Java tutorial
import javafx.beans.binding.DoubleBinding; import javafx.beans.property.DoubleProperty; import javafx.beans.property.SimpleDoubleProperty; public class Main { public static void main(String[] args) { final DoubleProperty x = new SimpleDoubleProperty(null, "x", 2.0); final DoubleProperty y = new SimpleDoubleProperty(null, "y", 3.0); DoubleBinding area = new DoubleBinding() { private double value; { super.bind(x, y); } @Override protected double computeValue() { System.out.println("computeValue() is called."); return x.get() * y.get(); } }; System.out.println("area.get() = " + area.get()); x.set(5); y.set(7); System.out.println("area.get() = " + area.get()); } }