CSS Styling in JavaFX

 CSS (Cascading Style Sheets) styling in JavaFX allows developers to customize the appearance of user interface components using familiar CSS syntax. JavaFX supports a subset of CSS properties and selectors, allowing you to style UI controls, layout panes, and other visual elements in your JavaFX applications. Here's an overview of CSS styling in JavaFX:

Key Concepts

1. Selectors: CSS selectors are used to target specific elements in the UI hierarchy for styling. JavaFX supports a variety of selectors, including type selectors, ID selectors, class selectors, and pseudo-class selectors.

2. Properties: CSS properties define the visual characteristics of UI components, such as colors, fonts, borders, margins, and padding. JavaFX supports a subset of CSS properties that are applicable to its UI controls and layout panes.

3. Stylesheets: CSS stylesheets contain sets of CSS rules that define the styling for various UI components in your JavaFX application. Stylesheets can be applied to individual nodes, scenes, or entire applications.

Styling UI Controls

JavaFX provides a rich set of UI controls that can be styled using CSS. You can apply CSS styles to individual controls by specifying style class names, inline styles, or using the `setStyle()` method in code. Here are some common UI controls and their CSS styling properties:

- Button: `button`, `default-button`, `hover`, `pressed`

- Label: `label`, `text-fill`, `font-size`, `font-family`

- TextField: `text-field`, `prompt-text`, `background`, `border`

- ComboBox: `combo-box`, `arrow-button`, `list-cell`, `combo-box-base`

Styling Layout Panes

JavaFX layout panes, such as `VBox`, `HBox`, `BorderPane`, and `GridPane`, can also be styled using CSS. You can apply CSS styles to layout panes to control their spacing, alignment, background color, and borders.

Using External Stylesheets

One of the advantages of CSS styling in JavaFX is the ability to define styles in external CSS files and apply them to your application. This allows for better separation of concerns and easier maintenance of styling code. To apply an external stylesheet to your JavaFX application, use the `getStylesheets().add()` method on the scene or stage.

Example

Here's an example of how to style a JavaFX application using CSS:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class StylingExample extends Application {

    @Override
    public void start(Stage primaryStage) {
        Button button = new Button("Click Me");
        StackPane root = new StackPane(button);

        Scene scene = new Scene(root, 300, 250);
        // Apply external stylesheet
        scene.getStylesheets().add(getClass().getResource("styles.css").toExternalForm());

        primaryStage.setScene(scene);
        primaryStage.setTitle("Styling Example");
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }
}

And the contents of `styles.css`:

/* styles.css */
.button {
    -fx-background-color: #4CAF50; /* Green */
    -fx-text-fill: white;
    -fx-font-size: 16px;
    -fx-padding: 10px 20px;
}

.button:hover {
    -fx-background-color: #45a049; /* Darker Green */
}

In this example, the button is styled using an external stylesheet (`styles.css`) that defines the background color, text color, font size, and padding for the button. The `:hover` pseudo-class is used to change the button's background color when hovered over.

Conclusion

CSS styling in JavaFX allows developers to customize the appearance of UI controls and layout panes using familiar CSS syntax. By applying CSS styles to your JavaFX applications, you can create visually appealing and consistent user interfaces with ease. Whether you're a beginner or an experienced developer, mastering CSS styling in JavaFX is essential for building modern and professional-looking applications.