Properties and Bindings - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 178

■ the full-lazy instantiation strategy incurs the cost of an extra field to stave off the need for property
instantiation a little longer. similarly, both the half-lazy and the full-lazy instantiation strategies incur costs of
implementation complexity and runtime performance to gain the benefit of a potentially reduced runtime memory
footprint. this is a classical trade-off situation in software engineering. Which strategy you choose will depend on
the circumstance of your application. our advice is to introduce optimization only if there is a need.

Caution

Using Selection Bindings
As you saw in the “Understanding the Bindings Utility Class” section earlier, the Bindings utility class contains seven
selection operators. The method signatures of these operators are:

•

select(Object root, String... steps)

•

selectBoolean(Object root, String... steps)

•

selectDouble(Object root, String... steps)

•

selectFloat(Object root, String... steps)

•

selectInteger(Object root, String... steps)

•

selectLong(Object root, String... steps)

selectString(Object root, String... steps)
These selection operators allow you to create bindings that observe deeply nested JavaFX Beans properties.
Suppose that you have a JavaFX bean that has a property, whose type is a JavaFX bean that has a property, whose type
is a JavaFX bean that has a property, and so on. Suppose also that you are observing the root of this properties chain
through an ObjectProperty . You can then create a binding that observes the deeply nested JavaFX Beans property
by calling one of the select methods whose type matches the type of the deeply nested JavaFX Beans property with
the ObjectProperty as the root, and the successive JavaFX Beans property names that reach into the deeply nested
JavaFX Beans property as the rest of the arguments.

•

■ there is another set of select methods that takes an ObservableValue as the first parameter. they were
introduced in JavaFX 2.0. the set of select methods that takes an Object as the first parameter allows us to use any
Java object, not merely JavaFX Beans, as the root of a selection binding.

Note

In the following example, we use a few classes from the javafx.scene.effect package— Lighting and Light —to
illustrate how the selection operator works. We teach you how to apply lighting to a JavaFX scene graph in a later
chapter of the topic. For now, our interest lies in the fact that Lighting is a JavaFX bean that has a property named
light whose type is Light , and that Light is also a JavaFX bean that has a property named color whose type is Color
(in javafx.scene.paint ).
The program in Listing 4-15 illustrates how to observe the color of the light of the lighting.

Listing 4-15. SelectBindingExample.java

import javafx.beans.binding.Bindings;
import javafx.beans.binding.ObjectBinding;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;