02-CCFP4.0_OOP Using Java

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OO programming using Java

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Copyright 2013-2014, Infosys Limited ConfidentialConfidential

Copyright Guideline

2013 Infosys Limited, Bangalore, India. All Rights Reserved.

Infosys believes the information in this document is accurate as of its publication date; such

information is subject to change without notice. Infosys acknowledges the proprietary rights of

other companies to the trademarks, product names and such other intellectual property rights

mentioned in this document. Except as expressly permitted, neither this documentation nor

any part of it may be reproduced, stored in a retrieval system, or transmitted in any form or by

any means, electronic, mechanical, printing, photocopying, recording or otherwise, without the

prior permission of Infosys Limited and/ or any named intellectual property rights holders

under this document.

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Confidential Information

This Document is confidential to Infosys Limited. This document contains information and data that

Infosys considers confidential and proprietary (Confidential Information).

Confidential Information includes, but is not limited to, the following:

Corporate and Infrastructure information about Infosys

Infosys project management and quality processes

Project experiences provided included as illustrative case studies

Any disclosure of Confidential Information to, or use of it by a third party, will be damaging to Infosys.

Ownership of all Infosys Confidential Information, no matter in what media it resides, remains with

Infosys.

Confidential information in this document shall not be disclosed, duplicated or used in whole or in part

for any purpose other than reading without specific written permission of an authorized representative of

Infosys.

This document also contains third party confidential and proprietary information. Such third party

information has been included by Infosys after receiving due written permissions and authorizations fromthe party/ies. Such third party confidential and proprietary information shall not be disclosed, duplicated

or used in whole or in part for any purpose other than reading without specific written permission of

an authorized representative of Infosys.

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Course Information

Course Code: CCFP4.0-OOP

Course Name: OO programming using Java

Document Number: OOP-02

Version Number: V4.0

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Recap

Topics covered on Programming Fundamentals

Problem Solving skills

Identifiers

Variables

Data types

Declaration of variables

Operators

Control Structures

Type casting and conversion

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OO Fundamentals


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OO Fundamentals - Topics SDLC Overview

OO Concepts

Introduction to UML

OO Fundamentals Implementation in Java

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A peek into history..

8

Why do you

think the

ship sank?


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A system engineers story.

Now lets listen to a software engineering story

Roy, a system engineer, in Infosys has something to tell youRead on

To summarize, for Roy and team to go ahead with the application development,

they need

An engineering approach towards application development like SDLC (Software

Development Life Cycle)

To address the challenges and develop the business application

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Guided Activi ty: Programming Fundamentals-Part II - Assignment 21


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Software Development LifecycleOverview


anywhere!


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Software Development Lifecycle (SDLC) Overview

Phases of software development

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SystemEngineering

Requirementsanalysis

Design Development Test Deploy

Scope of the project is defined

User requirements are

gathered

Requirements are analyzed

Software Requirements

Specification (SRS) document is

created

Design is created based on

requirements

High level design document and

Detail level design document are

created

Code is developed based on

design

Unit testing is done on the

code

Integration and system testing areperformed

Acceptance Testing is done by the

client/customer

As a system engineer, you will be contributing mainly to

this phase and this course will also be focusing on this

phase of SDLC


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Need for Object OrientedApproach


anywhere!


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Need for Object Oriented Approach

Challenges in developing a business application

Integration of modules/applications

Extensibility of existing code

High level of flexibility and illusion of simplicity

If these challenges are not addressed it may lead to Software Crisis

Features needed in the business application to meet these challenges:

Modularity, Extendibility, Reusability, Interoperability, Security

Challenges can be addressed using object oriented approach

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Need for Object Oriented Approach

Properties of a business application

Clear separation of functionalities

Exhibits hierarchy

Composed of subsystems

These properties can be implemented using object oriented approach

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Easy Shop application is a complex business application & object oriented approach may

be used to develop this system

Road Ahead - Need to understand object oriented concepts


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Object Oriented Concepts


anywhere!


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Classes & Objects (1 of 2)

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Customer Id:

1001

Customer Name:

Cameron

Telephone Number:

9901911445

Address:No.31, Silver Shine,Bangalore, India

Customer Id:

1002

Customer Name:

Alphonso

Telephone Number:

9496244655

Address:No.255, Brigade,Bangalore, India

Values of

attributes of

Customer

Attributes of

Customer

Cameron & Alphonso are

two instances

/examples/objects of Easy

Shop customers

Let us look at some customers


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Classes & Objects (2 of 2)

A class is a software design that describes the common attributes and activities

(behavior) of objects

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Example : Customer Id, Name, Telephonenumber and AddressAttributes

Activities(behavior) exhibited by theclass to external world

Example: Purchasing items from theretail shop

Behavior/Activity


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Abstraction Guided Activity

Users of the retail application Billing staff, Admin, Retail outlet manager

Each user needs to know some details and need not know other details

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ABSTRACTION : Process of identi fying the essent ial details to be known and

ignoring the non-essential detai ls from the perspective of the user of the system

Billing staff (

Billing of

customers )

Admin (Registration

of customers)Retail Outlet

Manager

(Registration of

users)

Whoaretheusersof

theretailapplication?

