bool login = true;  // 로그인 변수

        public SelectMenu() // 생성자
        {
            display          = new Display();
            bookManagement   = new BookManagement(display);
            memberManagement = new MemberManagement(display);
            rental           = new Rental(display, memberManagement, bookManagement, this);
        }
 public Rental(Display display, MemberManagement memberManagement, BookManagement bookManagement, SelectMenu selectMenu) // 생성자
 {
     this.selecMenu        = selectMenu;
     this.display          = display;
     this.memberManagement = memberManagement;
     this.bookManagement   = bookManagement;
     memberData            = new MemberVO();
     bookData     = new BookVO();
     noList       = new ArrayList();
     nameList     = new ArrayList();
     quantityList = new ArrayList();
 }