用户登录

String username = "fuckyou";
String password = "shityou";

for (int i = 0; i < 3; i++) {
    Scanner sc = new Scanner(System.in);

    System.out.println("请输入用户名：");
    String name = sc.nextLine();

    System.out.println("请输入密码：");
    String psw = sc.nextLine();

    if (username.equals(name) && password.equals(psw)) {
        System.out.println("登陆成功！");
        break;
    } else {
        if (i == 2) {
            System.out.println("您的账户已被锁定，请联系管理员！");
        } else {
            //i 0 1 2
            //  2 1 0
            System.out.println("登录失败，你还有" + (2 - i) + "次机会。");
        }
    }
}