Can we use create and use custom EventHandler classes in JAVAFX

javafxjavafx-2

I have a question on the Event Handling in JavaFX. As per the tutorial (and other examples that I came across), event handling is carried the following way in JavaFX:

Button addBtn = new Button("Add");
addBtn.setOnAction(new EventHandler<ActionEvent>() {
    @Override
    public void handle(ActionEvent event) {
            System.out.println("Add Clicked");
    }
});

But, I am wondering, if I can "handle" the button click the following way:

Button addBtn = new Button("Add");
addBtn.setOnAction(new addButtonClicked());

where addButtonClicked() is my own Class (with it's own set of methods and functionality) that I have defined and written to handle the actions for the button click.

Is there a way to attach my own event handler classes for buttons in JavaFX?

Best Answer

The EventHandler is an interface class. So, it should be "implements" not "extends"

private static class AddButtonClicked implements EventHandler<ActionEvent> {
     @Override
     public void handle(ActionEvent event) {
          System.out.println("My Very Own Private Button Handler");
     }
}

Related Solutions

Java – EventHandler in JavaFX a class or interface

The syntax

    new EventHandler<ActionEvent>() {
        @Override // <- notice the annotation, it overrides from the interface.
        public void handle(ActionEvent event) {
                System.out.print("Hello World !!");
        }
    }

creates an "anonymous inner class" that implements EventHandler, and defines the handle method. If you inspect the classes generated when you compile your project, you will probably find a class file named Sample$1 (or similar) which is the class generated for this code.

You can read up on inner (anonymous) classes here: http://docs.oracle.com/javase/tutorial/java/javaOO/innerclasses.html

To answer your question: EventHandler is an interface, and this code doesn't actually create an instance of it, but an instance of the newly declared anonymous class.

How to implement a really custom event handler that can handle any EventType in JavaFX

Try this

public class DataChangeHandler implements EventHandler<Event>{
    @Override
    public void handle(Event event) {
        System.out.println("My Very Own Private Handler For All Kind Of Events");
    }
}

Best Answer

Related Solutions

Java – EventHandler in JavaFX a class or interface

How to implement a really custom event handler that can handle any EventType in JavaFX

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