Properties and Bindings - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 167

Sometimes it is necessary to convert a type-specific expression into an object expression holding the same type
of value. This can be done with the asObject() method in the type-specific expression class. The conversion back can
be done using static methods in the expressions class. For IntegerExpression these static methods are
static IntegerExpression integerExpression(ObservableIntegerValue value)
static <T extends java.lang.Number> IntegerExpression integerExpression(ObservableValue<T> value)
The program in Listing 4-6 is a modification of the triangle area example in Listing 4-5 that uses the fluent
interface API instead of calling factory methods in the Bindings class.
Listing 4-6. TriangleAreaFluentExample.java
import javafx.beans.binding.Bindings;
import javafx.beans.binding.NumberBinding;
import javafx.beans.binding.StringExpression;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
public class TriangleAreaFluentExample {
public static void main(String[] args) {
IntegerProperty x1 = new SimpleIntegerProperty(0);
IntegerProperty y1 = new SimpleIntegerProperty(0);
IntegerProperty x2 = new SimpleIntegerProperty(0);
IntegerProperty y2 = new SimpleIntegerProperty(0);
IntegerProperty x3 = new SimpleIntegerProperty(0);
IntegerProperty y3 = new SimpleIntegerProperty(0);
final NumberBinding area = x1.multiply(y2)
.add(x2.multiply(y3))
.add(x3.multiply(y1))
.subtract(x1.multiply(y3))
.subtract(x2.multiply(y1))
.subtract(x3.multiply(y2))
.divide(2.0D);
StringExpression output = Bindings.format(
"For A(%d,%d), B(%d,%d), C(%d,%d), the area of triangle ABC is %3.1f",
x1, y1, x2, y2, x3, y3, area);
x1.set(0); y1.set(0);
x2.set(6); y2.set(0);
x3.set(4); y3.set(3);
System.out.println(output.get());
x1.set(1); y1.set(0);
x2.set(2); y2.set(2);
x3.set(0); y3.set(1);
System.out.println(output.get());
}
}