Javafx adding ActionListener to button

If you want to e.g. reuse an EventHandler, define it like described in JavaFX Documentation as:

EventHandler<ActionEvent> buttonHandler = new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent event) {
        label.setText("Accepted");
        event.consume();
    }
};

You can now add your defined buttonHandler to the onAction of your button via:

button.setOnAction(buttonHandler);

And citing from the documentation providing the remove option for completeness:

To remove an event handler that was registered by a convenience method, pass null to the convenience method, for example, node1.setOnMouseDragged(null).

Resulting for you in:

button.setOnAction(null)

The documentation furthermore provides some examples how to add handler for specific events - it's a good read.

Just the same approach, but easier with lamda expressions:

button.setOnAction(event -> buttonSaveClicked());

I think this is how I should do. Creating the handler:

public EventHandler<Event> createSolButtonHandler()
{
    btnSolHandler = new EventHandler<Event>() {

        @Override
        public void handle(Event event) {
            System.out.println("Pressed!");
            biddingHelperFrame.getBtnSag().setVisible(false);
        }
    };
    return btnSolHandler;
}

Adding Handler to button:

btnSol.addEventHandler(MouseEvent.MOUSE_CLICKED, biddingHelperFrameController.createSolButtonHandler());