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

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

    // Create a binding: sum = x + y
    NumberBinding sum = x.add(y);

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

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

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