object oriented rogramming with question and answer full

UNIT STRUCTURE

Basics overview of programming paradigms Features of OOPS Classes Encapsulation Polymorphism Inheritance

LEARNING OBJECTIVES

After going through this unit you should be able to

find the importance of OO approach

define the basic concepts of OO approach

differentiate between object and procedure-oriented approaches

know about various OO languages

describe the applications of OOP and

Understand the benefits of OO approach

1 Object oriented programming

Javas origins go back to 1991 when Sun Microsystems began looking for ways to create

platform-independent code to support consumer electronic products After some initial

efforts with C++ the Sun project team abandoned it and created its own language initially

called Oak later renamed Java Oak first was used to create software for a personal hand-

held remote control device but when the project team lost a bid to develop a television set-

top box for Time-Warner attention switched to the Web The Sun project team then built a

Web browser originally called WebRunner and then renamed HotJava in the Java

programming language The rest as they say is history Sun formally announced Java and

HotJava at the SunWorld 95 conference in San Francisco on May 23 1995

UNIT 1 OBJECT ORIENTED ROGRAMMING

Object-oriented programming (OOP) is a programming language model organized around

objects rather than actions and data rather than logic Historically a program has been viewed

as a logical procedure that takes input data processes it and produces output data The

programming challenge was seen as how to write the logic not how to define the data Object-

oriented programming takes the view that what we really care about are the objects we want to

manipulate rather than the logic required to manipulate them Examples of objects range from

human beings (described by name address and so forth) to buildings and floors (whose

properties can be described and managed) down to the little widgets on a computer desktop (such

as buttons and scroll bars)

Real world objects

The first step in OOP is to identify all the objects the programmer wants to manipulate and how

they relate to each other an exercise often known as data modeling Once an object has been

identified it is generalized as a class of objects (think of Platos concept of the ideal chair that

stands for all chairs) which defines the kind of data it contains and any logic sequences that can

manipulate it Each distinct logic sequence is known as a method Objects communicate with

well-defined interfaces called messages

The concepts and rules used in object-oriented programming provide these important

benefits

a) The concept of a data class makes it possible to define subclasses of data objects that

share some or all of the main class characteristics Called inheritance this property of

OOP forces a more thorough data analysis reduces development time and ensures more

accurate coding

b) Since a class defines only the data it needs to be concerned with when an instance of that

class (an object) is run the code will not be able to accidentally access other program

data This characteristic of data hiding provides greater system security and avoids

unintended data corruption

c) The definition of a class is reuseable not only by the program for which it is initially

created but also by other object-oriented programs (and for this reason can be more

easily distributed for use in networks)

d) The concept of data classes allows a programmer to create any new data type that is not

already defined in the language itself

EVOLUTION OF OO METHODOLOGY

Simula was the first object-oriented programming language Java Python C++ Visual

Basic NET and Ruby are the most popular OOP languages today The Java programming

language is designed especially for use in distributed applications on corporate networks and the

Internet Ruby is used in many Web applications Curl Smalltalk Delphi and Eiffel are also

examples of object-oriented programming languages

Java is an object-oriented programming language based on C++ that allows small programs -- or

applets -- to be embedded within an HTML document When the user clicks on the appropriate

part of the HTML page to retrieve it from a Web server the applet is downloaded into the client

workstation environment where it begins executing [Editors note Since this text was written

the definition of Java has expanded beyond Web-based applets Sun expects the language to be

used for all sorts of applications and promises a Java operating system Java microprocessors

and more -- and now refers to Java as a platform

The relationship among Java programs (or applets) the Java-enabled browser and the Web is

illustrated in Figure Users access a Web page and pull it down to their client In this case

though the Web page contains an additional HTML tag called APP which refers to a Java

applet and that applet can be located anywhere on the Web If the users Web browser is Java-

enabled (for example Suns HotJava browser or Netscapes Navigator 20) then the applet is

pulled down into the users client computer and executed within the browser environment

