无法编译Oracle文档示例

Question

这是我在这里的第一个问题，请多多包涵。

我正在尝试使用Oracle Java文档，但是当我尝试编译https://stackoverflow.com/a/8566871/5133329时，它不起作用。我已经尝试了所有我能想到的。这是一个古老的例子，所以可能是问题所在，但令人沮丧的是我无法弄清楚应该是一个小问题。

示例6使用InvalidationListener

package bindingdemo;

import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.binding.NumberBinding;
import javafx.beans.binding.Bindings;
import javafx.beans.InvalidationListener;
import javafx.beans.Observable;

class Bill {

    // Define the property
    private DoubleProperty amountDue = new SimpleDoubleProperty();

    // Define a getter for the property's value
    public final double getAmountDue(){return amountDue.get();}

    // Define a setter for the property's value
    public final void setAmountDue(double value){amountDue.set(value);}

     // Define a getter for the property itself
    public DoubleProperty amountDueProperty() {return amountDue;}

}

public class Main {

    public static void main(String[] args) {

        Bill bill1 = new Bill();
        Bill bill2 = new Bill();
        Bill bill3 = new Bill();

        NumberBinding total = Bindings.add(bill1.amountDueProperty().add(bill2.amountDueProperty()),
          bill3.amountDueProperty());
        total.addListener(new InvalidationListener() {

        @Override public void invalidated(Observable o) {
                System.out.println("The binding is now invalid.");
            }
        });

        // First call makes the binding invalid
        bill1.setAmountDue(200.00);

        // The binding is now invalid
        bill2.setAmountDue(100.00);
        bill3.setAmountDue(75.00);

        // Make the binding valid...
        System.out.println(total.getValue());

        // Make invalid... 
        bill3.setAmountDue(150.00);

        // Make valid...
        System.out.println(total.getValue());
    }
}

谢谢