JAVAFX UI CONTROLS AND MULTIMEDIA - Introduction to Java Programming: Comprehensive Version - page 637

16.5 RadioButton
Radio buttons, also known as option buttons , enable the user to choose a single item from a
group of choices. In appearance radio buttons resemble check boxes, but check boxes display
a square that is either checked or blank, whereas radio buttons display a circle that is either
filled (if selected) or blank (if not selected).
RadioButton is a subclass of ToggleButton . The difference between a radio button
and a toggle button is that a radio button displays a circle, but a toggle button is rendered
similar to a button. The UML diagrams for ToggleButton and RadioButton are shown in
Figure 16.9.

option buttons

The getter and setter methods for property
values and a getter for property itself are provided
in the class, but omitted in the UML diagram for brevity.

javafx.scene.control.ToggleButton

-selected: BooleanProperty
-toggleGroup:
ObjectProperty<ToggleGroup>

Indicates whether the button is selected.
Specifies the button group to which the button belongs.

+ToggleButton()
+ToggleButton(text: String)
+ToggleButton(text: String, graphic: Node)

Creates an empty toggle button.
Creates a toggle button with the specified text.
Creates a toggle button with the specified text and graphic.

javafx.scene.control.RadioButton

+RadioButton()
+RadioButton(text: String)

Creates an empty radio button.
Creates a radio button with the specified text.

F IGURE 16.9

ToggleButton and RadioButton are specialized buttons for making selections.

Here is an example of a radio button with text US , a graphic image, green text color, and
black border, and initially selected.

RadioButton rbUS = new RadioButton( "US" );
rbUS.setGraphic( new ImageView( "image/usIcon.gif" ));
rbUS.setTextFill(Color.GREEN);
rbUS.setContentDisplay(ContentDisplay.LEFT);
rbUS.setStyle( "-fx-border-color: black" );
rbUS.setSelected( true );
rbUS.setPadding( new Insets( 5 , 5 , 5 ,));

To group radio buttons, you need to create an instance of ToggleGroup and set a radio
button's toggleGroup property to join the group, as follows:

ToggleGroup group = new ToggleGroup();
rbRed.setToggleGroup(group);
rbGreen.setToggleGroup(group);
rbBlue.setToggleGroup(group);

This code creates a button group for radio buttons rbRed , rbGreen , and rbBlue so that
buttons rbRed , rbGreen , and rbBlue are selected mutually exclusively. Without grouping,
these buttons would be independent.
When a radio button is changed (selected or deselected), it fires an ActionEvent . To see
if a radio button is selected, use the isSelected() method.