What

are

the

things

each

user

must

know

to

perform

their

activities?


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Encapsulation Guided Activity

Swipe machine in a retail store Used by billing staff to key the amount

Used by admin to record payment

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ENCAPSULATION : A mechanism of hiding the internal detai ls and allowing a simple

interface which ensures that the object can be used without having to know how itworks

How

is

a

swipe

machine

used

for

payment

of

bill

in

a

retail

store?


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Inheritance Guided Activity

Customers are of two kinds

Regular

Privileged

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The regular customer in addition is given discounts

All customers have Customer Id, Name, Telephone

Number and Address

RegularCustomersPrivileged

CustomersThe privileged customer gets a membership cardbased on which gifts are given

All customers have some generic features. The different kinds of customers have all

generic features in addition to some specific features

INHERITANCE : Is a mechanism which al lows to def ine general ized characteristics

and behavior and also create special ized ones. The special ized ones automat ical ly

tend to inherit al l the properties of the generic ones

What

are

the

two

different

types

of

customers

you

can

see

intheretail

application?


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Polymorphism Guided Activity

Payment of bill - Two modes

Cash (Calculation includes VAT)

Credit card(Calculation includes processing charge and VAT)

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TotalAmount=Purchaseamount+VAT+Processingcharge

TotalAmount=Purchaseamount+VAT

The activity of paying the bill is the same. But the formula for calculation of bill

differs as per the mode of payment

POLYMORPHISM: Refers to the abil ity of an object/operation to behave

differently in different situations

What

do

you

observe

in

this

retail

store

scenario?


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Object Oriented Approach Benefits

Leads to development of smaller but stable subsystems

The subsystems are resilient to change

Reduces the risk factor in building large systems as they are built incrementally

from subsystems which are stable

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Hence Object Orientation is suitable for developing extremely complex business

systems

Quiz: Object Oriented Fundamentals - Assignment 22

Road Ahead - Need to understand object oriented system development


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Introduction to UML


anywhere!


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Object Oriented System Development

Like SDLC, Object oriented approach also involves-

Object oriented analysis

Object oriented design

Object oriented programming

Testing

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Juan, the client representative, has just informed that

as first phase, the Easy Shop management, wants to

automate the purchase of items by customers and the

billing process .

CCFP4.0-Retail Application_Phase I_Problem Statement_OOP.docx


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Object Oriented System Development

Object Oriented Analysis and Design involve -

Modeling the system based on requirements

Identification of classes and relationship between them

Identification of attributes and methods

Constructing the logical and physical object models

The representation of design is done using UML

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Road Ahead - Need to understand representation of design using UML


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The Unified Modelling Language (UML)

The Unified Modelling Language (UML) is a language for visualizing, specifying,

constructing and documenting the software system and its components

[OMG03a]

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Visual

UML is a graphicallanguage

Notations of UML are

well-defined

Specify

Building models that areprecise, unambiguous

Document

Enables documentation ofsystem architecture and

details

Construct

Enables mapping from amodel in the UML to OO

Languages such as Java,C++, or C#

UML


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UML Diagrams

There are thirteen standard diagrams used in different phases

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UseCaseDiagram

Class

Diagram

ObjectDiagram

ComponentDiagram

CompositeStructureDiagram

PackageDiagram

DeploymentDiagram

State

Machine Diagram

ActivityDiagram

SequenceDiagram

Communication Diagram

TimingDiagram

Interaction OverviewDiagram

We will be focusing on use case diagrams and class diagrams in this course


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Use Case Diagram

Helps in identification of the system under development

Use-case is a technique to capture business process from the users perspective

i.e., a way of documenting system functionality expected by the user

Notations used

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Demo: CCFP4.0_Retail Application_Phase I_Use case diagram_OOP.pdf

Refer to the use case specifications provided

in the pdf


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Class Diagram

Classes are the basic components of an OO system

Class diagram shows the collection of classes and the relationships among them

A class is represented by a rectangular box with three compartments :

Class Name

Attributes

Behavior

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Demo: CCFP4.0_Retail Application_Phase I_Class Diagram_OOP.docx

Guided Activity: OO Fundamentals - Assignment 23

Links: ht tp://www.uml-diagrams.org/


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OO Fundamentals we have learnt

SDLC Overview

OO Concepts

Classes & Objects

Abstraction

Encapsulation

Inheritance

Polymorphism

Introduction to UML

Use case diagram

Class diagram

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OO Fundamentals Implementation in Java


anywhere!

