Using the JavaFX UI Controls - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 247

alignToggleGroup.selectToggle(alignToggleGroup.getToggles().get(0));
alignToggleGroup.selectedToggleProperty().addListener((ov, oldValue, newValue) -> {
ToggleButton tb = ((ToggleButton) alignToggleGroup.getSelectedToggle());
if (tb != null) {
System.out.println(tb.getId() + " selected");
}
});

This use case is the classic Left-Alignment button in many document editing applications, where only one of the
Alignment buttons may be selected at any given time. The ToggleGroup instance is passed into the setToggleGroup()
method of the ToggleButton shown in the preceding snippet to provide this mutually exclusive behavior.
In addition to providing mutual exclusivity, the ToggleGroup instance is used in this snippet for two purposes:

1. To initially select the first ToggleButton in the group, by using the selectToggle()

method of the ToggleGroup instance.

2. To detect when the currently selected ToggleButton changes. This is accomplished by

adding a ChangeListener to the selectedToggle property of the ToggleGroup , and then
using its getSelectedToggle() method to ascertain which ToggleButton is currently
selected. Note that this is generally preferred over putting an onAction event handler in
each of the toggle buttons that are participating in a toggle group.

Inserting a Separator into a Toolbar
It is sometimes useful to visually separate toolbar buttons by using the vertical separators shown in Figure 6-3 .
To accomplish this, use the Separator class as shown in this line from Listing 6-4:

new Separator(Orientation.VERTICAL),

Although we didn't make use of separators in the menus of this StarterApp program, Separator objects may be
used in menus as well. Of course, separators used in menus typically have a HORIZONTAL Orientation .

Creating a TabPane and Defining Tabs
One of the principles of UI design is called progressive disclosure, which states that a UI should reveal its functionality
progressively rather than inundating the user with all of its functionality at once. The TabPane is a good example of
this principle in use, as each tab discloses its functionality while hiding the functionality contained in the other tabs.
To create the TabPane instance, our StarterApp program defines a method that we've arbitrarily named
createTabs() , shown in Listing 6-5. This method leverages the TabPane and Tab classes, and returns a TabPane
instance that contains the desired Tab objects.

Listing 6-5. The createTabs() Method Located in StarterAppMain.java
TabPane createTabs() {
final WebView webView = new WebView();
Tab tableTab = new Tab("TableView");
tableTab.setContent(createTableDemoNode());
tableTab.setClosable(false);
Tab accordionTab = new Tab("Accordion/TitledPane");
accordionTab.setContent(createAccordionTitledDemoNode());
accordionTab.setClosable(false);