Java is often described as a cross-platform programming language its also common to refer to Java

programs as architecture-neutral byte codes It has to be this way of course because the Web server

that delivers the Java applet to the Web client doesnt know what kind of hardwaresoftware environment

its running on And the developer who creates the Java applet doesnt want to worry about whether it will

work correctly on OS2 Windows Unix and MacOS

1) The Java compiler javac which translates human-readable Java source code to architecture-neutral bytecodes

2) The Java interpreter which executes Java programs on the users PC or workstation

3) The C header and source file generator javah and java_g These are used to generate header files for C as well as source files for making methods (roughly equivalent to procedures or subroutines in other languages) within Java

4) The Java disassembler javap which prints out information about a class file (a file containing a Java applet)

5) The document generator javadoc which is capable of generating an HTML file from a Java source-code file

6) The profiling tool javaprof which formats the performance data created if the programmer uses the -prof option in the Java interpreter to obtain statistics on run time and performance

Security and robust behavior

Security and robustness are obviously important in the distributed environment represented by

the Internet if you download a Java applet from a Web server for example you really dont

want it to run amok on your computer and delete all the files on your hard disk This is not as far-

fetched as it might sound because the incorporation of Java applets into Web pages means that

you may be invoking computer programs written by people anywhere in the world located

anywhere on the Web Indeed once you begin using a Java-enabled browser youre

automatically at risk since you dont know at the moment you decide to retrieve a Web page (say

by clicking on a hyperlink within an existing page being displayed on your computer) whether it

will contain embedded Java applets

Sun has addressed this concern by imposing severe constraints on the Java programming

language as well as extensive run-time checking in the interpreter located inside the Java-

enabled browser The Java language for example forbids the use of address pointers and pointer

arithmetic found in C and C++ this eliminates a large class of innocent errors that might

otherwise plague the user of Java applets In addition the following steps have been taken to

increase the level of security and robust behavior

1) The Java run-time interpreter verifies that bytecodes (the compiled architecture-neutral

form of Java applet that gets downloaded from the Web server into the users machine)

dont violate any language constructs -- which could happen if an altered Java compiler

was used by a hacker The verification logic checks to make sure that the Java applet

doesnt access restricted memory forge memory pointers or access objects in a manner

inconsistent with its definition It also ensures that method (subroutine) calls include the

correct number of arguments of the right type and that there are no stack overflows

2) During loading of the Java applet the run-time interpreter verifies class names (a class

is an entire Java applet) and access restrictions

3) If a Java applet attempts to access a file for which it has no permission a dialog box will

pop up to allow the user to continue or stop the execution of the applet

4) Future releases of Java are planned to have facilities for using public key encryption to

verify the source and origin of the Java source code and its integrity after traveling

through the network to reach the users machine

5) At run time information about the origin of the Java applet can be used to decide what

the applet is allowed to do For example a security mechanism can be used to determine

whether the compiled Java byte codes originated from within an organizations security

firewall or not This makes it possible to set a security policy that restricts the use and

execution of Java code that an organization doesnt know or trust

This last point is crucial for there are likely to be a number of attempts -- both innocent and

malicious -- to circumvent the security mechanisms that Sun has built into the language In its

white paper on the Java language Sun expresses the following optimistic statement about Java

security Java is designed to operate in distributed environments which means that security is of

paramount importance With security features designed into the language and run-time system

Java lets you construct applications that cant be invaded from outside In the networked

environment applications written in Java are secure from intrusion by unauthorized code

attempting to get behind the scenes and create viruses or invade file systems For the security-

conscious organizations though the firewall protection mentioned above will be crucial -- at

least in the short term

Basics overview of programming paradigms

The term paradigm describes a set of techniques methods theories and standards that together represent

a way of thinking for problem solving According to [Wegner 1988] paradigms are ldquopatterns of

thought for problem solvingrdquo Language paradigms were associated with classes of languages First the

paradigms are defined Thereafter programming languages according to the different paradigms are

classified The language paradigms are divided into two parts imperative and declarative paradigms as

shown in the Figure 1 Imperative languages can be further classified into procedural and object

oriented approach Declarative languages can be classified into functional languages and logical

languages In Figure1 the examples of languages in each category are also given

Language Paradigms

Computer programmers have evolved from the early days of the bit processing first generation

languages into sophisticated logical designers of complex software applications A programming

paradigm is the logical approach used in software engineering that describes how a programming

language is implemented Programming paradigms are unique to each language within the

computer programming domain and many programming languages utilize multiple paradigms

