➊

    public CartItem() {
        // TODO Auto-generated constructor stub
    }

➋

    public CartItem(Book book) {
        super();
        this.book = book;
        this.quantity = 1;
        this.totalPrice = book.getUnitPrice();
    } 

➌

    public Book getBook() {
        return book;
    }

    public void setBook(Book book) {
        this.book = book;
        this.updateTotalPrice();
    }

    public int getQuantity() {
        return quantity;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
        this.updateTotalPrice();
    }

    public int getTotalPrice() {
        return totalPrice;
    }