我正在尝试使用带有单元工厂的 javafx 组合框来呈现列表，我在 CellList 的覆盖 updateItem() 上使用了 setText，但是当我更改基础模型上的值时，我发现它没有ẗ影响组合框上的已部署列表。所以我尝试让它绑定两个属性并且它有效但是当尝试清除选择时我有一个异常。这是代码：
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.stage.Stage;
import javafx.util.Callback;
public class BasicComboBoxSample extends Application {
public static void main(String[] args) { launch(args); }
@Override public void start(Stage stage) {
final Employee john = new Employee("John");
final Employee jill = new Employee("Jill");
final Employee jack = new Employee("Jack");
final ComboBox<Employee> cboEmployees = new ComboBox();
cboEmployees.getItems().addAll(john, jill, jack);
cboEmployees.setValue(jill);
Button b = new Button("ChangeName");
b.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent actionEvent) {
john.setName("Maria");
}
});
Button c = new Button("Clear");
c.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent actionEvent) {
cboEmployees.getSelectionModel().clearSelection();
}
});
Button d = new Button("Select First");
d.setOnAction(new EventHandler<ActionEvent>() {
@Override
public void handle(ActionEvent actionEvent) {
cboEmployees.getSelectionModel().select(john);
}
});
Callback<ListView<Employee>, ListCell<Employee>> cellFactory = new Callback<ListView<Employee>, ListCell<Employee>>() {
@Override
public ListCell<Employee> call(ListView<Employee> listView) {
return new EmployeeListCell(); //To change body of implemented methods use File | Settings | File Templates.
}
};
cboEmployees.setButtonCell(new EmployeeListCell());
cboEmployees.setCellFactory(cellFactory);
final StackPane layout = new StackPane();
VBox v = new VBox();
v.getChildren().add(cboEmployees);
v.getChildren().add(b);
v.getChildren().add(c);
v.getChildren().add(d);
layout.getChildren().add(v);
layout.setStyle("-fx-background-color: cornsilk; -fx-padding: 15;");
stage.setScene(new Scene(layout));
stage.show();
}
class Employee {
public Employee(String name) { this.setName(name); }
private SimpleStringProperty name = new SimpleStringProperty("");
String getName() {
return name.get();
}
SimpleStringProperty nameProperty() {
return name;
}
void setName(String name) {
this.name.set(name);
}
}
public class EmployeeListCell extends ListCell<Employee> {
@Override
protected void updateItem(Employee emp, boolean b) {
super.updateItem(emp, b);
if(emp != null){
textProperty().bind(emp.nameProperty());
}
}
}
}
例外是：
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: A bound value cannot be set.
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:157)
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:67)
at javafx.beans.property.StringProperty.setValue(StringProperty.java:84)
at javafx.scene.control.Labeled.setText(Labeled.java:135)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.updateDisplayText(ComboBoxListViewSkin.java:420)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.updateDisplayNode(ComboBoxListViewSkin.java:399)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.getDisplayNode(ComboBoxListViewSkin.java:229)
at com.sun.javafx.scene.control.skin.ComboBoxBaseSkin.updateDisplayArea(ComboBoxBaseSkin.java:125)
at com.sun.javafx.scene.control.skin.ComboBoxBaseSkin.handleControlPropertyChanged(ComboBoxBaseSkin.java:120)
at com.sun.javafx.scene.control.skin.ComboBoxListViewSkin.handleControlPropertyChanged(ComboBoxListViewSkin.java:198)
at com.sun.javafx.scene.control.skin.SkinBase$3.changed(SkinBase.java:282)
at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:107)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:367)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:123)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:130)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:163)
at javafx.scene.control.ComboBoxBase.setValue(ComboBoxBase.java:148)
at javafx.scene.control.ComboBox.updateValue(ComboBox.java:416)
at javafx.scene.control.ComboBox.access$300(ComboBox.java:166)
at javafx.scene.control.ComboBox$6.changed(ComboBox.java:401)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:367)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ReadOnlyObjectWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyObjectWrapper.java:195)
at javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:161)
at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:130)
at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:163)
at javafx.scene.control.SelectionModel.setSelectedItem(SelectionModel.java:101)
at javafx.scene.control.ComboBox$ComboBoxSelectionModel$1.invalidated(ComboBox.java:448)
at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:155)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:100)
at javafx.beans.property.ReadOnlyIntegerWrapper$ReadOnlyPropertyImpl.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:195)
at javafx.beans.property.ReadOnlyIntegerWrapper.fireValueChangedEvent(ReadOnlyIntegerWrapper.java:161)
at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:130)
at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:163)
at javafx.scene.control.SelectionModel.setSelectedIndex(SelectionModel.java:67)
at javafx.scene.control.SingleSelectionModel.updateSelectedIndex(SingleSelectionModel.java:208)
at javafx.scene.control.SingleSelectionModel.clearSelection(SingleSelectionModel.java:67)
at de.thomasbolz.javafx.BasicComboBoxSample$2.handle(BasicComboBoxSample.java:45)
at de.thomasbolz.javafx.BasicComboBoxSample$2.handle(BasicComboBoxSample.java:42)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Node.fireEvent(Node.java:6863)
at javafx.scene.control.Button.fire(Button.java:179)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3328)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3168)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3123)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1563)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2265)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
at com.sun.glass.ui.View.handleMouseEvent(View.java:528)
at com.sun.glass.ui.View.notifyMouse(View.java:922)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication$3$1.run(GtkApplication.java:82)
at java.lang.Thread.run(Thread.java:722)