The term paradigm is best described as a pattern or model Therefore a programming

paradigm can be defined as a pattern or model used within a software programming language to

create software applications

Programming languages are extremely logical and follow standard rules of mathematics Each

language has a unique method for applying these rules especially around the areas of functions

variables methods and objects There are many programming paradigms examples include

object oriented procedural and structured programming Each paradigm has unique

requirements on the usage and abstractions of processes within the programming language

Features of OOPS

Object oriented methods are favored because many experts agree that Object Oriented techniques

are more disciplined than conventional structured techniques (Martin and Odell 1992)

The main components of Object Oriented technology are lsquoobjects and classesrsquo lsquodata

abstraction and encapsulationrsquo lsquoinheritancersquo and lsquopolymorphismrsquo It is very important for

you to understand these concepts Further in this unit you can find the details of these concepts

a) Object oriented programming (OOP) is a programming model where Programs are organized around object and data rather than action and logic OOP allow decomposition of a problem into a number of entities called Object and then builds data and function around these objects

b) The Program is divided into number of small units called Object The data and function are build around these objects

c) The data of the objects can be accessed only by the functions associated with that objectd) The functions of one object can access the functions of other object

OOP has the following important features

ClassA class is the core of any modern Object Oriented Programming languageIn OOP languages it is must to create a class for representing data Class is a blueprint of an object that contains variables for storing data and functions to performing operations on these data Class will not occupy any memory space and hence it is only logical representation of data

To create a class you simply use the keyword class followed by the class nameclass Employee

Object

Objects are the basic run-time entities in an object oriented systemThey may represent a

persona place or any item that the program has to handle

Object is a Software bundle of related variable and methods

ldquoObject is an instance of a classrdquo

Class will not occupy any memory space Hence to work with the data represented by the class you must create a variable for the class which is called as an object When an object is created by using the keyword new then memory will be allocated for the class in heap memory area which is called as an instance and its starting address will be stored in the object in stack memory area

When an object is created without the keyword new then memory will not be allocated in heap Ie instance will not be created and object in the stack contains the value nullWhen an object contains null then it is not possible to access the members of the class using that object

class Employee

Syntax to create an object of class Employee-

Employee objEmp = new Employee()

Similarly the following can be treated as objects in different programming problems

Employees in a payroll system Customers and accounts in a banking system Salesman products customers in a sales tracking system Data structures like linked lists stacks etc Hardware devices like magnetic tape drive keyboard printer etc GUI elements like windows menus events etc in any window-based application

All the programming languages supporting object oriented Programming will be supporting these three main concepts

1 Encapsulation2 Inheritance3 Polymorphism

AbstractionAbstraction is To represent the essential feature without representing the back ground details

Abstraction lets you focus on what the object does instead of how it does it

Abstraction provides you a generalized view of your classes or object by providing relevant information

Abstraction is the process of hiding the working style of an object and showing the information of an object in understandable manner

Real world Example of Abstraction - Suppose you have an object Mobile Phone

Suppose you have 3 mobile phones as following-

Nokia 1400 (Features- Calling SMS)Nokia 2700 (Features- Calling SMS FM Radio MP3 Camera)Black Berry (Features-Calling SMS FM Radio MP3 Camera Video Recording Reading E-mails)

Abstract information (Necessary and Common Information) for the object Mobile Phone is make a call to any number and can send SMS

so that for mobile phone object you will have abstract class like following-

abstract class MobilePhone public void Calling() public void SendSMS()

public class Nokia1400 MobilePhone

public class Nokia2700 MobilePhone public void FMRadio() public void MP3() public void Camera()

public class BlackBerry MobilePhone public void FMRadio() public void MP3() public void Camera() public void Recording() public void ReadAndSendEmails()

