Question

我试图使用抽象类，并对其进行所有扩展，以将子类传递给方法并返回相同的类。最好仅通过代码来解释。

public abstract class AbstractRequestReBuilder {

    @Autowired
    private CreditCardUpdateProcessor creditCardUpdateProcessor;

    abstract BookingRequest rebuildRequest(BookingRequest request);

    public BillingDetails updateCard(BillingDetails billingDetails) {
        return creditCardUpdateProcessor.updateCreditCardInBillingDetails(billingDetails);
    }

}

@Component
public class HotelRequestReBuilder extends AbstractRequestReBuilder {

    public HotelBookingRequest rebuildRequest(HotelBookingRequest request) {
        BillingDetails billingDetails = request.getBillingDetails();
        BillingDetails modifiedBillingDetails = updateCard(billingDetails);
        request.setBillingDetails(modifiedBillingDetails);
        return request;
    }
}

其中

public class HotelBookingRequest extends BookingRequest<RoomDetail> implements Serializable {
}

当前，我收到一个编译器错误，指出rebuildRequest中未实现HotelRequestReBuilder。任何人都可以请让我知道如何解决它。

Answer 1

HotelRequestReBuilder.rebuildRequest(HotelBookingRequest)不会覆盖AbstractRequestReBuilder.rebuildRequest(BookingRequest)，它会使其过载。

最简单的解决方案是将HotelBookingRequest设置为AbstractRequestReBuilder的类型参数：

public abstract class AbstractRequestReBuilder<B extends BookingRequest<...>> {
    abstract B rebuildRequest(B request);
}

并使用以下代码实现它：

public class HotelRequestReBuilder extends AbstractRequestReBuilder<HotelBookingRequest> {

    public HotelBookingRequest rebuildRequest(HotelBookingRequest request) {
        BillingDetails billingDetails = request.getBillingDetails();
        BillingDetails modifiedBillingDetails = updateCard(billingDetails);
        request.setBillingDetails(modifiedBillingDetails);
        return request;
    }
}

这将解决您的编译时问题。只需注意，您需要为BookingRequest<...>使用适合AbstractRequestReBuilder的抽象级别的适当的type参数

在抽象方法中将子类用作参数和返回类型

1 个答案: