JavaFX Event Filters

Adding JavaFX Event Filters

The process of adding a JavaFX event filter to any node requires two things:

Event Type

The Event Type is defined as an object. In this scenario, an EventType object.

In JavaFX, there are numerous super types of events, depending on the input source and the sort of action the source was performing, like Input Event, Window Event, Action Event, and many more.

In JavaFX, 90 predefined EventTypes are divided based on the event source. For example, all user events such as mouse clicks and keystrokes are grouped into InputEvent, subdivided into MouseEvent, KeyEvent, and so on.

Code To Execute On The Event

Defining the code that an Event Filter will execute is really simple. An Event Filter, despite its name, is still an EventHandler object. EventHandler objects are a simple, functional interface with a single method.

An example code will be structured like this:

node.addEventFilter (<Type-of-Event>, new EventHandler<Type-of-Event>(){   
  public void handle(Type-of-Event){   
       //Your code goes here   
  });   

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Implementation

The following code illustrates working of Event Filter:

import javafx.application.Application;  
import javafx.event.EventHandler;  
import javafx.scene.Group;  
import javafx.scene.Scene;  
import javafx.scene.control.Label;  
import javafx.scene.control.TextField;  
import javafx.scene.input.KeyEvent;  
import javafx.stage.Stage;  
public class EventUI extends Application{  
  
    @Override  
    public void start(Stage primaryStage) throws Exception {  
      
        Label l1 = new Label(" Enter any text ");  
        Label l2 = new Label(" Event filtering ");  
          
        l1.setTranslateX( 100);  
        l1.setTranslateY( 100);  
          
        l2.setTranslateX( 100);  
        l2.setTranslateY( 150);  
          
        TextField tf1 = new TextField();  
        TextField tf2 = new TextField();  
          
        tf1.setTranslateX( 250);  
        tf1.setTranslateY( 100);  
        tf2.setTranslateX( 250);  
        tf2.setTranslateY( 150);  
        tf2.setMinWidth( 200);
          
        EventHandler<KeyEvent> newfilter = new EventHandler<KeyEvent>() {  
            @Override  
            public void handle(KeyEvent event) {  
                tf2.setText("Event filter used: "+event.getEventType());  
                tf1.setText(event.getText());  
                event.consume();  
            }  
        };  
          
        tf1.addEventFilter(KeyEvent.ANY,newfilter );  
          
        Group root = new Group();  
        root.getChildren().addAll(l1, l2, tf1, tf2);  
        Scene scene = new Scene(root, 500, 300);  
        primaryStage.setScene(scene);  
        primaryStage.setTitle(" JavaFX Event Filter ");  
        primaryStage.show();  
    }  
    public static void main(String[] args) {  
        launch(args);  
    }  
  
} 

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Execution

To execute the above program. You can follow the given steps:

1. Open the terminal in the same folder where you have saved your source code.
    
2. Enter the below code and hit enter.
   javac --module-path path/to/your/javaFx/modules --add-modules javafx.fxml,javafx.controls filename.java
    
3. After you hit enter a new file will automatically be generated namely filename.class
    
4. Now, enter the below command and hit enter to execute the above program.
   java --module-path path/to/your/javaFx/modules --add-modules javafx.fxml,javafx.controls filename.java
    
5. You have successfully executed the JavaFX program.

Output

Removing Event Filter

When a user no longer wants to handle events on a certain node, we can remove the event filter associated with that node by calling the removeEventFilter() method. This method accepts two arguments: the event type and the event filter's object.

node.removeEventFilter(Type-of-Event, eventfilter_Object);

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Frequently Asked Questions

What are the alternatives of JavaFX?

The most popular JavaFX alternatives and competitors include GWT, Vaadin, Qt, JSF, and Electron.

What is the recommended way of using JavaFX in your browser?

The Deployment Toolkit library is recommended for embedding a JavaFX application into a web page or launching it from within a web browser.

What are the use cases for the JavaFX library?

JavaFX is a Java library that can be used to create Rich Internet Applications. This library's applications can execute consistently across different platforms. JavaFX applications can run on a variety of platforms, including desktop computers, mobile phones, televisions, and tablets.

Conclusion

In this blog, we discussed the JavaFX Event Filters, their uses, adding Event Filters to a node, and implementations and removing them from a node.

Congratulations, you have reached the end. Hope you liked the blog, and it has added some knowledge to your life about JavaFX pause transition. Please look at these similar topics to learn more: JavaFX Introduction, JavaFX pause transition, JavaFX Box, JavaFX Sphere, JavaFX Lighting, JavaFX HBox, JavaFX VBox.

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