Abstraction means putting all the variables and methods in a class which are necessaryFor example - Abstract class and abstract methodAbstraction is the common thingexample If somebody in your collage tell you to fill application form you will fill your details like name address data of birth which semester percentage you have got etcIf some doctor gives you an application to fill the details you will fill the details like name address date of birth blood group height and weight

See in the above example what is the common thingAge name address so you can create the class which consist of common thing that is called abstract class That class is not complete and it can inherit by other class

Encapsulation Wrapping up data member and method together into a single unit (ie Class) is called Encapsulation

Encapsulation is like enclosing in a capsule That is enclosing the related operations and data related to an object into that object

Encapsulation is like your bag in which you can keep your pen book etc It means this is the property of encapsulating members and functions

class Bag book pen ReadBook()

Encapsulation means hiding the internal details of an object ie how an object does something

Encapsulation prevents clients from seeing its inside view where the behaviour of the abstraction is implemented

Encapsulation is a technique used to protect the information in an object from the other object

Hide the data for security such as making the variables as private and expose the property to access the private data which would be publicSo when you access the property you can validate the data and set it

Example

class Demo private int _mark

public int Mark get return _mark set if (_mark gt 0) _mark = value else _mark = 0

Real world Example of Encapsulation-Lets take example of Mobile Phone and Mobile Phone ManufacturerSuppose you are a Mobile Phone Manufacturer and you designed and developed a Mobile Phone design(class) now by using machinery you are manufacturing a Mobile Phone(object) for selling when you sell your Mobile Phone the user only learn how to use the Mobile Phone but not that how this Mobile Phone works

This means that you are creating the class with function and by making object (capsule) of it you are making availability of the functionality of you class by that object and without the interference in the original class

Example-2 TV operation It is encapsulated with cover and we can operate with remote and no need to open TV and change the channelHere everything is in private except remote so that anyone can access not to operate and change the things in TV

Inheritance Inheritance is the process by which objects of one class acquire the properties of

objects of another class in the hierarchy For example the scooter is a type of the class two-

wheelers which is again a type of (or kind of) the class motor vehicles As shown in the Figure 5

the principle behind it is that the derived class shares common characteristics with the class from

which it is derivedNew classes can be built from the existing classes It means that we can add

additional features to an existing class without modifying it The new class is referred as derived

class or sub class and the original class is known as base class or super class Therefore the

concept of inheritance provides the idea of reusability This inheritance mechanism allows the

programmer to reuse a class that is made almost but not exactly similar to the required one by

adding a few more features to it As shown in Figure 5 three classes have been derived from one

base class Feature A and Feature B of the base class are inherited in all the three derived classes

Also each derived class has added its own features according to the requirement

Therefore new classes use the concept of reusability and extend their functionality

When a class acquire the property of another class is known as inheritanceInheritance is process of object reusability

For example A Child acquires property of Parents

public class ParentClass public ParentClass() ConsoleWriteLine(Parent Constructor)

public void print() ConsoleWriteLine(Im a Parent Class)

public class ChildClass ParentClass public ChildClass() ConsoleWriteLine(Child Constructor)

public static void Main() ChildClass child = new ChildClass()

childprint()

Output Parent Constructor Child Constructor Im a Parent Class

Polymorphism

Polymorphism means one name many formsOne function behaves different formsIn other words Many forms of a single object is called Polymorphism

Real World Example of PolymorphismExample-1 A Teacher behaves to studentA Teacher behaves to hisher seniorsHere teacher is an object but attitude is different in different situationExample-2

Person behaves SON in house at the same time that person behaves EMPLOYEE in officeExample-3 Your mobile phone one name but many forms

