Event Driven/GUI Programming Week 1

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 Abstract Window Toolkit

the package provides classes for this word 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

Components are platform independent

Swing

Components are lightweight

Swing

Supports pluggable look and feel

Swing

Provides more powerful components

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 (number)
The user performs an action on the interface

2

MVC Control Flow (number)
The controller takes the input event

3

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

4

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

5

MVC Control Flow (number)
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