y"));
    System.out.println("程序结束，退出程序。");

到了这里本该结束的，但是有一个bug。抽奖功能的实现的一个前提是登陆成功，登录的前提是注册成功。不然直接选择菜单3.而没有经过1和2.就无法抽奖。弄了一个下午，代码大修，才算修改完善。

但是里面还有很多重复，System.out.println("是否选择继续:Y/N");
answer = in.next();
if (answer.equals("Y")) {
continue;
}
else {
System.out.println("程序结束，退出程序。");
return;
这是一个问题。

break；continue；return。用的总是感觉不对。这是第二个问题。

第三个问题。while（true）无线循环。外面无法再写入代码？这个是个问题吗？要是不是的话？岂不是复杂代码无法应用无限循环了。

希望大家能帮我解惑，谢谢。