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Questions and Answers
Which method is utilized to change the location of an event?
Which method is utilized to change the location of an event?
Which constant is part of the TextEvent class representing a text value change?
Which constant is part of the TextEvent class representing a text value change?
Which method allows you to obtain the object generating a Window Event?
Which method allows you to obtain the object generating a Window Event?
What is the superclass of the WindowEvent class?
What is the superclass of the WindowEvent class?
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Which interface includes the method actionPerformed()?
Which interface includes the method actionPerformed()?
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Which statement accurately describes when an event is generated?
Which statement accurately describes when an event is generated?
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Which method should be used to remove an event listener in Java?
Which method should be used to remove an event listener in Java?
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Identify the class located at the root of Java's event hierarchy.
Identify the class located at the root of Java's event hierarchy.
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What integer constant does the TextEvent define?
What integer constant does the TextEvent define?
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FocusEvent is a subclass of which event class?
FocusEvent is a subclass of which event class?
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Which of the following is not considered an event source?
Which of the following is not considered an event source?
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When is the InputEvent not generated?
When is the InputEvent not generated?
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Which interface is specifically designed for handling checkbox events?
Which interface is specifically designed for handling checkbox events?
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What is the appearance characteristic of a push button?
What is the appearance characteristic of a push button?
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Which method is defined by the ItemListener interface to indicate a change in item state?
Which method is defined by the ItemListener interface to indicate a change in item state?
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In the Delegation Event Model, what is the role of a listener?
In the Delegation Event Model, what is the role of a listener?
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What characteristic defines a label in a GUI?
What characteristic defines a label in a GUI?
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Which sequence correctly describes the order of events generated by KeyEvent?
Which sequence correctly describes the order of events generated by KeyEvent?
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Which method is not part of the MouseListener interface?
Which method is not part of the MouseListener interface?
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What is an anonymous inner class in Java?
What is an anonymous inner class in Java?
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How many listeners can a source send an event to in the Delegation Event Model?
How many listeners can a source send an event to in the Delegation Event Model?
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What characterizes an anonymous inner class?
What characterizes an anonymous inner class?
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What package contains all the classes needed for event handling in Java?
What package contains all the classes needed for event handling in Java?
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What defines an event in the delegation event model in Java?
What defines an event in the delegation event model in Java?
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Which method is utilized to register a keyboard event listener in Java?
Which method is utilized to register a keyboard event listener in Java?
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What type of listener is notified when a mouse motion event occurs?
What type of listener is notified when a mouse motion event occurs?
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What is the role of a listener in event handling?
What is the role of a listener in event handling?
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Which library defines the Event class in Java?
Which library defines the Event class in Java?
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Which method can be used to determine the source of an event?
Which method can be used to determine the source of an event?
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What is the superclass of all event classes in Java?
What is the superclass of all event classes in Java?
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Which event is generated when a scrollbar is manipulated?
Which event is generated when a scrollbar is manipulated?
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Which method is used to find out the degree of adjustment made by the user?
Which method is used to find out the degree of adjustment made by the user?
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What does the KeyListener interface provide?
What does the KeyListener interface provide?
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Which constant value changes when the scrollbar is clicked to increase its value?
Which constant value changes when the scrollbar is clicked to increase its value?
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What event is generated when the size of a component changes?
What event is generated when the size of a component changes?
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Which event is triggered when a component is added or removed?
Which event is triggered when a component is added or removed?
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Which method retrieves the reference to the container that caused a ContainerEvent?
Which method retrieves the reference to the container that caused a ContainerEvent?
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Which constant indicates that the vertical scrollbar should always be displayed?
Which constant indicates that the vertical scrollbar should always be displayed?
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Which method handles the WindowsClosing event?
Which method handles the WindowsClosing event?
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When input focus is gained or lost, which event type is generated?
When input focus is gained or lost, which event type is generated?
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Study Notes
Event Handling in Java
- Event: An object that describes a state change in a source. Events are generated by user interactions or internal state changes.
- Event Source: An object that generates an event. Examples include buttons, text fields, and menus.
- Event Listener: An object that handles an event. It's registered with the event source. A listener is usually an object meant to receive and process events generated from an event source.
Event Hierarchy
- java.util.EventObject: The superclass of all event objects. It contains the source of the event.
- java.awt.Event: An older class part of the Abstract Window Toolkit (AWT). This is part of an older event handling model.
- java.awt.AWTEvent: An older class part of AWT used for events, particularly those generated for GUI components. It represents the root of the AWT event hierarchy.
- java.awt.EventObject: An older class part of AWT used for events.
Event Handling Mechanisms
- Delegation Event Model: A modern event handling model in Java. An event source notifies one or more listeners when an event occurs. Listeners respond to these events. The event is sent to all registered listeners.
Events and Sources
- Action Events: Generated when an action occurs. Examples include button presses, menu selections.
- Focus Events: Generated when components gain or lose focus.
- Text Events: Generated in response to text changes in text fields or text areas.
- Window Events: Generated when a window is opened, closed or gains or loses focus.
- KeyListener: Responsible for handling keyboard events. Registered for an element.
- MouseListener: Handles mouse events registered for an element.
- MouseMotionListener: Handles mouse motion events like dragging, moving the mouse.
- AdjustmentListener: Called when the position of a scroll bar is adjusted.
- ItemListener: Called when an item in a list, menu, or combo box is selected or deselected.
Other Important Concepts
-
Listener Interfaces: Interfaces defining methods for handling specific types of events. Example interfaces include
ActionListener,KeyListener,MouseListener. - Anonymous Inner Classes: Classes defined within another class that are not given names (often used to create event listeners).
-
Event Handling Packages:
java.awt.eventandjava.util.EventObjectare key packages related to event handling. -
Constants:
java.awt.eventcontains constants for different event types and conditions (e.g.,ActionEvent.CTRL_MASK). -
Event Handling Methods: Particular methods are used to handle events. (
actionPerformed,mouseClickedetc)
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Description
This quiz covers the fundamentals of event handling in Java, including event objects, event sources, and event listeners. Understand the event hierarchy and different mechanisms involved in processing events generated by user interactions and internal state changes. Test your knowledge of Java's event handling framework.
