JavaFX 从 ToggleGroup 取消切换单选按钮

Question

我在 ToggleGroup 中有 2 个 RadioButton。我希望能够在单击时取消选择一个单选按钮（如果它已被选中）。

SampleController.java（控制器类）

public class SampleController {

    @FXML
    private RadioButton button1;

    @FXML
    private RadioButton button2;

    public void initializeButtons() {
        ToggleGroup toggles = new ToggleGroup();
        button1.setToggleGroup(toggles);
        button2.setToggleGroup(toggles);

        toggles.selectedToggleProperty().addListener(new ChangeListener<Toggle>(){

            public void changed(ObservableValue<? extends Toggle> ov, Toggle old_toggle, Toggle new_toggle) {

                
                System.out.println("curently : " + toggles.getSelectedToggle().isSelected());
             } 
        });
    }

}

如果我保留上面显示的代码，如果我切换一个按钮，那么另一个按钮会取消切换，反之亦然，但我无法取消切换两个按钮。我希望能够取消选择RadioButton，即移除其焦点并将其返回到其原始状态。

我正在寻找相当于

的东西

buttonGroup.clearSelection()

来自ButtonGroupin Swing班级。

---

在 StackOverflow 上看类似的问题，看来我必须这样做

(...)
public void changed(ObservableValue<? extends Toggle> ov, Toggle old_toggle, Toggle new_toggle) {

                if(toggles.getSelectedToggle() != null) {
                    if(toggles.getSelectedToggle().isSelected()){
                        toggles.getSelectedToggle().setSelected(false);
                    } else {
                        toggles.getSelectedToggle().setSelected(true);
                    }
                }
                System.out.println("curently : " + toggles.getSelectedToggle().isSelected());
             } 
(...)

但是每当我点击任何单选按钮时，添加这段代码的 sn-p 都会返回以下堆栈跟踪错误

Exception in thread "JavaFX Application Thread" java.lang.NullPointerException
        at SampleController$1.changed(SampleController.java:32)
        at SampleController$1.changed(SampleController.java:1)
        at javafx.base/com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:360)
        at javafx.base/com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
        at javafx.base/javafx.beans.property.ReadOnlyObjectPropertyBase.fireValueChangedEvent(ReadOnlyObjectPropertyBase.java:74)
        at javafx.base/javafx.beans.property.ReadOnlyObjectWrapper.fireValueChangedEvent(ReadOnlyObjectWrapper.java:102)
        at javafx.base/javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:113)
        at javafx.base/javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:147)
        at javafx.controls/javafx.scene.control.ToggleGroup$3.set(ToggleGroup.java:138)
        at javafx.controls/javafx.scene.control.ToggleGroup$3.set(ToggleGroup.java:120)
        at javafx.controls/javafx.scene.control.ToggleGroup.selectToggle(ToggleGroup.java:150)
        at javafx.controls/javafx.scene.control.ToggleButton$1.invalidated(ToggleButton.java:169)
        at javafx.base/javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:110)
        at javafx.base/javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:145)
        at javafx.controls/javafx.scene.control.ToggleButton.setSelected(ToggleButton.java:150)
        at javafx.controls/javafx.scene.control.ToggleButton.fire(ToggleButton.java:256)
        at javafx.controls/javafx.scene.control.RadioButton.fire(RadioButton.java:113)
        at javafx.controls/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:206)
        at javafx.controls/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
        at javafx.base/com.sun.javafx.event.CompositeEventHandler$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.access$1200(Scene.java:3579)
        at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
        at javafx.graphics/javafx.scene.Scene$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$2(GlassViewEventHandler.java:434)
        at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
        at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
        at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
        at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
        at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
        at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$11(GtkApplication.java:277)
        at java.base/java.lang.Thread.run(Thread.java:829)

Answer 1

在切换组中清除选择的内置方法是

toggles.selectToggle(null);

弄清楚何时调用它来实现你想要的有点棘手。实际上，您可能应该使用ToggleButtons 并重新设置它们的样式以使其看起来像RadioButtons，或者使用带有自定义外观的RadioButtons，将行为重新定义为您想要的。这两个都是相当多的工作（尤其是后者）。

以下快速破解似乎有效：

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.ButtonBase;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class App extends Application {

    private final ToggleGroup toggles = new ToggleGroup();

    @Override
    public void start(Stage stage) {

        VBox root = new VBox(5);
        root.setPadding(new Insets(20));

        root.getChildren().add(createToggle("Option 1"));
        root.getChildren().add(createToggle("Option 2"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.show();
    }

    private ButtonBase createToggle(String name) {
        RadioButton toggle = new RadioButton(name);
        toggle.addEventFilter(MouseEvent.MOUSE_PRESSED, e -> {
            if (toggle.isSelected()) {
                toggles.selectToggle(null);
                e.consume();
            }
        });
        toggle.setToggleGroup(toggles);
        return toggle;
    }

    public static void main(String[] args) {
        launch();
    }

}