Combobox JavaFX组合框的Bug？

我的一位开发人员尝试根据用户类型将ComboBox扩展为autofilter：

public class AutoCompleteComboBox<T> extends ComboBox<T> {

    private FilteredList<T> filteredItems;
    private SortedList<T> sortedItems;

    public AutoCompleteComboBox() {
        setEditable(true);
        setOnKeyReleased(e -> handleOnKeyReleasedEvent(e));
        setOnMouseClicked(e -> handleOnMouseClicked(e));
    }

    private void handleOnMouseClicked(MouseEvent e) {
        getItems().stream()
                .filter(item -> item.toString().equals(getEditor().getText()))
                .forEach(item -> getSelectionModel().select(item));
        setCaretPositionToEnd();
    }

    private void handleOnKeyReleasedEvent(KeyEvent e) {
        if (e.getCode() == KeyCode.UP || e.getCode() == KeyCode.DOWN) {
            getItems().stream()
                .filter(item -> item.toString().equals(getEditor().getText()))
                .forEach(item -> getSelectionModel().select(item));
            show();
            setCaretPositionToEnd();
        } else if (e.getCode() == KeyCode.ENTER || e.getCode() == KeyCode.TAB) {
                String editorStr = getEditor().getText();
                getSelectionModel().clearSelection();
                getEditor().setText(editorStr);
                setItems(this.sortedItems);
                getItems().stream()
                    .filter(item -> item.toString().equals(editorStr))
                    .forEach(item -> getSelectionModel().select(item));

                getEditor().selectEnd();
                if (e.getCode() == KeyCode.ENTER) {
                    getEditor().deselect();
                }
                hide();
        } else if (e.getText().length() == 1) {
            getSelectionModel().clearSelection();
            if (getEditor().getText().length() == 0) {
                getEditor().setText(e.getText());
            }
            filterSelectionList();
            show();
        } else if (e.getCode() == KeyCode.BACK_SPACE && getEditor().getText().length() > 0) {
            String editorStr = getEditor().getText();
            getSelectionModel().clearSelection();
            getEditor().setText(editorStr);
            int beforeFilter = getItems().size();
            filterSelectionList();
            int afterFilter = getItems().size();
            if (afterFilter > beforeFilter) {
                hide();
            }
            show();
        } else if (e.getCode() == KeyCode.BACK_SPACE && getEditor().getText().length() == 0) {
            clearSelection();
            hide();
            show();
        }
    }

    private void filterSelectionList() {
        setFilteredItems();
        setCaretPositionToEnd();
    }

    private void setFilteredItems() {
        filteredItems.setPredicate(item -> 
                item.toString().toLowerCase().startsWith(getEditor().getText().toLowerCase()));
    }

    private void setCaretPositionToEnd() {
        getEditor().selectEnd();
        getEditor().deselect();
    }

    public void setInitItems(ObservableList<T> values) {
        filteredItems = new FilteredList<>(values);
        sortedItems = new SortedList<>(filteredItems);
        setItems(this.sortedItems);
    }

    public void clearSelection() {
        getSelectionModel().clearSelection();
        getEditor().clear();
        if (this.filteredItems != null) {
            this.filteredItems.setPredicate(item -> true);
        }
    }

    public T getSelectedItem() {
        T selectedItem = null;
        if (getSelectionModel().getSelectedIndex() > -1) {
            selectedItem = getItems().get(getSelectionModel().getSelectedIndex());
        }
        return selectedItem;
    }

    public void select(String value) {
        if (!value.isEmpty()) {
            getItems().stream()
                .filter(item -> value.equals(item.toString()))
                .findFirst()
                .ifPresent(item -> getSelectionModel().select(item));
        }
    }
}

引发的异常：

Exception in thread "JavaFX Application Thread" java.lang.ClassCastException: java.lang.String cannot be cast to cache.CodeTableValue
       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$FocusedProperty.notifyListeners(Node.java:7718)
       at javafx.scene.Node.setFocused(Node.java:7771)
       at javafx.scene.Scene$KeyHandler.setWindowFocused(Scene.java:3932)
       at javafx.scene.Scene$KeyHandler.lambda$new$11(Scene.java:3954)
       at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)
       at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
       at javafx.beans.property.ReadOnlyBooleanPropertyBase.fireValueChangedEvent(ReadOnlyBooleanPropertyBase.java:72)
       at javafx.beans.property.ReadOnlyBooleanWrapper.fireValueChangedEvent(ReadOnlyBooleanWrapper.java:103)
       at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:110)
       at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:144)
       at javafx.stage.Window.setFocused(Window.java:439)
       at com.sun.javafx.stage.WindowPeerListener.changedFocused(WindowPeerListener.java:59)
       at com.sun.javafx.tk.quantum.GlassWindowEventHandler.run(GlassWindowEventHandler.java:100)
       at com.sun.javafx.tk.quantum.GlassWindowEventHandler.run(GlassWindowEventHandler.java:40)
       at java.security.AccessController.doPrivileged(Native Method)
       at com.sun.javafx.tk.quantum.GlassWindowEventHandler.lambda$handleWindowEvent$423(GlassWindowEventHandler.java:150)
       at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
       at com.sun.javafx.tk.quantum.GlassWindowEventHandler.handleWindowEvent(GlassWindowEventHandler.java:148)
       at com.sun.glass.ui.Window.handleWindowEvent(Window.java:1266)
       at com.sun.glass.ui.Window.notifyFocus(Window.java:1245)
       at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
       at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
       at java.lang.Thread.run(Thread.java:745)