As phone As camera As mp3 player As radio

Difference between Abstraction and Encapsulation-

Abstraction Encapsulation

1 Abstraction solves the problem in the

design level

1 Encapsulation solves the problem in the

implementation level

2 Abstraction is used for hiding the

unwanted data and giving relevant data

2 Encapsulation means hiding the code and

data into a single unit to protect the data from

outside world

3 Abstraction lets you focus on what the

object does instead of how it does it

3 Encapsulation means hiding the internal

details or mechanics of how an object does

something

4 Abstraction- Outer layout used in terms

of design

For Example-

Outer Look of a Mobile Phone like it has a

display screen and keypad buttons to dial a

number

4 Encapsulation- Inner layout used in

terms of implementation

For Example- Inner Implementation detail of

a Mobile Phone how keypad button and

Display Screen are connect with each other

using circuits

The easier way to understand Abstraction and encapsulation is as follows-

Real World Example-

Take an example of Mobile Phone-

You have a Mobile Phone you can dial a number using keypad buttons Even you dont know

how these are working internally This is called Abstraction You have the only information that

is needed to dial a number But not its internal working of mobile

But how the Mobile Phone internally working how keypad buttons are connected with internal

circuit is called Encapsulation

BENEFITS OF OOPS

OOP offers several benefits to both the program developer and the user The new technology provides

greater programmer productivity better quality of software and lesser maintenance cost The major

benefits are

o Ease in division of job Since it is possible to map objects of the problem domain to

those objects in the program the work can be easily partitioned based on objects

o Reduce complexity Software complexity can be easily managed

o Provide extensibility Object oriented systems can be easily upgraded from small to

large system

o Eliminate redundancy Through inheritance we can eliminate redundant code and

extend the use of existing classes

o Saves development time and increases productivity Instead of writing code from

scratch solutions can be built by using standard working modules

o Allows building secure programs Data hiding principle helps programmer to build

secure programs that cannot be accessed by code in other parts of the program

o Allows designing simpler interfaces Message passing techniques between objects

allows making simpler interface descriptions with external systems

Object Oriented Approach

The salient features of Object oriented programming are

More emphasis is on data rather than procedure

Programs are modularized into entities called objects

Data structures methods characterize the objects of the problem

Since the data is not global there is no question of any operations other than those

defined within the object accessing the data Therefore there is no scope of accidental

modification of data

It is easier to maintain programs The manner in which an object implements its

operations is internal to it Therefore any change within the object would not affect

external objects Therefore systems built using objects are resilient to change

Object reusability which can save many human hours of effort is possible An

application developer can use objects like lsquoarrayrsquo lsquolistrsquo lsquowindowsrsquo lsquomenusrsquo lsquoeventrsquo and

many other components which were developed by other programmers in her program

and thus reduce program development time

It employs bottom-up approach in program design

SUMMARY

OOP is a new way of organizing and developing programs It eliminates many pitfalls of the

conventional programming approach OOP programs are organized around objects which

contain data and functions that operate on that data A class is a template for a number of objects

The object is an instance of a class The major features of OOP are data abstraction data

encapsulation inheritance and polymorphism

Encapsulation is accomplished by using Class - Keeping data and methods that accesses

that data into a single unit

Abstraction is accomplished by using Interface - Just giving the abstract information

about what it can do without specifying the back ground details

InformationData hiding is accomplished by using Modifiers - By keeping the instance

variables private or protected

This new methodology increases programmer productivity delivers better quality of software

and lessens maintenance cost Languages that support several OOP concepts include C++

Smalltalk Object Pascal and Java

1048590 Check Your Progress 11) What do you understand by structured programminghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip2) What is the basic idea of Object Oriented approachhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip3) Differentiate between Data abstraction and data hidinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip4) Differentiate between Inheritance and polymorphism

helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip

1048590 Check Your Progress 2

1) State True or False

a) In the procedure-oriented approach all data are shared by all functions

b) One of the major characteristics of OOP is the division of programs into objects that represent real-

world entities

c) Object Oriented programming language permit reusability of the existing code

d) Data is given a second-class status in procedural programming approach

e) OOP languages permit functional as well as data abstraction

2) Does procedure oriented language support the concept of class

helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip3) Give the reason of accessing data of a class through its functions onlyhelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip



a) Protecting data from access by unauthorized functions is called data hiding

b) Wrapping up of data of different types and functions into a unit is known as encapsulation

c) Polymorphism can be used in implementing inheritance

d) A Class permits us to build user-defined data types

e) Object Oriented approach cannot be used to create databases

2) Explain the advantage of dynamic bindinghelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip

