JavaFX Alert

Controller.java

package sample;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.ButtonType;

import java.util.Optional;

public class Controller {

    @FXML
    void showDialog(ActionEvent event) {

        Alert alert = new Alert(Alert.AlertType.CONFIRMATION);
        alert.setTitle("Alert!");
        alert.setContentText("This is an alert");
        Optional<ButtonType> result = alert.showAndWait();


        if(result.isEmpty()){
            System.out.println("Alert closed");
        } else if(result.get() == ButtonType.OK){
            System.out.println("OK!");
        } else if(result.get() == ButtonType.CANCEL){
            System.out.println("Never!");
        }

    }
}