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What does GUI stand for in the context of computer programming?
What does GUI stand for in the context of computer programming?
Graphical User Interface
What does the term "event" describe in the context of programming?
What does the term "event" describe in the context of programming?
A change in the state of an object.
Provide three examples of events in a GUI program.
Provide three examples of events in a GUI program.
Pressing a button, entering a character in a text box, Clicking or dragging a mouse.
Which of the following is NOT an example of an event source in Java?
Which of the following is NOT an example of an event source in Java?
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Which event type is generated when a mouse button is clicked or released?
Which event type is generated when a mouse button is clicked or released?
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What is the purpose of an event listener in Java programming?
What is the purpose of an event listener in Java programming?
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The ActionListener interface is used to handle events related to keyboard input.
The ActionListener interface is used to handle events related to keyboard input.
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The MouseListener interface enables us to detect mouse movements and button clicks.
The MouseListener interface enables us to detect mouse movements and button clicks.
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The ItemListener interface handles changes in the state of checkboxes or list items.
The ItemListener interface handles changes in the state of checkboxes or list items.
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What is the purpose of adapter classes in Java event handling?
What is the purpose of adapter classes in Java event handling?
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What is the primary advantage of using adapter classes in Java event handling?
What is the primary advantage of using adapter classes in Java event handling?
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Study Notes
Event Handling in Java
- Event handling is a mechanism used to control events and determine actions to take after an event occurs
- Java follows the Delegation Event model for handling events
- Event handling using a GUI requires an interface-driven approach
- Events describe a change in the state of an object
Event Types
- Foreground Events: User interactions like clicking buttons, scrolling, or cursor movement
- Background Events: Operating system events like failures, interrupts, or completion of an operation
Components of Event Handling
- Events: A change in the state of an object
- Event Source: An object that triggers an event. Examples include buttons, checkboxes, list items, and more
- Listeners: Objects that react to the event. Listeners are notified when an event occurs
Important Event Classes
- ActionEvent: Generated when a button is pressed, a menu item is selected, or a list item is clicked.
- MouseEvent: Generated when the mouse is dragged, moved, clicked, pressed, released, enters, or exits a component.
- KeyEvent: Generated when a keyboard input occurs.
- ItemEvent: Generated when a check-box or list item is clicked.
- TextEvent: Generated when the value of a text area or text field changes.
- MouseWheelEvent: Generated when the mouse wheel is moved.
- WindowEvent: Generated when a window is activated, deactivated, minimized (iconic), restored (deiconified), closed, etc
- ComponentEvent: Generated when a component's state changes
- ContainerEvent: Generated when a component is added to or removed from a container
- AdjustmentEvent: Generated when adjustments occur in scroll bars.
Listener Interface
- A listener is an object that responds to events. It defines methods that handle events caused by the event source.
- Different listener types handle various kinds of events like ActionListeners, MouseListeners, KeyListeners, ItemListeners, and more.
How events are handled?
- A source generates an event and sends it to one or more registered listeners.
- Listeners process the event and return the result.
Example of Event Handling
- Java programs handle events using the
java.awt.eventpackage. - Developers need to import relevant classes like
java.awt.event.*orimport javax.swing.*and create listener objects to handle events. - Methods are associated with handling events specific to each component
Adapter Classes
- Adapter classes provide default implementations of listener interfaces
- They simplify event handling by not obligating developers to implement every method of the listener interface
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Description
Explore the critical concepts of event handling in Java, including the Delegation Event model and the types of events. Learn about the components involved, such as event sources and listeners, as well as important event classes. This quiz is designed to help solidify your understanding of GUI event handling in Java.
