Javafx Fxml Controls CSS

JavaFX FXML, Controls, and CSS

Use this skill when the project should separate view markup, controller logic, and styling.

Example

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.VBox?>

<VBox xmlns="http://javafx.com/javafx/21"
      xmlns:fx="http://javafx.com/fxml/1"
      fx:controller="com.example.app.ui.HomeController"
      spacing="12">
    <padding>
        <Insets top="24" right="24" bottom="24" left="24" />
    </padding>

    <Label fx:id="titleLabel" text="Welcome" styleClass="title" />
    <Button text="Refresh" />
</VBox>

package com.example.app.ui;

import javafx.fxml.FXML;
import javafx.scene.control.Label;

public class HomeController {

    @FXML
    private Label titleLabel;

    @FXML
    private void refresh() {
        titleLabel.setText("Refreshed");
    }
}

.title {
    -fx-font-size: 20px;
    -fx-font-weight: bold;
}

Setup notes

• Keep controller classes focused on UI orchestration and delegate business logic elsewhere.
• Use stylesheet classes instead of inline style strings for maintainability.
• Resolve FXML resources via the classpath relative to the owning class or module.
• Use javafx-theming-icons-styling for broader theme-system, icon-pack, and CSS architecture work.

Gotchas

• fx:id mismatches fail at load time, not compile time.
• Modular applications must opens FXML controller packages to javafx.fxml.
• CSS selectors target JavaFX style classes and pseudo-classes, not web CSS semantics one-to-one.