JavaFX RadioButton

Jakob Jenkov
Last update: 2016-05-15

A JavaFX RadioButton is a button that can be selected or not selected. The RadioButton is very similar to the JavaFX ToggleButton, but with the difference that a RadioButton cannot be "unselected" once selected. If RadioButtons are part of a ToggleGroup then once a RadioButton has been selected for the first time, there must be one RadioButton selected in the ToggleGroup .

The JavaFX RadioButton is represented by the class javafx.scene.control.RadioButton. The RadioButton class is a subclass of the ToggleButton class.

Creating a RadioButton

You create a JavaFX RadioButton using its constructor. Here is a JavaFX RadioButton instantiation example:

RadioButton radioButton1 = new RadioButton("Left");

The String passed as parameter to the RadioButton constructor is displayed next to the RadioButton.

Adding a RadioButton to the Scene Graph

To make a RadioButton visible you must add it to the scene graph of your JavaFX application. This means adding the RadioButton to a Scene, or as child of a layout which is attached to a Scene object.

Here is an example that attaches a JavaFX RadioButton to the scene graph:

package com.jenkov.javafx.controls;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.RadioButton;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;


public class RadioButtonExperiments extends Application  {


    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setTitle("HBox Experiment 1");

        RadioButton radioButton1 = new RadioButton("Left");

        HBox hbox = new HBox(radioButton1);

        Scene scene = new Scene(hbox, 200, 100);
        primaryStage.setScene(scene);
        primaryStage.show();

    }

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

}

The application resulting from running this example looks like this:

A JavaFX RadioButton displayed in the scene graph

Reading Selected State

The RadioButton class has a method named isSelected which lets you determine if the RadioButton is selected or not. The isSelected() method returns a boolean with the value true if the RadioButton is selected, and false if not. Here is an example:

boolean isSelected = radioButton1.isSelected();

ToggleGroup

You can group JavaFX RadioButton instances into a ToggleGroup. A ToggleGroup allows at most one RadioButton to be selected at any time.

Here is a JavaFX ToggleGroup example:

package com.jenkov.javafx.controls;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.RadioButton;
import javafx.scene.control.ToggleGroup;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;


public class RadioButtonExperiments extends Application  {


    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setTitle("HBox Experiment 1");

        RadioButton radioButton1 = new RadioButton("Left");
        RadioButton radioButton2 = new RadioButton("Right");
        RadioButton radioButton3 = new RadioButton("Up");
        RadioButton radioButton4 = new RadioButton("Down");

        ToggleGroup radioGroup = new ToggleGroup();

        radioButton1.setToggleGroup(radioGroup);
        radioButton2.setToggleGroup(radioGroup);
        radioButton3.setToggleGroup(radioGroup);
        radioButton4.setToggleGroup(radioGroup);

        HBox hbox = new HBox(radioButton1, radioButton2, radioButton3, radioButton4);

        Scene scene = new Scene(hbox, 200, 100);
        primaryStage.setScene(scene);
        primaryStage.show();

    }

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

}

The application resulting from running this example looks like this:

Four JavaFX RadioButton instances in a ToggleGroup displayed in the scene graph

Reading Selected State of a ToggleGroup

You can read which RadioButton of a ToggleGroup is selected using the getSelectedToggle() method, like this:

RadioButton selectedRadioButton =
        (RadioButton) toggleGroup.getSelectedToggle();

If no RadioButton is selected the getSelectedToggle() method returns null .

Jakob Jenkov

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