java - 如何发起重试 for 循环

Question

初学者，我正在创建一个非常简单的“登录”样式程序，目前我使用 if 语句来查看用户输入的内容是否与我已经声明的内容相匹配，如果他们正确，他们会得到一个“已登录”消息，如果没有则程序终止。

但是，我希望用户在终止之前最多可以尝试 3 次来获取正确的凭据。我该如何去做呢？

List<String> usernames = accessClass.setUsernames();
    List<String> passwords = accessClass.setPasswords();

    System.out.print("Please enter your username: ");

    user1 = wordScan.next();


    if(usernames.contains(user1)){

        System.out.print("Now enter your password: ");

        pass1=wordScan.next();

        if(passwords.contains(pass1)){

            System.out.println("Logged in.");
            System.out.println("Your username is "+user1);

            random.setSeed(System.currentTimeMillis());
            numGen = random.nextInt(899999)+100000;

            System.out.println("Your access code is: "+numGen);
        }
    }else{

        System.out.println("Invalid Username... Terminating.");
        System.exit(0);
    }

    wordScan.close();

}

非常感谢

Answer 1

我也会使用这样的循环:

    List<String> usernames = accessClass.setUsernames();
    List<String> passwords = accessClass.setPasswords();

    while(attempts > 0 && !loggedIn) {

        System.out.print("Please enter your username: ");

        user1 = wordScan.next();
        int attempts = 3;
        boolean loggedIn = false;

        attempts = attempts -1;
        if(usernames.contains(user1)){

            System.out.print("Now enter your password: ");

            pass1=wordScan.next();

            if(passwords.contains(pass1)){

                System.out.println("Logged in.");
                System.out.println("Your username is "+user1);
                loggedIn = true;
                random.setSeed(System.currentTimeMillis());
                numGen = random.nextInt(899999)+100000;

                System.out.println("Your access code is: "+numGen);
            }
        }
    }

    if(!loggedIn) {
        System.out.println("Invalid Username or password... Terminating.");
        System.exit(0);
    }

    wordScan.close();
}