JavaFX has a binding API, which provides ways of binding one property to the other. This means that whenever one property's value is changed, the value of the bound property is updated automatically. An example of simple binding:

SimpleIntegerProperty first =new SimpleIntegerProperty(5); //create a property with value=5
SimpleIntegerProperty second=new SimpleIntegerProperty();

public void test()
{
    System.out.println(second.get()); // '0'
    second.bind(first);               //bind second property to first
    System.out.println(second.get()); // '5'
    first.set(16);                    //set first property's value
    System.out.println(second.get()); // '16' - the value was automatically updated
}

You can also bind a primitive property with applying an addition, subtraction, division, etc:

public void test2()
{
        second.bind(first.add(100));
        System.out.println(second.get()); //'105'
        second.bind(first.subtract(50));
        System.out.println(second.get()); //'-45'
}

Any Object can be put into SimpleObjectProperty:

SimpleObjectProperty<Color> color=new SimpleObjectProperty<>(Color.web("45f3d1"));

It is possible to create bidirectional bindings. In this case, properties depend on each other.

public void test3()
{
        second.bindBidirectional(first);
        System.out.println(second.get()+" "+first.get());
        second.set(1000);
        System.out.println(second.get()+" "+first.get()); //both are '1000'
}