This document discusses object-oriented programming (OOP) concepts like classes, objects, encapsulation, inheritance, and polymorphism. It explains that OOP improves code reusability, modularity, and maintenance by encapsulating data and methods together as objects. Some benefits of OOP include improved communication, seamless design to implementation, and code reuse through inheritance. Potential drawbacks include increased complexity, overhead from derived classes implementing base class functionality, and a high learning curve.

1. BY
N.RUBA
ASST.PROF/DEPT. OF CA,
BON SECOURS COLLEGE FOR WOMEN,
THANJAVUR.

2.  JAVA - A general purpose, high-
level, object-oriented, cross-
platform programming language developed
by James Gosling at Sun Microsystems in
1995.
 In structured programming, a complex
program is broken into sets of smaller,
understandable tasks; but it is very hard to
maintain.

3.  Introduction to oop
◦ A procedure is defined as a collection of
instruction executed in sequential order.
 Oops concept was introduced by Xerox
Corporation in early 1970s.
 The first object oriented language was
Smalltalk.
 Oops languages: C++,Java and Eiffel.

4.  Objects and Classes are building blocks of
OOP.
 Object is a Programming entity in OOP.
◦ It has data components representing the present
state of the object as well as functions also called
methods.
 Object contains
◦ Attributes- data associated with the object
◦ Methods-functions and code which operate on the
data

5.  Class is a model or pattern from which an
object is created.
 Class is a special module that defines an
object.
◦ The process of creating an object from a class is
called instantiation.
◦ Every object is an instance of a particular class

6.  There are 3 main characteristics
Encapsulation
•Abstraction via
encapsulation
•Data hiding
Inheritance
•Single
•multiple
Polymorphism
•Operator overloading
•Function overloading

7. Encapsulation-The concept of sealing data and methods
that operate on the data into an object(a single unit) .
 Abstraction via encapsulation
 data hiding
 Abstraction via encapsulation
 Software object is an abstrat entity in that we view it
from outside. Without concerning oueselves with
detail of how it work on the inside.
 E.g Car and its gear.
 Dividing a program into modules is called
modularity. Not having to know the internal
implementation of a module is called abstraction

8.  Data hiding
◦ Encapsulation provide the hiding of data
information.
◦ It prevent user from seeing the internal working of
an object.
◦ This is used to protect data, that should not be
manipulated by the user.
◦ Every class can hide some of the part, every
element (field or method) of one class can have one
of the three level of visibility.
◦ They are
 Public
 Private and
 protected

9.  Public elements are completely visible from
outside the class. They form the interface
with the outside world
 Private elements are visible only to methods
of the class itself.
 Protected elements are something between
public and private.
◦ (act as private elements, but they are completely
visible to inherited child classes)

10.  Benefits of encapsulation
◦ Improves program reliability
◦ Reduces maintenance
◦ Lends usability
◦ Facilitates information hiding
◦ Improves modularity
◦ Makes coding easier

11. BASE CLASS
CHILD CLASS
BASE CLASS
CHILD CLASS

12.  Advantages of using inheritance :
◦ Increased productivity
◦ Reduced maintenance
◦ Standardization
 The major drawback of inheritance is added overhead.
 An user must know changes in the methods of base class before using the
derived classobjects.
 Though the derived class objects may not require all the functionalities of
a base class,the derived class implements all the methods of base class.
This increases the amount ofmemory required for execution of the
program.
 Since common functionalities exist in the base class, there is an execution
overhead forderived class due to the implementation of base class
methods when compared to havingthe functionalities in a single class
itself. In the case of a chain of inheritances, the executionOverhead may
increase further.

13.  Allows an entity to take a variety of
representations
◦ Operator overloading
 Is the ability to use an operator on different argument
types e.g operator ‘+’ is used to add either integers or
floating point numbers.(for adding two nos and
concatenation of two strings)
 Java does not support user-defined operator
overloading.

14.  Function overloading
◦ -is the ability to access different implementations
of functions using the same name.
◦ E.g
 printdate(String Str) {……}
 //ans: August 3,2020
 Printdate(int dd,int mm, int yyyy) {…..}
 //ans:3,8,2020

15.  Two types of function overloading
◦ Early binding
 Allows us to have two functions in the same class that
have the same name with different parameters and
different datatypes passed to it.
 E.g add(int a, int b)
 add(int a, int b, float c)
 Early binding takes place during compile time.
◦ Late binding

16.  Late binding
◦ Allows us to have functions with same name in base
and derived classes. But the derived class function
will override the base class function.
 Base class functions draw()
 Derived function fill()

17.  METHOD OVERRIDING
SHAPE
DRAW( )
DRAW( ) DRAW( ) DRAW( )

18.  In classical procedural (or structural) programming, there are techniques to
write a code that handles some general task
 The most important techniques of that kind are functions (proceduresor sub-
routines). The large program is partitioned into functions that each perform a
specifictask.
 The main program calls these functions, which in turn may call other
functions. The majorconcern of this programming is with respect to the data.
Data are passed around from one non-member function to another and are
available everywhere throughout the large program.
 This allows the user to access the data directly, alter it from several points in
the program and inadvertently introduce mistakes. If one
programmerchanges the representation of the data in the computer's
memory by rearranging fields withina structure (record), other functions in
the program may need to be rewritten and must then beretested to account
for this change. That means the data are not well protected in
procedureoriented programming. Though local variables in a function can be
accessed within the function,they are not useful if they must be accessed by
different functions.

19.  In contrast, OOP safely encapsulates
collections of functions (called methods)
with the data they manipulate.
 The data can only be manipulated by its
own functions.
 This feature protects the data from rest of
the program.Though the concepts of object
oriented programming are different from
procedural oriented programming,
structured programming constructs are still
used in OOP especially in the codingof
methods.

20.  Code reusability
 Code modularity
 Easier maintenance
 Design stability
 Improved communication between developers
and users
 Seamless transition from design to
implementation

21.  Execution overhead-derived classes can be
very complex because of inheritance and
polymorphism
◦ Once a derived class is initiated all the data and
functions from the base classes are carried along
with it.some of these , or even most of it may not
be used
 Abstraction may lead to performance
degradation

22.  High learning curve
◦ OOP is different from traditional programming.
◦ We must develop strong base classes and
understand the functionality of class libraries
before take advantages from it.
 Difficulty in establishing base classes
◦ Good foundation must be created before derive
other classes.