Java FX Chapter 15 Flashcards

JavaFX Event System

• Root class for events is javafx.event.Event, a subclass of java.util.EventObject.
• Subclasses of Event address various event types: action, window, mouse, and key events.
• Nodes that can fire events mean their subclasses can also trigger the same event types.

Event Handling

• Handler class must implement the specific event-handler interface corresponding to the event type.
• JavaFX includes an EventHandler<T> interface containing the handle(T e) method for processing events.

Registration of Event Handlers

• Event handlers must be registered with the source object using specific methods:
  • setOnAction for action events.
  • setOnMousePressed for mouse-pressed events.
  • setOnKeyPressed for key-pressed events.

Class Structures

• Inner Class: Defined within another class, allowing direct access to outer class data and methods.
• Anonymous Inner Class: A nameless class defined at the point of instantiation, simplifying event handling code.
  • Can leverage lambda expressions for functional interface handlers.

Interfaces and Events

• Functional Interface: Contains exactly one abstract method, also referred to as Single Abstract Method (SAM) interface.
• Key Event: Triggered by pressing, releasing, or typing keys; access key code using the getCode() method.
• Mouse Event: Triggered by mouse actions; use getButton() to determine which mouse button was pressed.

Observable and Listeners

• Observable objects can add listeners using addListener(InvalidationListener listener).
• Listeners are notified upon property value changes, implementing the InvalidationListener interface to handle updates.

Animation in JavaFX

• The abstract Animation class underpins JavaFX animation functions.
• Specialized classes like PathTransition, FadeTransition, and Timeline implement specific animation behaviors.

Events and Programming Paradigms

• Event: A signal indicating an occurrence, such as mouse input or keystrokes; programs can choose to respond or ignore.
• Event-Driven Programming: User interactions drive program execution in Java GUI applications.
• Event Object: Encapsulates relevant event properties; utilize getSource() in EventObject to identify the source of events.

Compiling Inner Classes

• An anonymous inner class is compiled into a class named following the format OuterClassName$n.class.
• Constructors for anonymous inner classes default to their superclass's no-arg constructor.