Of course. Only related property has opposite semantic and is called disabled. Which means you can use setDisable (not setDisabled) and isDisabled. Since it is a JavaFX property you can also attach listeners to disabledProperty.
Check out the JavaFX documentation at http://docs.oracle.com/javafx/2/api/javafx/scene/Node.html#setDisable(boolean)
Code
button.setDisable(false)