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Questions and Answers
What is the root class for JavaFX event classes?
What is the root class for JavaFX event classes?
What must the handler object's class implement in JavaFX?
What must the handler object's class implement in JavaFX?
The corresponding event-handler interface.
What method is used to handle an event in JavaFX?
What method is used to handle an event in JavaFX?
handle(T e)
What is the purpose of registration methods in JavaFX?
What is the purpose of registration methods in JavaFX?
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What is an inner class in Java?
What is an inner class in Java?
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What is a functional interface?
What is a functional interface?
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What is fired whenever a key is pressed in JavaFX?
What is fired whenever a key is pressed in JavaFX?
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What is fired when a mouse button is pressed?
What is fired when a mouse button is pressed?
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What defines an observable object in JavaFX?
What defines an observable object in JavaFX?
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What class provides core functionalities for animations in JavaFX?
What class provides core functionalities for animations in JavaFX?
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What is an event in programming?
What is an event in programming?
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___ driven programming is a programming paradigm where events drive execution.
___ driven programming is a programming paradigm where events drive execution.
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What method can be used to identify the source object of an event?
What method can be used to identify the source object of an event?
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Study Notes
JavaFX Event System
- Root class for events is
javafx.event.Event
, a subclass ofjava.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 thehandle(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
, andTimeline
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()
inEventObject
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.
Studying That Suits You
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Description
Test your knowledge with these flashcards from Chapter 15 of Java FX. This chapter covers the fundamental concepts of event handling, including the root class for event classes and handler classes. Perfect for reviewing key terms and definitions related to Java FX events.