Object Oriented Programming Concepts Analysis + Design

What’s in store… Real world problems  software solution Functionality – Requirements/Use-cases Object Oriented [OO] Concepts Unified Modeling Language [UML] Simple Design Pattern

Real world problems  software solution

Functionality – Requirements/Use-cases

Object Oriented [OO] Concepts

Unified Modeling Language [UML]

Simple Design Pattern

Real World Problems  Software Solutions 1. Functionality - The code should do what it’s supposed to do 2. Analysis and Design - Application of basic OO concepts 3 . Frameworks & Design Patterns – Strive for a maintainable and scalable solution

1. Functionality - The code should do what it’s supposed to do

2. Analysis and Design - Application of basic OO concepts

3 . Frameworks & Design Patterns – Strive for a maintainable and scalable solution

Functionality – Requirements & Use-cases Requirements set out the final expectations from the system Use-case enumerates in detail the steps the system should take Use-case has a single goal Every use-case has a start and stop condition, an external initiator and clear value

Requirements set out the final expectations from the system

Use-case enumerates in detail the steps the system should take

Use-case has a single goal

Every use-case has a start and stop condition, an external initiator and clear value

Functionality – Requirements & Use-cases A B C … UC 1 UC 2 UC 4 UC2 UC3 UC4 UC1 UC4 UC5 UC6 Requirements

A

B

C

…

UC 1

UC 2

UC 4

UC2

UC3

UC4

UC1

UC4

UC5

UC6

OO Concepts Everything is an Object Everything consists of objects

Everything is an Object

Everything consists of objects

OO Concepts – I N H E R I T A N C E Build classes based on other classes Avoid duplicating and repeating Inherit behaviour and change [ override ] if required Sub-class should be substitutable for parent class

Build classes based on other classes

Avoid duplicating and repeating

Inherit behaviour and change [ override ] if required

Sub-class should be substitutable for parent class

OO Concepts – P O L Y M O R P H I S M Change behaviour without changing code Allows a sub-class to stand-in for another class

Change behaviour without changing code

Allows a sub-class to stand-in for another class

OO Concepts – E N C A P S U L A T I O N Protect information in your code from being used incorrectly Object = state + behaviour Also known as Information Hiding or Separation of Concerns Duplicate code is an indicator

Protect information in your code from being used incorrectly

Object = state + behaviour

Also known as Information Hiding or Separation of Concerns

Duplicate code is an indicator

OO Concepts – C O M P O S I T I O N Loose coupling between objects Greater flexibility Code changes don’t lead to cascading code breakage Better encapsulation

Loose coupling between objects

Greater flexibility

Code changes don’t lead to cascading code breakage

Better encapsulation

Unified Modeling Language – U M L Purely representational Programming language independent A notational set based language and NOT a methodology Fits easily into any company’s way of functioning Conveys information through a wide set of diagrams Use-case diagram Class diagram Sequence diagram State-chart diagram Activity diagram Component diagram

Purely representational

Programming language independent

A notational set based language and NOT a methodology

Fits easily into any company’s way of functioning

Conveys information through a wide set of diagrams

Use-case diagram

Class diagram

Sequence diagram

State-chart diagram

Activity diagram

Component diagram

U M L – Use-Case Diagram Illustrates a unit of functionality Helps visualize functional requirements of a system Include relationships of actors [users] to processes

Illustrates a unit of functionality

Helps visualize functional requirements of a system

Include relationships of actors [users] to processes

U M L – Class Diagram Shows the static structures and relationships of a system Can be used to display logical groupings/classifications Also used to depict implementation classes Both the state and behaviour of classes captured Relationships between classes also important

Shows the static structures and relationships of a system

Can be used to display logical groupings/classifications

Also used to depict implementation classes

Both the state and behaviour of classes captured

Relationships between classes also important

U M L – Sequence Diagram Depicts in detail the flow of control through a use-case Consists of 2 dimensions – Horizontal – shows sequence of calls/messages in time order of occurrence Vertical – the object instances to which messages are sent Sequence of flow starts at the top left corner

Depicts in detail the flow of control through a use-case

Consists of 2 dimensions –

Horizontal – shows sequence of calls/messages in time order of occurrence

Vertical – the object instances to which messages are sent

Sequence of flow starts at the top left corner

A Design Pattern – D E L E G A T I O N An object outwardly exhibits a behaviour – which is performed by another object Better encapsulation Impact of code changes minimised Sometimes referred to as aggregation Example – A stack built on top of a list

An object outwardly exhibits a behaviour – which is performed by another object

Better encapsulation

Impact of code changes minimised

Sometimes referred to as aggregation

Example – A stack built on top of a list

So, WHAT MAKES GOOD CODE?

References UML Basic: An Introduction [IBM] Head First - Object Oriented Analysis and Design Wikipedia

UML Basic: An Introduction [IBM]

Head First - Object Oriented Analysis and Design

Wikipedia