Creating a simple slider in javaFX - javafx

Question

What i am trying to achieve is to create a method next to the initialize method, that can handle the current value of a slidebar. I want that method to pass back the value into a Timeline. The problem i am facing is that the method that handles the slider and when its changing is a void method, but i need that value in double type.
I am having hard time understanding the concept of addlistener and what the difference is between Observable, ObservableValue, InvalidationListener, and ChangeListener.
/*DATA FIELD*/
private double cycle;
private Timeline loop;
#FXML
private Slider slider1;
/*METHODS*/
#FXML
public double frequency(){
slider1.valueProperty().addListener(new InvalidationListener(){
#Override
public void invalidated(Observable observable){
cycle = slider1.setValue(slider1.getValue());
}});
return cycle;
public void initialize(URL url, ResourceBundle rb) {
slider1 = new Slider(100, 3000, 500);
loop = new Timeline(new KeyFrame(Duration.millis(cycle), (ActionEvent event) -> {
gb.nextGen(gb.getBoard());
graphic.draw(gb.getBoard());
}

Answer 1

A good way to do this is using property bindings instead. You could bind the value of your slider, to update any other field. An example to bind your slider to a label:
#FXML
private Label label;
#FXML
private Slider slider;
#Override
public void initialize(URL url, ResourceBundle rb) {
label.textProperty().bindBidirectional(slider.valueProperty(), new NumberStringConverter());
}
And in your concrete case, you could bind it to a double property. You could do something as the following:
private final DoubleProperty doubleProperty = new SimpleDoubleProperty();
#FXML
private Slider slider;
#Override
public void initialize(URL url, ResourceBundle rb) {
doubleProperty.bind(slider.valueProperty());
//When you're in need to pass the primitive forward, get it from the property
doubleProperty.get();
}
The binding basically does the following: change the slider, change whatever it's bound to. When using bidirectional binding, it goes both ways. E.g. bind a slider to a textfield, both update each other.