Issue
I have 2 RadioButtons inside a ToggleGroup. I want to be able to deselect a radio button if it is already selected, upon clicking.
SampleController.java (Controller class)
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());
}
});
}
}
If I leave the code as presented above, if I toggle a button then the other one untoggles and vice-versa, but I can't untoggle both buttons. I want to be able to deselect a RadioButton, that is, to remove its focus and return it to its original state.
I am looking for something that is equivalent to
buttonGroup.clearSelection()
from the class ButtonGroup in Swing.
Looking at similar questions on StackOverflow it seems that I must do
(...)
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());
}
(...)
but adding this snippet of code returns the following stacktrace error whenever I click on any of the Radio buttons
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)
Solution
The built-in way to clear the selection in a toggle group is
toggles.selectToggle(null);
It's a little tricky to figure out when to call this to achieve what you want. Really you should probably either use ToggleButtons and re-style them so as to look like RadioButtons, or use RadioButtons with a custom skin that redefines the behavior to be what you want. Both of those are quite a lot of work (especially the latter).
The following quick hack seems to work though:
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();
}
}
Answered By - James_D
Answer Checked By - Marilyn (JavaFixing Volunteer)