Event Driven/GUI Programming Week1-2

Non-GUI applications

console based

Non-GUI applications

application has control at all stages of execution

Non-GUI applications

user's interaction with the application is pre-programmed

Non-GUI applications

application calls to the OS to execute built in language modules

GUI Applications

Application that is windows/forms-based

GUI Applications

non-sequential program execution

GUI Applications

Event Driven

Event Driven

Application sits in a process loop waiting for an event to occur/execute

GUI Applications

Application receives message from the OS that an event has occurred

Event

a notification from the OS that an action has occurred

Event

this needs to be registered to work

Event Handler

methods that tell what should be done when an event occurs

Event Handler

their order of executions differ in every program execution

Event-Driven Programming

It involves a new type of flow-of-controls - events

Event-Driven Programming

It is asynchronous. They manifest themselves by altering the state of the execution environment. They are detected through this change.

Control Structure is inverted

system has control, not the application

System

It waits for an event then calls the appropriate routine in the application

a set of classes (widgets)

they can detect user's input

listeners or event handlers

define what the system will do in response to an event

Java Foundation Classes (JFC)

a set of GUI components for Java applications

Java Foundation Classes (JFC)

encompasses a group of features for building Graphical User Interface (GUI)

Java Foundation Classes (JFC)

adds rich graphics functionality and interactivity to Java Applications

Features of
Java Foundation Classes (JFC)

-Swing GUI Components
-Pluggable Look-and-Feel Support
-Accessible API
-Java 2D API
-Internalization

Java Abstract Window Toolkit

an API to develop GUI or window-based applications in Java

java.awt

the package provides classes such as Text Field, Label, TextArea, RadioButton, CheckBox, Choice, List, etc.

Java Abstract Window Toolkit

Maps general Java code to each operating system's real GUI System

Java Swing

part of Java Foundation Classes (JFC) that is used to create window-
based applications

Java Swing

built on the top of AWT (Abstract Windowing Toolkit) API and entirely written in java

Java Swing

Paints GUI controls itself pixel-by-pixel rather than handing off to OS.

Java Swing

Unlike AWT, it provides platform-independent and lightweight components.

Java Swing

package provides classes for it such as JButton, JTextField, JTextArea, JRadioButton, JCheckbox, JMenu, JColorChooser etc

AWT

AWT vs Swing:
Components are platform dependent

AWT

AWT vs Swing:
Components are heavyweight

AWT

AWT vs Swing:
Doesn’t support pluggable look and feel

AWT

AWT vs Swing:
Provides less components than Swing

AWT

AWT vs Swing:
Doesn’t follow MVC design architecture

Swing

AWT vs Swing:
Components are platform independent

Swing

AWT vs Swing:
Components are lightweight

Swing

AWT vs Swing:
Supports pluggable look and feel

Swing

AWT vs Swing:
Provides more powerful components

Swing

AWT vs Swing:
Follows MVC design architecture

Model-View-Controller Pattern

Software architecture pattern that separates the model, the user- interface and control logic of an application in three distinct components

Model

(MVC)
Representation of domain data

Model

(MVC)
Business logic

Model

(MVC)
Persistence mechanism

View

(MVC)
User interface

View

(MVC)
Interaction elements

Controller

(MVC)
Intermediary between the Model and View

Controller

(MVC)
Maps user actions to model actions

Benefits of MVC

• Organization
• Rapid Application Development
• Code reuse
Parallel development
• Presents the same information in different ways
• The views and application behavior should reflect the manipulations of data immediately
• Allows different user interface standards or port it to other environments where the application codes should not be affected.

1

MVC Control Flow (1-5)
The user performs an action on the interface

2

MVC Control Flow (1-5)
The controller takes the input event

3

MVC Control Flow (1-5)
The controller notifies the user action to the model which may involve a change of the model’s state

4

MVC Control Flow (1-5)
It generates a new view. The view takes the data model.

5

MVC Control Flow (1-5)
The user interface waits for another user interaction, which starts a new cycle.

Model

MVC and Java GUI
• made by the programmer/developer

View

MVC and Java GUI
• set of objects of classes that inherit from java.awt.Component

Controller

MVC and Java GUI
• The event processing thread which captures and propagates the event to the view and model.

Controller

MVC and Java GUI
• Uses classes of events that implement EventListener type interfaces (e.g.
ActionListener)

Window

Java GUI Application Components
• The top-level container.
• Examples: frame, dialog box

Component/Control

Java GUI Application Components
• A GUI widget that resides in a window.
• Examples: button, text box, label

Container

Java GUI Application Components
• A logical grouping for storing components.
• Examples: panel, box

JLabel

The class can display either text, an image, or both.

Display

Label's contents are aligned by setting the vertical and horizontal alignment in its ____ area

vertically centered

By default, labels are ______ in their display area

Text-only

____ labels are leading edge aligned by default

image-only

_____ labels are horizontally centered by default

JButton

an implementation of a push button

JToggleButton

a two-state button typically used on toolbars to indicate the state of a toggleable (on/off) option, such as the bold, italic and underline font attributes that are enabled when using a word processor

Imagelcon

an implementation of the Icon interface that paints Icons from Images

JTextField

a component which allows the editing of a single line of text.

JPassword Field

a component which is specialized to handle password functionality and allows the editing of a single line of text.

JTextArea

a multi-line area to display plain text

Events

______ are generated as a result of user interaction with the graphical user interface components such as clicking on a button, moving the mouse, entering a character through keyboard, selecting an item from the list, etc

Event Handling

is the mechanism that controls the event and decides what should happen if an event occurs.

Event Handler

This mechanism has a code which is known as an ______, that is executed when an event occurs.

Delegation Event Model

Java uses the _______ to handle the events. This model defines the standard mechanism to generate and handle the events

Foreground Events

These events require direct interaction of the user.

Foreground Events

These events are generated as consequences of a person interacting with the graphical components in the Graphical User Interface

Background Events

These events require indirect interaction of the end user

Background

Operating system interrupts, hardware or software failure, timer expiration, and operation completion are some examples of _______ events

Foreground

clicking on a button, moving the mouse, entering a character through keyboard, selecting an item from list, scrolling the page are some examples of _____ events

Source

_____ is an object on which the event occurs

Source

responsible for providing information of the occurred event to it's handler

Listener

It is also known as event handler

Listener

responsible for generating a response to an event

Listener

________ is an object that waits until it receives an event. Once the event is received, the ________ processes the event and then returns (one word)

Listener

In this model, the ______ needs to be registered with the source object so that the listener can receive the event notification

ActionEvent

Is generated when button is clicked or the item of a list is double-clicked

KeyEvent

On entering the character the ______ is generated

MouseEvent

This event indicates that a mouse action occurred in a component. This low-level event is generated by a component object for Mouse Events and Mouse motion events

WindowEvent

This low-level event is generated by a Window object when it is opened, closed, activated, deactivated or when the focus is transferred into or out of the Window

MouseMotion Event

indicates a mouse action occurred in a component. This low-level event is generated by a component object when a mouse is dragged or moved

PaintEvent

The object of this class represents the change in the state of a window

EventListener

represent the interfaces responsible to handle events

EventListener

It is a marker interface which every listener interface has to extend.

EventListener

This class is defined in java.utiI package

ActionListener

used for receiving the action events

ItemListener

used for receiving the item events

KeyListener

used for receiving the key events