ClassCastException class.Accomodation 无法转换为 class.Attraction

Question

这些是我的模特：

public class Accomodation {
    ...
}

和

public class Attraction extends Accomodation {
    ... 
    private String openingTime;
}

我的 Controller class:

中有这个方法

protected Accomodation getAccomodationByFormData(CrudView crudView) {
        Accomodation accomodation = new Accomodation();
        // setters
        return accomodation;
    }

在 AttractionController 中使用（扩展了之前的 Controller）：

@Override
    protected Accomodation getAccomodationByFormData(CrudView crudView) {
        Attraction attraction = (Attraction) super.getAccomodationByFormData(crudAttractionView);
        attraction.setOpeningTime(getOpeningTimeWithFormData()); 
        return attraction;
    }

另外一点 AttractionController 我有：

...
Attraction attraction = (Attraction) getAccomodationByFormData(crudAttractionView); // throws ClassCastException
...

但这给了我：

Exception in thread "JavaFX Application Thread" java.lang.ClassCastException: class models.Accomodation cannot be cast to class models.Attraction (models.Accomodation and models.Attraction are in unnamed module of loader 'app') at controllers.CrudAttractionController.getAccomodationByFormData(CrudAttractionController.java:302) at controllers.CrudAttractionController.lambda$buttonConfermaClicked(CrudAttractionController.java:143) at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86) at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49) at javafx.base/javafx.event.Event.fireEvent(Event.java:198) at javafx.graphics/javafx.scene.Node.fireEvent(Node.java:8879) at javafx.controls/javafx.scene.control.Button.fire(Button.java:200) at javafx.controls/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:206) at javafx.controls/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274) at javafx.base/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218) at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80) at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238) at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191) at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56) at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114) at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74) at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54) at javafx.base/javafx.event.Event.fireEvent(Event.java:198) at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3851) at javafx.graphics/javafx.scene.Scene$MouseHandler.access00(Scene.java:3579) at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849) at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588) at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397) at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295) at java.base/java.security.AccessController.doPrivileged(Native Method) at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent(GlassViewEventHandler.java:434) at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390) at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433) at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556) at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942) at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method) at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop(GtkApplication.java:277) at java.base/java.lang.Thread.run(Thread.java:834)

(Ps。注意 CrudAttractionView class 扩展了 CrudView)

我该如何解决？

编辑

景点

public class Attraction extends Accomodation {
    private String openingTime;

    public Attraction() {

    }

    public Attraction(Accomodation accomodation) {
        super(accomodation);
    }

    // getters and setters
}

住宿

public class Accomodation implements Serializable {
    protected String id;
    protected String name;
    protected Integer avarageRating;
    protected Integer avaragePrice;
    protected String phoneNumber;
    protected Address address;
    protected Point point;
    protected List<Review> reviews;
    protected Long totalReviews;
    protected Long totalRating;
    protected List<String> images;
    protected boolean hasCertificateOfExcellence;
    protected String addedDate;
    protected String lastModificationDate;

    public Accomodation() {

    }

    public Accomodation(Accomodation accomodation) {
    }

    // getters and setters
}

Answer 1

所有 Attraction 都是 Accomodation，但并非所有 Accomodation 都是 Attraction。

这意味着你不能安全地做:

Attraction attraction = (Attraction) super.getAccomodationByFormData(crudAttractionView);

即使您在 AttractionController 中（java 不会根据您的控制器名称更改 super.getAccomadation 的 return 类型）。

一个不需要任何框架的解决方案是做类似的事情：

Accomodation accomodation = super.getAccomodationByFormData(crudAttractionView);
Attraction attraction = new Attraction(accomodation);
attraction.setOpeningTime(getOpeningTimeWithFormData())

您只需要确保您有一个 Attraction 构造函数，它将接受 Accomodation 并将其字段复制到您的景点。

类似于：

public Attraction(Accomodation accomodation){
  attraction.setX(accomodation.getX())
  ...
}

或者只是调用 super(accomodation) 并在 Accomodation 中拥有一个构造函数，它将能够将一个住宿复制到一个新的住宿中（这样您就可以在以后的所有扩展中使用该构造函数类)

现在，您确保您的住宿实际上是一个景点，然后您将其投放。

在一个更简洁的示例中，它看起来像这样

import java.io.Serializable;

class Attraction extends Accomodation {

    public Attraction() {

    }

    public Attraction(Accomodation accomodation) {
        super(accomodation); // we let super do the simple mapping
    }

    // getters and setters

    public void setOpeningTime(String test){
        //

    }
    protected Accomodation getAccomodationByFormData() {
        Accomodation accomodation= new Accomodation();//super.getAccomodationByFormData(crudAttractionView);
        Attraction attraction = new Attraction(accomodation); // we convert our accomodation thanks to our constructor
        attraction.setOpeningTime("...");
        return attraction;
    }
}

class Accomodation implements Serializable {
    protected String id;
    protected String name;
    protected Integer avarageRating;
    protected Integer avaragePrice;
    protected String phoneNumber;
    protected Long totalReviews;
    protected Long totalRating;
    protected boolean hasCertificateOfExcellence;
    protected String addedDate;
    protected String lastModificationDate;

    public Accomodation(Accomodation accomodation) {
        this.id = accomodation.id;
        this.name = accomodation.name;
        this.avarageRating = accomodation.avarageRating;
        this.avaragePrice = accomodation.avaragePrice;
        this.phoneNumber = accomodation.phoneNumber;
        this.totalReviews = accomodation.totalReviews;
        this.totalRating = accomodation.totalRating;
        this.hasCertificateOfExcellence = accomodation.hasCertificateOfExcellence;
        this.addedDate = accomodation.addedDate;
        this.lastModificationDate = accomodation.lastModificationDate;
    }

    public Accomodation() {

    }

    // getters and setters
}

ClassCastException class.Accomodation 无法转换为 class.Attraction

ClassCastException class.Accomodation cannot be cast to class.Attraction

java

polymorphism

classcastexception