Dynamically add CSS stylesheets in JavaFX

Question

I would like to add a CSS file which is located somewhere on the filesystem. The purpose is to write an application where the user can add JavaFX CSS files (which are create

Answer 1

Your problem is that you aren't using a URL. Here you can find more documentation on how the CSS is loaded alongside the CSS reference.

If you have the URL as a String you could set the CSS dynamically with an external file like so:

private boolean isANext = true;

public void start(Stage primaryStage) throws Exception {
    Button button = new Button("Change CSS");
    VBox vbox = new VBox(10);
    vbox.setAlignment(Pos.CENTER);
    vbox.getChildren().add(button);
    scene = new Scene(vbox, 200, 200);

    button.setOnAction(ev -> {
        // Alternate two stylesheets just for this demo.
        String css = isANext ? "file:///C:/temp/a.css" : "file:///C:/temp/b.css";
        isANext = !isANext;
        System.out.println("Loading CSS at URL " + css);

        scene.getStylesheets().clear();
        scene.getStylesheets().add(css);
    });

    primaryStage.setTitle("Title");
    primaryStage.setScene(scene);
    primaryStage.show();
}

In the a.css

.button {    
    -fx-text-fill: white;
    -fx-background-color: red;
}

And in b.css

.button {    
    -fx-text-fill: white;
    -fx-background-color: black;
}

Answer 2

scene.setUserAgentStylesheet("Assets/StyleSheets/Styless.css");

Answer 3

You can get the URL from java.io.File

File file = new File("style.css");
URL url = file.toURI().toURL();
scene.getStylesheets().add(url.toExternalForm());

or in short form

scene.getStylesheets().add((new File("style.css")).toURI().toURL().toExternalForm());

Answer 4

If css in same packaage simply use

scene.getStylesheets().add(getClass().getResource("style.css").toExternalForm());

Answer 5

The exception is thrown because the string "C:/test.css" is not a URI resource. Therefore you must convert your string into a URI resource.

As of Java 7 you can do:

String uri = Paths.get("C:/test.css").toUri().toString();
scene.getStylesheets().add(uri);