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OO Fundamentals Java Implementation

Object Oriented Fundamentals

Instance Variables

Methods

Access Specifiers

Classes & Objects

Coding Standards

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Instance Variables Guided Activity

Variables used for representing the state of an object/attributes of a class are

called member variables/instance variables

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customerId

and

telephoneNo

Identifythemember

variables

of

the

Customerclass?

What

can

be

the

data

types

used

for

thesemember

variables?

customerId can

be

int and

telephoneNo can

be

long

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Access Specifiers

Used to expose or hide the attribute and behavior of a class

Used to specify the access permitted on a member

public(+)

A declaration that is accessible to all classes

Keyword used is public

private(-)

A declaration that is accessible only to the class in which it is declared

Keyword used is private

protected(#)

Keyword used is protected

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More on this access specifier will be discussed as part of

Inheritance and abstract keyword

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Methods (1 of 2)

Methods define the behavior of an object

All the methods should be defined inside the class with an access specifier

Values that are passed to methods are known as arguments/parameters

Value that is returned from a method is known as return value

A method can return only one value at a time and it can be done using the return

statement

Implementation of a method requires the following:

Method Header

Method Definition

Method Invocation/Method Call

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Detailsofpassingargumentstomethodswillbedealtlater

Methods (2 of 2)

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public voidsetCustomerId(int id){

customerId

=

id;}

public void

setTelephoneNo(long

teleNo){

telephoneNo=teleNo;

}

public intgetCustomerId(){

return

customerId

;}

publiclonggetTelephoneNo(){

returntelephoneNo;

}

Observations:

The datatype of the returnvalue matches the return

type mentioned in the

header of the method

Some methods takearguments ex.

setTelephoneNo() and some

methods do not take

arguments ex.

getTelephoneNo()

Some methods do not returnexplicit values ex.setTelephoneNo()

Return

type

Name

of

the

method

Returnvalue

Method

definition

Arguments/parameters

Accessspecifier

Methodheader

I l t ti f Cl i J G id d37


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Implementation of a Class in Java GuidedActivity

classCustomer{

privateintcustomerId;

private

long

telephoneNo;publicvoidsetCustomerId(int id){

customerId=id;

}

publicvoidsetTelephoneNo(longteleNo){

telephoneNo=teleNo;}

publicintgetCustomerId(){

returncustomerId;

}

public

long

getTelephoneNo(){returntelephoneNo;

}

}

Abstraction

&

Encapsulation

Identify

the

OO

feature

implemented

using

this

code?

instance

variables

class

How

can

this

class

be

used

to

createan

instanceofa

customer?

BycreatingobjectsofCustomerclass

methods

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Creation of Objects

Class is a blueprint for the creation of objects

To realize a class, an object or an instance of the class needs to be created

There can be many instances for a class and each instance will have its own data

In Java, the operator new allocates memory for objects during run time ie.

dynamic memory allocation

The following statement creates an object of the class Customer and returns a

reference to the newly created object

new

Customer();

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Reference Variables

The reference returned by a newly created object must be assigned to a variable

and that variable is known as reference variable

Following syntax can be used to create a reference variable for the Customer

class and make it point to a Customer object

Reference variable can be assigned null to show that it is not referring to anyobject nullisakeyword

CustomercustObj =null;

Customer

custObj =

new

Customer();

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A complete Java Program

Access Specifiers

Variables Local and Instance variables

Methods

Starter class

Creation of objects

Reference variables

Compilation and Execution of a java program



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Coding Standards


anywhere!

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Coding Standards

Set of guidelines

Enhance the readability and clarity of the program

Make it easy to debug and maintain the program

Should follow Pascal Case

First letter should be Uppercase

First letter of each internal word should be

capitalized(if it is present)

Class Name

Should follow Camel Case

First letter should be Lowercase First letter of each internal word should be

capitalized(if it is present)

Instance variable,

ReferenceVariable &

Method Name

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Bad Code versus Good Code

Bad Code Good Code

class A{

private int i;

public void methodone(int a){i=a;

}

public int methodtwo(){

return i;

}}

class Customer{

private int customerId;

public void setCustomerId(int id){customerId = id;

}

public int getCustomerId(){

return customerId;

}}


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Self-Study

1. Refer to udacity course: https://www.udacity.com/courses

Course name: Introduction to Programming in Java

Lessons: Introduction, Objects, Classes, Fundamental Data Types

3. Links: http://www.uml-diagrams.org/


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2013Infosys Limited, Bangalore, India. All Rights Reserved. Infosys believes theinformation in thisdocument is accurate as of its publication date; such information is subject to changewithout notice. Infosys acknowledgesthe proprietaryrights of other companiesto thetrademarks,product names andsuch other intellectual property rightsmentioned in this document.Exceptasexpressly permitted,neither thisdocumentation nor anypart of it maybe reproduced,stored in a retrievalsystem,or transmittedin anyform or by anymeans, electronic, mechanical,printing,photocopying,recordingor otherwise,withoutthe prior permissionof Infosys Limitedand/or anynamedintellectual property rightsholdersunderthis document.

Thank You

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