在JSF中实现购物篮时获取java.lang.ClassCastException

Question

我有一个篮子的问题。如何解决这类问题来解决呢?

java.lang.ClassCastException:pl.library.web.books.cdi。不能是CartBean$Proxy$_$$_WeldClientProxy转换为java.util.List

@Named
@SessionScoped
public class CartBean implements Serializable {
    private BookLDM book;
    private int quantity;
    public CartBean(BookLDM byId, int i) {
        this.book = byId;
        this.quantity = i;
    }
    public BookLDM getBook() {
        return book;
    }
    public void setBook(BookLDM book) {
        this.book = book;
    }
    public int getQuantity() {
        return quantity;
    }
    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }
    public CartBean() {}
}

@Named
@RequestScoped
public class BoxManager implements Serializable {
    private static final long serialVersionUID = 8267670504661589685L;
    @Inject
    private CartBean cart;
    @EJB
    private BookService bookService;
    public BoxManager() {}
    public CartBean getCart() {
        return cart;
    }
    public void addItem(final Long itemId) {
        if (cart == null) {
            List<CartBean> cart = new ArrayList<CartBean>();
            cart.add(new CartBean(this.bookService.getById(itemId), 1));
        } else {
            List<CartBean> cart = (List<CartBean>) getCart();
            int index = isExisting(itemId);
            if (index == -1) {
                cart.add(new CartBean(this.bookService.getById(itemId), 1));
            } else {
                int quantity = cart.get(index).getQuantity() + 1;
                cart.get(index).setQuantity(quantity);
            }
        }
    }
    private int isExisting(long id) {
        List<CartBean> cart = (List<CartBean>) getCart();
        for (int i = 0; i < cart.size(); i++) {
            if (cart.get(i).getBook().getId() == id) {
                return i;
            }
        }
        return -1;
    }
}

Answer 1

井信息明显。在这行List<CartBean> cart = (List<CartBean>) getCart();中，您试图将CartBean转换为List<CartBean>。这行不通。执行与上面几行相同的方式，首先创建新的ArrayList<CartBean>，然后创建由getCart()方法返回的新对象，最后将此对象添加到列表中。