3) Differentiate between object based and object oriented programming languageshelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellip

1048590 SOLUTIONSANSWERS

Check Your Progress 1

1) In structured programming a program is divided into functions or modules and each module has a

clearly defined purpose and a defined interface to the other functions in the program Dividing a program

into functions and modules is one of the major characteristics of structured programming Here we are

least bothered about the data of the problem provided Our main objective is to achieve control of the

execution of program correctly

2) In Object Oriented programming (OOP) the program is organized around the data being operated

upon rather than the operations performed The basic idea behind OOP is to combine both data and its

functions that operate on the data into a single unit called object

3) In data abstraction data structures are used without having to be concerned about the exact details of

implementation This insulation of the data from direct access by the other elements of the program is

known as data hiding It is achieved through classes in OOPs

4) Inheritance is the process by which objects of one class acquire the properties of objects of another

class in the hierarchy By using inheritance new classes can be built from the existing old classes It

means that we can add additional features to an existing class without modifying it This inheritance

mechanism allows the programmer to reuse a class that is almost but not exactly similar to the required

one by adding a few more features to it Polymorphism means the ability to take more than one form with

the same name

Using polymorphism we can have more than one function with the same name but with different

functionalities

Check Your Progress 21) False b) True c) True d) True e) True

2) Yes procedural languages also support the concept of class for example type (data type of the

language) is a class and is supported by procedural languagesYou know C language support several data

types But procedural languages donrsquot support the user-defined class that has data and functions together

3) Accessing data of a class through its functions is in basic philosophy of object orientation If data is not

having restrictive access and open to all the principle of data hiding is violated and emphasis on data get

reduced


1) True b) True c) True d) True e) False

2) It gives option of run-time selection of methods on the basis of current input during execution of

program Dynamic binding allows new objects and code to be interfaced with or added to a system

without affecting existing code

3) Object based languages support the notion of objects Object oriented languages support the concept of class and permit inheritance between classes

1048590 Multiple choiceobjective type questions

1) Which language is not a true object-oriented programming language

a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI

a) uses buttons menus and icons

b) should be easy for a user to manipulate

c) stands for Graphic Use Interaction

d) Both a and b

e) All of the above

Answer d 3) An object is composed of

a) properties

b) methods

c) events

d) Both a and b

e) All of the above

Answer e 4) Which statement about objects is true

a) One object is used to create one class

b) One class is used to create one object

c) One object can create many classes

d) One class can create many objects

e) There is no relationship between objects and classes

Answer d5) Which is a numeric data type

a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise

Questions and Answers

1 What is the most important feature of Java

Ans Java is a platform independent language

2 What do you mean by platform independence

Ans Platform independence means that we can write and compile the java code in one platform (eg Windows) and can execute the class in any other supported platform eg (LinuxSolarisetc)

3 What is a JVM

Ans JVM is Java Virtual Machine which is a run time environment for the compiled java class files

4 Are JVMs platform independent

Ans JVMs are not platform independent JVMs are platform specific run time implementation provided by the vendor

5 What is the difference between a JDK and a JVM

Ans JDK is Java Development Kit which is for development purpose and it includes execution environment also But JVM is purely a run time environment and hence you will not be able to compile your source files using a JVM

6 What is a pointer and does Java support pointers

Ans Pointer is a reference handle to a memory location Improper handling of pointers leads to memory leaks and reliability issues hence Java doesnt support the usage of pointers

Answer the following questions

(Questions for short notes)

