We can add menu separator to menu in JavaFX window on the fly as follows:
fileMenu.getItems().addAll(open, close, save, new SeparatorMenuItem(), exit);
The code above add a SeparatorMenuItem to file menu.
import javafx.application.Application; import javafx.application.Platform; import javafx.scene.Scene; import javafx.scene.control.Label; import javafx.scene.control.Menu; import javafx.scene.control.MenuBar; import javafx.scene.control.MenuItem; import javafx.scene.control.SeparatorMenuItem; import javafx.scene.layout.BorderPane; import javafx.stage.Stage; public class Main extends Application { //Create a label that will report the selection. private Label response = new Label("Menu Demo"); public static void main(String[] args) { launch(args);/*from w w w . j av a2 s .c om*/ } public void start(Stage myStage) { myStage.setTitle("Menus from java2s.com"); // Use a BorderPane for the root node. BorderPane rootNode = new BorderPane(); Scene myScene = new Scene(rootNode, 300, 300); myStage.setScene(myScene); // Create the menu bar. MenuBar mb = new MenuBar(); // Create the File menu. Menu fileMenu = new Menu("File"); MenuItem open = new MenuItem("Open"); MenuItem close = new MenuItem("Close"); MenuItem save = new MenuItem("Save"); MenuItem exit = new MenuItem("Exit"); fileMenu.getItems().addAll(open, close, save, new SeparatorMenuItem(), exit); // Add File menu to the menu bar. mb.getMenus().add(fileMenu); // the response label to the center position. rootNode.setTop(mb); rootNode.setCenter(response); myStage.show(); } }