Java Applets and Event Handling Quiz

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Questions and Answers

Which command is used to compile the HelloWorldApplet.java file?

javac RunHelloWorld.html

javac HelloWorldApplet.java (correct)

java HelloWorldApplet.java

appletViewer HelloWorldApplet.java

What must be done before running an applet with appletViewer?

Convert the applet to an executable file

Create an HTML file named RunHelloWorld.html

Install the appletViewer tool

Compile the applet source code (correct)

What is the correct tag structure for passing parameters to an applet in HTML?

<param name='paramName' value='paramValue'> (correct)

What is the purpose of the paint() method in the MyApplet class?

To draw graphics on the applet window Signup and view all the answers

Which statement accurately describes the use of appletViewer?

AppletViewer executes applets embedded in HTML files. Signup and view all the answers

What is the primary role of an event listener in event handling?

To receive notifications and process events when they occur. Signup and view all the answers

Which class is specifically used to register a listener for Action Events?

ActionListener Signup and view all the answers

What is an example of an event that can be generated?

Pressing a key on the keyboard. Signup and view all the answers

What must an event source do to notify event listeners?

It must register a listener to receive notifications. Signup and view all the answers

Which of the following interfaces provides methods for handling mouse motion events?

MouseMotionListener Signup and view all the answers

Which component is NOT considered an event source?

MouseEvent Signup and view all the answers

Which statement best defines event handling?

The mechanism that controls events and executes corresponding actions. Signup and view all the answers

What type of event is an ActionEvent?

An event triggered by user actions like button clicks. Signup and view all the answers

What method in the MouseListener interface is invoked when the mouse is clicked on a component?

mouseClicked(MouseEvent e) Signup and view all the answers

What is the primary function of a JComboBox in a Swing application?

It displays a drop-down list for selecting a single value. Signup and view all the answers

Which interface is used to handle mouse events such as clicks and presses?

MouseListener Signup and view all the answers

Which method in the WindowListener interface is called when a window is closed by the user?

windowClosed(WindowEvent e) Signup and view all the answers

Which container is classified as a heavyweight container in Swing?

JFrame Signup and view all the answers

How does a JPasswordField differ from a JTextField?

JPasswordField is specialized for password entry. Signup and view all the answers

Which of the following methods is used in the KeyListener interface to detect when a key is released?

keyReleased(KeyEvent e) Signup and view all the answers

What does the method mouseEntered(MouseEvent e) do?

Invoked when the mouse enters a component Signup and view all the answers

Which statement accurately describes the role of Layout Managers in Swing?

They arrange components within a frame in a specified order. Signup and view all the answers

Which interface is notified whenever the state of a checkbox changes?

ItemListener Signup and view all the answers

What is the purpose of using inner classes in Java?

To logically group classes and interfaces Signup and view all the answers

Which method from the MouseListener interface is used when the mouse button is released?

mouseReleased Signup and view all the answers

What is the main purpose of a JDialog in a Swing application?

To gather input from the user in a separate top-level window. Signup and view all the answers

When is the method windowDeiconified(WindowEvent e) invoked?

When the window is changed from minimized to normal. Signup and view all the answers

What does the method mouseExited(MouseEvent e) signify?

The mouse has exited a component. Signup and view all the answers

Which statement illustrates the function of mouseDragged(MouseEvent e)?

It is invoked when the mouse is dragged. Signup and view all the answers

In the context of Swing, which component serves to organize several other components together?

JPanel Signup and view all the answers

Which of the following describes the difference between JRadioButton and JCheckBox?

JRadioButton allows only one selection from a group, while JCheckBox permits multiple selections. Signup and view all the answers

Which method should you implement to handle mouse dragging events?

mouseDragged(MouseEvent e) Signup and view all the answers

What happens when the mouseExited(MouseEvent e) method is triggered?

A message indicates the mouse has exited the component. Signup and view all the answers

Which of the following methods is exclusively related to keyboard input?

keyPressed(KeyEvent e) Signup and view all the answers

What is the significance of using JWindow in Swing?

It is a low-level container with no borders or title, useful for pop-ups. Signup and view all the answers

What is required in a MouseEventEx class to handle mouse events?

It must implement the MouseListener interface. Signup and view all the answers

In which package are MouseListener and MouseMotionListener interfaces found?

java.awt.event Signup and view all the answers

What is a characteristic of a member inner class?

It can have access modifiers like public and private. Signup and view all the answers

Which statement is true about local inner classes?

They must be instantiated in the method where they are defined. Signup and view all the answers

What is the purpose of an anonymous inner class?

To implement an interface or extend a class without naming it. Signup and view all the answers

What distinguishes static nested classes from non-static nested classes?

Static nested classes cannot access instance variables of the outer class directly. Signup and view all the answers

Which statement about local inner class access is correct?

It cannot be accessed outside the method where it is defined. Signup and view all the answers

Which of the following is NOT a type of nested class in Java?

Macro inner class Signup and view all the answers

What is required for an anonymous inner class declaration?

The use of the keyword new. Signup and view all the answers

What is a feature of member inner classes?

