如何将CSS添加到JavaFx元素

Question

I'm trying to add a an external .css file to a Java FX scene graph as follows:

File f = new File("../theming/css/test.css");
scene.getStylesheets().clear();
scene.getStylesheets().add("file:///" + f.getAbsolutePath().replace("\\", "/"));

test.css

.custom-background {
    -fx-background-color: #1d1d1d;
    -fx-background-color: red;
    -fx-padding: 15;
    -fx-spacing: 10;
}

.label {
    -fx-font-size: 11pt;
    -fx-font-family: "Segoe UI Semibold";
    -fx-text-fill: white;
    -fx-opacity: 0.6;
}

The style classes get added well, except where I try to add a custom class to an element:

Hbox hbox = new HBox();
hbox.setSpacing(10);
hbox.setMinSize(400, 300);
hbox.getStyleClass().add("custom-background");

That doesn't get picked up.

What could I be doing wrong?

Thank you in advance.

Answer 1

Don't try to convert the file name to a URL yourself. Instead use the build in methods of the File class:

scene.getStylesheets().setAll(f.toURI().toURL().toExternalForm());

This assumes the file is located at the specified path relative to the current working directory when the application is run. In most cases using a relative file path is a bad idea, since running from a different directory will break the program. It would be preferable to include the css file as resource.