CSS, also referred to as Cascading Style Sheet, is a simple design language intended to simplify the process of making web pages presentable and user friendly. It allows us to define the appearance of user interface elements of a web page. Using CSS, we can control the color of the text, style of fonts, spacing between paragraphs, size of columns and layout. Apart from these, we can also control the background images or colors that are used, layout designs, variations in viewport for different devices and screen sizes as well as a variety of other effects.

Generally, CSS is widely used in web development, but it can also be applied to JavaFX application. In this tutorial, we are going to learn how to use the CSS in JavaFX application.

CSS in JavaFX

JavaFX provides us the facility of using CSS to enhance the look and feel of the application. The package javafx.css contains the classes that are used to apply CSS for JavaFX applications.

A CSS comprises of style rules that are interpreted by the browser and then applied to the corresponding elements in our document.

A style rule is made of three parts, which are as follows −

• Selector − A selector is an HTML tag at which a style will be applied. This could be any tag like <h1> or <table>, etc.

• Property − A property is a type of attribute of the HTML tag. In simpler terms, all the HTML attributes are converted into CSS properties. They could be color, border, etc.

• Value − Values are assigned to properties. For example, a color property can have value either red or #F1F1F1, etc.

we can put CSS Style Rule Syntax as follows −

selector { property: value }

The default style sheet used by JavaFX is modena.css. It is found in the JavaFX runtime jar.

Adding Style Sheet in JavaFX

we can add our own style sheet to a scene in JavaFX using the getStylesheets() method as shown below −

Scene scene = new Scene(new Group(), 500, 400); 
scene.getStylesheets().add("path/stylesheet.css");

Adding Inline Style Sheets in JavaFX

we can also add in-line styles using the setStyle() method. These styles consist of only key-value pairs and they are applicable to the nodes on which they are set. Following is a sample code of setting an inline style sheet to a button.

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

Example

Assume that we have developed an JavaFX application which displays a form with a Text Field, Password Field, Two Buttons. By default, this form looks as shown in the following screenshot −

The following JavaFX code demonstrates how to add styles to the above application using CSS. Save this code in a file with the name CssExample.java.

import javafx.application.Application; 
import static javafx.application.Application.launch; 
import javafx.geometry.Insets; 
import javafx.geometry.Pos; 
import javafx.scene.Scene; 
import javafx.scene.control.Button; 
import javafx.scene.control.PasswordField; 
import javafx.scene.layout.GridPane; 
import javafx.scene.text.Text; 
import javafx.scene.control.TextField; 
import javafx.stage.Stage;  

public class CssExample extends Application { 
   @Override 
   public void start(Stage stage) {      
      //creating label email 
      Text text1 = new Text("Email");       
      
      //creating label password 
      Text text2 = new Text("Password"); 
       
      //Creating Text Filed for email        
      TextField textField1 = new TextField();       
      
      //Creating Text Filed for password        
      PasswordField textField2 = new PasswordField();  
       
      //Creating Buttons 
      Button button1 = new Button("Submit"); 
      Button button2 = new Button("Clear");  
      
      //Creating a Grid Pane 
      GridPane gridPane = new GridPane();    
      
      //Setting size for the pane 
      gridPane.setMinSize(400, 200);
      
      //Setting the padding  
      gridPane.setPadding(new Insets(10, 10, 10, 10)); 
      
      //Setting the vertical and horizontal gaps between the columns 
      gridPane.setVgap(5); 
      gridPane.setHgap(5);       
      
      //Setting the Grid alignment 
      gridPane.setAlignment(Pos.CENTER); 
       
      //Arranging all the nodes in the grid 
      gridPane.add(text1, 0, 0); 
      gridPane.add(textField1, 1, 0); 
      gridPane.add(text2, 0, 1);       
      gridPane.add(textField2, 1, 1); 
      gridPane.add(button1, 0, 2); 
      gridPane.add(button2, 1, 2); 
       
      //Styling nodes  
      button1.setStyle("-fx-background-color: darkslateblue; -fx-text-fill: white;"); 
      button2.setStyle("-fx-background-color: darkslateblue; -fx-text-fill: white;"); 
       
      text1.setStyle("-fx-font: normal bold 20px ''serif'' "); 
      text2.setStyle("-fx-font: normal bold 20px ''serif'' ");  
      gridPane.setStyle("-fx-background-color: BEIGE;"); 
       
      // Creating a scene object 
      Scene scene = new Scene(gridPane, 400, 300); 
       
      // Setting title to the Stage   
      stage.setTitle("CSS Example in JavaFX"); 
         
      // Adding scene to the stage 
      stage.setScene(scene);
      
      //Displaying the contents of the stage 
      stage.show(); 
   } 
   public static void main(String args[]){ 
      launch(args); 
   } 
}

Compile and execute the saved java file from the command prompt using the following commands.

javac --module-path %PATH_TO_FX% --add-modules javafx.controls CssExample.java 
java --module-path %PATH_TO_FX% --add-modules javafx.controls CssExample

Output

On executing, the above program generates a JavaFX window as shown below.