RadioButton

RadioButton in JavaFX is used when you want the user to select one option from a group. Multiple RadioButtons can be grouped using a ToggleGroup so that selecting one automatically deselects the others.

Example: RadioButtons with ToggleGroup

FXML (hello-view.fxml)

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.RadioButton?>
<?import javafx.scene.control.ToggleGroup?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.VBox?>

<VBox spacing="10" alignment="CENTER"
      xmlns="http://javafx.com/javafx/17"
      xmlns:fx="http://javafx.com/fxml/1"
      fx:controller="org.example.demo.HelloController">

    <RadioButton fx:id="option1" text="Option 1"/>
    <RadioButton fx:id="option2" text="Option 2"/>
    <RadioButton fx:id="option3" text="Option 3"/>
    
    <Button text="Check Selected" onAction="#checkSelected"/>
</VBox>

Controller (HelloController.java)

package org.example.demo;

import javafx.fxml.FXML;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.control.Alert;

public class HelloController {

    @FXML
    private RadioButton option1;
    @FXML
    private RadioButton option2;
    @FXML
    private RadioButton option3;

    @FXML
    public void initialize() {
        // Create a ToggleGroup and assign RadioButtons
        ToggleGroup group = new ToggleGroup();
        option1.setToggleGroup(group);
        option2.setToggleGroup(group);
        option3.setToggleGroup(group);
        
        // Optional: set default selected
        option1.setSelected(true);
    }

    @FXML
    private void checkSelected() {
        RadioButton selected = (RadioButton) option1.getToggleGroup().getSelectedToggle();
        Alert alert = new Alert(Alert.AlertType.INFORMATION);
        alert.setTitle("Selected Option");
        alert.setHeaderText(null);
        alert.setContentText("You selected: " + selected.getText());
        alert.show();
    }
}

Key Points:

1. ToggleGroup ensures only one RadioButton can be selected at a time.
2. Use getSelectedToggle() to find out which option the user selected.
3. setSelected(true) allows you to set a default choice.