Javafx组合框自动完成返回错误

我想从数据库中筛选字符串数据，并从我的组合框中获取所选行的ID，但我得到以下错误

Exception in thread "JavaFX Application Thread" java.lang.ClassCastException: java.lang.String cannot be cast to com.kwesiaryee.combo.Country
at com.kwesiaryee.combo.ComboBoxSample$1.changed(ComboBoxSample.java:45)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyObjectPropertyBase.fireValueChangedEvent(ReadOnlyObjectPropertyBase.java:74)
at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:102)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.SelectionModel.setSelectedItem(SelectionModel.java:102)
at javafx.scene.control.ComboBox.lambda$new$152(ComboBox.java:249)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.control.ComboBoxBase.setValue(ComboBoxBase.java:150)
at com.sun.javafx.scene.control.skin.ComboBoxPopupControl.setTextFromTextFieldIntoComboBoxValue(ComboBoxPopupControl.java:405)
at com.sun.javafx.scene.control.skin.ComboBoxPopupControl.lambda$new$291(ComboBoxPopupControl.java:82)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:361)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.ReadOnlyBooleanPropertyBase.fireValueChangedEvent(ReadOnlyBooleanPropertyBase.java:72)
at javafx.scene.Node$FocusedProperty.notifyListeners(Node.java:7718)
at javafx.scene.Scene$13.invalidated(Scene.java:2077)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:111)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)
at javafx.scene.Scene$KeyHandler.setFocusOwner(Scene.java:3924)
at javafx.scene.Scene$KeyHandler.requestFocus(Scene.java:3971)
at javafx.scene.Scene$KeyHandler.access$1900(Scene.java:3910)
at javafx.scene.Scene.requestFocus(Scene.java:2044)
at javafx.scene.Node.requestFocus(Node.java:7879)
at com.sun.javafx.scene.control.behavior.TextFieldBehavior.mousePressed(TextFieldBehavior.java:248)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:198)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)

我试过几种方法来补救，但似乎都不管用。提供的数据来自mysql数据库。我得到的建议是找一个字符串生成器，但我还是被卡住了。当我像这样访问自动完成时会发生错误<代码>新的自动完成ComboxListener（combo）

然后尝试像这样获取id值

    combo.getSelectionModel().selectedItemProperty().addListener(new ChangeListener<Country>() {
        @Override
        public void changed(ObservableValue<? extends Country> observable, Country oldValue, Country newValue) {

            System.out.println(newValue.getName());
////                System.out.println(newValue.getContinent());
//                System.out.println("=================");

        }
    });

combo.getSelectionModel（）.SelectEditeProperty（）.addListener（新的ChangeListener（））{
@凌驾
public void changed（ObservalEvalue此异常清楚地表明您希望将字符串强制转换为对象。默认值属性为字符串，因此默认情况下您无法强制转换此属性。有两种方法可以处理此问题。
首先，您可以为这个特殊的盒子设置一个转换器，如以下示例所示：

combo.setConverter(new StringConverter <Country>() {

        @Override
        public String toString(Country object) {
            if(object == null) {
                return "";
            }
            return object.toString();
        }

        @Override
        public Country fromString(String string) {
            return combo
                    .getItems()
                    .stream()
                    .filter(country -> country.toString().equals(string))
                    .findFirst()
                    .orElseGet(()-> combo.getSelectionModel().getSelectedItem());
        }

    });

然后像这样获得您的价值：

AutoCompleteComboBox.autoCompleteComboBoxPlus(combo, (typedText, itemToCompare) -> itemToCompare.toString().toLowerCase().contains(typedText.toLowerCase()) || itemToCompare.toString().equals(typedText));

Country searchedCountry = AutoCompleteComboBox.getComboBoxValue(combo);

我希望这对您有很大帮助，但这只是我自己的项目。干杯：）
Soldin，非常感谢。转换器工作正常，非常完美，稍后将尝试自动完成。请提供一个演示问题的示例。
AutoCompleteComboBox.autoCompleteComboBoxPlus(combo, (typedText, itemToCompare) -> itemToCompare.toString().toLowerCase().contains(typedText.toLowerCase()) || itemToCompare.toString().equals(typedText));

Country searchedCountry = AutoCompleteComboBox.getComboBoxValue(combo);