codeArea.setParagraphGraphicFactory(LineNumberFactory.get(codeArea, format, stylesheet));
codeArea.textProperty().addListener((obs, oldText, newText) -> {
codeArea.setStyleSpans(0, computeHighlighting(newText));
});
codeArea.replaceText(0, 0, sampleCode);
Scene scene = new Scene(new StackPane(codeArea), 600, 400);
scene.getStylesheets().add(stylesheet);
primaryStage.setScene(scene);
primaryStage.setTitle("Java Keywords Demo");