如果editableFlag为false，则此操作有效。当我们允许用户在组合框中键入内容以过滤内容时，就会发生这种情况。没有绑定，我们就不会出现异常，并且值设置正确

我一直在深入挖掘这个异常，并在这里抛出它：

com.sun.javafx.binding.ExpressionHelper.Generic.fireValueChangedEvent()

                if (curChangeSize > 0) {
                    final T oldValue = currentValue;
                    currentValue = observable.getValue();
                    final boolean changed = (currentValue == null)? (oldValue != null) : !currentValue.equals(oldValue);
                    if (changed) {
                        for (int i = 0; i < curChangeSize; i++) {
                            try {
                                curChangeList[i].changed(observable, oldValue, currentValue);
                            } catch (Exception e) {
                                Thread.currentThread().getUncaughtExceptionHandler().uncaughtException(Thread.currentThread(), e);
                            }
                        }
                    }
                }

我曾尝试向编辑器添加一个StringConverter，以查看这是否可以纠正问题，但它仍然会引发此异常。也许我们试图处理这一切都是错误的

---

基本上，我们希望在用户输入字段时过滤组合框选择项。如果有不同的处理方法，请让我知道，但目前，我认为这可能是JDK中的一个bug？如果字段未绑定，则我们没有问题，但一旦绑定，当字段失去焦点或按下enter键时会发生此异常。

我已使用您的控件创建了一个快速示例：

@Override
public void start(Stage primaryStage) {

    AutoCompleteComboBox<CodeTableValue> myAutoCompleteBox = 
            new AutoCompleteComboBox<>();
    myAutoCompleteBox.setInitItems(FXCollections.observableArrayList(new CodeTableValue("One", "1"), 
            new CodeTableValue("Two", "2"), new CodeTableValue("Three", "4")));

    StackPane root = new StackPane(myAutoCompleteBox);
    myAutoCompleteBox.getSelectionModel().selectedItemProperty().addListener((obs, ov, nv) -> {
                    System.out.println(nv);
      });

    Scene scene = new Scene(root, 300, 250);
    primaryStage.setScene(scene);
    primaryStage.show();
}

public AutoCompleteComboBox(StringConverter<T> converter) {
    setEditable(true);
    setOnKeyReleased(e -> handleOnKeyReleasedEvent(e));
    setOnMouseClicked(e -> handleOnMouseClicked(e));

    super.setConverter(converter);
}

我可以在完成键入并单击enter以提交值并离开控件后复制您的异常：

java.lang.ClassCastException: java.lang.String cannot be cast to CodeTableValue

例外情况是，在编辑模式下从组合框使用的

文本字段

将始终返回

字符串

，但您强制自定义组合框使用

CodeTableValue

类

解决方案只是提供了一种使用

StringConverter

在字符串和

CodeTableValue

之间进行转换的方法

所以我修改了你的控件：

@Override
public void start(Stage primaryStage) {

    AutoCompleteComboBox<CodeTableValue> myAutoCompleteBox = 
            new AutoCompleteComboBox<>();
    myAutoCompleteBox.setInitItems(FXCollections.observableArrayList(new CodeTableValue("One", "1"), 
            new CodeTableValue("Two", "2"), new CodeTableValue("Three", "4")));

    StackPane root = new StackPane(myAutoCompleteBox);
    myAutoCompleteBox.getSelectionModel().selectedItemProperty().addListener((obs, ov, nv) -> {
                    System.out.println(nv);
      });

    Scene scene = new Scene(root, 300, 250);
    primaryStage.setScene(scene);
    primaryStage.show();
}

public AutoCompleteComboBox(StringConverter<T> converter) {
    setEditable(true);
    setOnKeyReleased(e -> handleOnKeyReleasedEvent(e));
    setOnMouseClicked(e -> handleOnMouseClicked(e));

    super.setConverter(converter);
}

公共自动完成组合框（StringConverter转换器）{
可编辑设置（真）；
setOnKeyReleased（e->HandleOnKeyReleaseEvent（e））；
setOnMouseClicked（e->HandleMouseClicked（e））；
super.setConverter（转换器）；
}

现在在示例中：

AutoCompleteComboBox<CodeTableValue> myAutoCompleteBox = 
            new AutoCompleteComboBox<>(new StringConverter<CodeTableValue>() {

        @Override
        public String toString(CodeTableValue object) {
            if (object != null) {
                return object.getValue();
            } 
            return null;
        }

        @Override
        public CodeTableValue fromString(String string) {
            return new CodeTableValue(string, string);
        }

    });

自动完成组合框myAutoCompleteBox=
新的自动完成组合框（新的StringConverter（）{
@凌驾
公共字符串toString（CodeTableValue对象）{
if（对象！=null）{
返回object.getValue（）；
} 
返回null；
}
@凌驾
public CodeTableValue fromString（字符串字符串）{
返回新的CodeTableValue（字符串，字符串）；
}
});

现在它可以工作了，没有了

ClassCastException

---

显然，您必须提供一种方法来键入字符串（对于

code

或

value

），然后从中检索另一个字符串。

谢谢！这很有效。我把转换器放在编辑器上，而不是控件上！

AutoCompleteComboBox<CodeTableValue> myAutoCompleteBox = 
            new AutoCompleteComboBox<>(new StringConverter<CodeTableValue>() {

        @Override
        public String toString(CodeTableValue object) {
            if (object != null) {
                return object.getValue();
            } 
            return null;
        }

        @Override
        public CodeTableValue fromString(String string) {
            return new CodeTableValue(string, string);
        }

    });