1 Can a private method of a super class be declared within a subclass

2 Why Java does not support multiple inheritance

3 In Systemoutprintln () what is Systemout and printlnpls explain

4 What is meant by Abstract Interface

5 Why Java does not support pointers

6 What is the main difference between Java platform and other platforms

(Questions for short Answer)

1 What is the base class of all classes

2 Does Java support multiple inheritance

3 Is Java a pure object oriented language

4 Are arrays primitive data types

5 What is difference between Path and Classpath

6 What are local variables

Reference 1 Gosling James A brief history of the Green project[dead link] Javanet no date

[caQ11998] Retrieved April 29 2007

2 Gosling James A brief history of the Green project anonymous-insidernet no date [ca

Q11998] Retrieved September 4 2013

3 Gosling James Joy Bill Steele Guy L Jr Bracha Gilad (2005) The Java Language

Specification (3rd ed) Addison-Wesley ISBN 0-321-24678-0

4 Lindholm Tim Yelling Frank (1999) The Java Virtual Machine Specification (2nd ed)

Addison-Wesley ISBN 0-201-43294-3

5 The History of Java Technology Retrieved October 6 2012

6 Java 50 added several new language features C language Gosling James and

McGilton Henry (May 1996) The Java Language Environment

7 Gosling James Joy Bill Steele Guy and Bracha Gilad The Java Language

Specification 2nd Edition

8 The A-Z of Programming Languages Modula-3 Computerworldcomau Retrieved

2010-06-09

9 Tech Metrix Research (1999) History of Java Java Application Servers Report

ldquoByous Jon (ca 1998)Java technology The early years Sun Developer Network Sun

Microsystems

10 Object-oriented programming The History of Java Technology Sun Developer

Network ca 1995 Retrieved 2010-04-30

11 Java Community Process website Jcporg 2010-05-24 Retrieved 2010-06-09

12 Learn About Java Technology Oracle Retrieved 21 November 2011


Object-oriented programming (OOP) is a programming language model organized around

objects rather than actions and data rather than logic Historically a program has been viewed

as a logical procedure that takes input data processes it and produces output data The

programming challenge was seen as how to write the logic not how to define the data Object-

oriented programming takes the view that what we really care about are the objects we want to

manipulate rather than the logic required to manipulate them Examples of objects range from

human beings (described by name address and so forth) to buildings and floors (whose

properties can be described and managed) down to the little widgets on a computer desktop (such

as buttons and scroll bars)

Real world objects

The first step in OOP is to identify all the objects the programmer wants to manipulate and how

they relate to each other an exercise often known as data modeling Once an object has been

identified it is generalized as a class of objects (think of Platos concept of the ideal chair that

stands for all chairs) which defines the kind of data it contains and any logic sequences that can

manipulate it Each distinct logic sequence is known as a method Objects communicate with

well-defined interfaces called messages


benefits




accurate coding






























































































Language Paradigms














Features of OOPS












Object







class Employee






























Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems







benefits




accurate coding






























































































Language Paradigms














Features of OOPS












Object







class Employee






























Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems













































































Language Paradigms














Features of OOPS












Object







class Employee






























Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems









Object







class Employee






























Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems







class Employee






























Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems































Example

























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems




























childprint()


Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems







Polymorphism








design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems











design level







outside world





something


of design

For Example-



number






using circuits


Real World Example-







BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems






BENEFITS OF OOPS



benefits are





large system

























SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems





















SUMMARY





















world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems












world entities

































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems




































the same name


functionalities







reduced









a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems













a) VBNET

b) VB 6

c) C++

d) C

e) Java

Answer b 2) A GUI




d) Both a and b

e) All of the above


a) properties

b) methods

c) events

d) Both a and b

e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems






e) All of the above








a) Floating point

b) Integer

c) Boolean

d) Both a and b

e) All of the above

Answer d

1048590 Exercise






3 What is a JVM





































2010-06-09



Microsystems










































2010-06-09



Microsystems






object oriented rogramming with question and answer full

Education

java programming language

program data

java applet

input data

data modeling

kind of data

subclasses of data objects

output data