JavaFX IntegerProperty create from SimpleIntegerProperty

import javafx.beans.binding.NumberBinding;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;

public class Main {
    public static void main(String[] args) {
        // Create two properties x and y
        IntegerProperty x = new SimpleIntegerProperty(100);
        IntegerProperty y = new SimpleIntegerProperty(200);

        // Create a binding: sum = x + y
        NumberBinding sum = x.add(y);//from w  w w.j  ava  2 s.co  m

        System.out.println("After creating sum:");
        System.out.println("sum.isValid(): " + sum.isValid());

        // Let us get the value of sum, so it computes its value and
        // becomes valid
        int value = sum.intValue();

        System.out.println("\nAfter requesting value:");
        System.out.println("sum.isValid(): " + sum.isValid());
        System.out.println("sum = " + value);

        // Change the value of x
        x.set(250);

        System.out.println("\nAfter changing x:");
        System.out.println("sum.isValid(): " + sum.isValid());

        // Get the value of sum again
        value = sum.intValue();

        System.out.println("\nAfter requesting value:");
        System.out.println("sum.isValid(): " + sum.isValid());
        System.out.println("sum = " + value);
    }
}