JavaFX RadioButton
Jakob Jenkov |
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:
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:
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 .
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Jakob Jenkov | |