They can access members of the outer class including private members. Signup and view all the answers

Study Notes

Java Programming

James Gosling is credited with developing Java.

GUI Programming with Swing

Swing is a part of Java Foundation Classes (JFC) used for creating window-based applications.
It's built on top of Abstract Window Toolkit (AWT).
Swing provides platform-independent and lightweight components.
Swing uses the Model-View-Controller (MVC) architectural pattern.
The javax.swing package contains various classes for creating Swing components.
- JButton, JTextField, JTextArea, JRadioButton, JCheckBox, JMenu, JColorChooser.

AWT

AWT stands for Abstract Window Toolkit.
It's a platform-dependent API for developing graphical user interfaces (GUIs) in Java.
AWT components are platform-dependent, meaning their appearance and behavior might differ across operating systems (Windows, macOS, Unix).
AWT components are heavyweight, meaning they consume more system resources.
AWT has limitations in terms of platform independence, performance, and the availability of components.

Limitations of AWT

AWT components are heavyweight, consuming more system resources.
AWT components are platform-dependent.
AWT programs can increase the overhead on the Java Virtual Machine (JVM).
Buttons in AWT do not support images.
Important components like tables and trees are missing.

Java Foundation Classes (JFC)

JFC is a set of GUI components that simplify the development of desktop applications.
JFC components are lightweight and use minimal system resources.
JFC components maintain a consistent look and feel across different platforms.

Swing Features

Lightweight: Swing components are lightweight and use minimal system resources.
Platform-Independent: Swing components are designed to work on various platforms with consistent looks and feels.
Rich Controls: Swing provides a wide range of advanced controls, including tables, sliders, color pickers, and trees.
Highly Customizable: Swing components can be customized easily to meet visual requirements.
Pluggable Look-and-Feel: Swing allows developers to change the look and feel (appearance) of components at runtime.

Swing Class Hierarchy

The Swing components are organized in a hierarchical structure starting with the Object class, going through Component, Container, JComponent, and their subclasses, such as JLabel, JButton, JList, etc.

Difference Between AWT and Swing

AWT components are heavyweight, Swing components are lightweight.
AWT is slower than Swing in terms of performance.
AWT needs more memory than Swing.
AWT is platform-dependent, Swing is platform-independent.
AWT provides fewer components than Swing.

Swing Components

JLabel: Used for displaying text or images in a container.
JButton: Used to create clickable buttons.
JTextField: Used for single-line text input.
JTextArea: Used for multi-line text input.
JList: Displays a list of items that can be selected.
JScrollBar: Represents the horizontal and vertical scroll bars of a component.
JComboBox: A dropdown list where users can select an item.
JCheckBox: A clickable checkbox for selecting an option.
JRadioButton: A clickable radio button used for selecting one option from a group.
JSlider: Allows users to select a value by dragging a slider.
JTable: Used for displaying data in table format.
JMenu: Used to create a menu item.
JMenuBar: Used for displaying menus.
JPasswordField: A password text field that doesn't display entered text.
JPanel: A container for grouping components.
JFrame: A top-level window.
JWindow: Provides a dialog which does not have a border, title or titlebar.
JDialog: A top-level window used for displaying a dialog.
JScrollPane: A container providing the ability to scroll the contents of a component.

Layout Managers

Layout managers control the arrangement, size, and position of components within a container.
- FlowLayout: Arranges components in a row, left-to-right.
- BorderLayout: Arranges components in five locations (north, south, east, west, center).
- CardLayout: Arrange components as a stack of cards, displaying one at a time.
- GridLayout: Organizes components into equal-sized rectangles on a grid.
- GridBagLayout: A more flexible layout manager allowing components to span multiple cells on a grid, and control placement based on defined constraints.

Inner Classes

A class defined inside another class is called an inner class or nested class.
- Member inner classes: Defined directly within an outer class.
- Local inner classes: Defined within a method.
- Anonymous inner classes: Created without a name; used once, typically to implement interfaces.

Applet

An applet is a special type of Java program designed to be embedded in a web page.
Applets run within a web browser at the client-side.
Applets can perform various actions, such as displaying graphics, playing sound, and performing calculations.

Applet Life Cycle Methods

init(): Initializes the applet. Called only once.
start(): Starts the applet. Called after init.
paint(): Paints the applet's content.
stop(): Stops the applet.
destroy(): Releases resources when the applet is terminated.

Passing Parameters to Applet

Parameters provide extra information to an applet from an HTML page.
Parameters are specified within the <applet> tag using the <param> tag, referencing both the parameter's name and its corresponding value.

Event Delegation Model

The modern approach for handling events in GUI applications.
Events are generated by a source and forwarded to one or more listeners, separating the actions from the user interface. This creates a layered approach to processing events.

Event Listeners

Interfaces acting as listeners to events.
- ActionListener: Listens to general action events (buttons, menus). MouseListener: Listens to mouse events (clicks, rolls, movement). WindowListener: Listens to window events (opening, closing, activating, deactivating).

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Description

Test your knowledge on Java applets and event handling concepts through this insightful quiz. Questions cover topics such as the applet lifecycle, event listeners, and specific methods used in Java applet programming. Perfect for students learning Java programming and applet development.