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Introduction
DKT216
Lecturer
• Dr Amiza Amir
• [email protected]
• 0134288966 (8.00 am to 6.00 pm)
Course Outcome
• CO1: Ability to explain object-oriented
programming concept.
• CO2: Ability to apply object-oriented programming
concept in software development.
• CO3: Ability to initiate application development
using OOP-based Graphical User Interface (GUI)
library
Word of Wisdom
I hear and I forget. I see and I remember. I do and I
understand
-Confucius
Recommended References
•
Programming -- Principles and Practice Using C++ by Bjarne
Stroustrup Addison-Wesley ISBN 978-0321-992789. May 2014.
C++ Inventor
Bjarne Stroustrup
Recommended References
•
Design Patterns : Elements of Reusable Object-Oriented Software
by Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides
(Gang of Four)
Recommended References
Head First Design Patterns by Eric Freeman, Bert Bates, Kathy Sierra
and Elisabeth Robson
Procedural Programming
•
Traditional procedural-oriented programming
languages (such as C, Fortran, Cobol and Pascal)
suffer some notable drawbacks in creating reusable
software components:
•
The procedural-oriented programs are made up of
functions. Functions are less reusable. It is very
difficult to copy a function from one program and
reuse in another program because the function is
likely to reference the global variables and other
functions. In other words, functions are not wellencapsulated as a self-contained reusable unit.
•
The procedural languages are not suitable of high-level
abstraction for solving real life problems. For example,
C programs uses constructs such as if-else, for-loop,
array, method, pointer, which are low-level and hard
to abstract real problems.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
Procedural Programming :
Top Down Design
• Start with a problem (procedure).
• Systematically break the problem down into sub
problems (sub procedures)---called functional
decomposition. This process continues until a subproblem is straightforward enough to be solved by the
corresponding sub-procedure.
• The difficulties with this type of programming, is that
software maintenance can be difficult and time
consuming ---when changes are made to the main
procedure (top), those changes can cascade to the sub
procedures of main, and the sub-sub procedures and so
on.
The Birth of Object-oriented
Programming (OOP)
•
In the early 1970s, the US Department of Defense (DoD) commissioned a task force
to investigate why its IT budget always went out of control; but without much to
show for. The findings are:

80% of the budget went to the software (with the remaining 20% to the hardware).

More than 80% of the software budget went to maintenance (only the remaining
20% for new software development).

Hardware components could be applied to various products, and their integrity
normally did not affect other products. (Hardware can share and reuse! Hardware
faults are isolated!)

Software procedures were often non-sharable and not reusable. Software faults could
affect other programs running in computers.
•
The task force proposed to make software behave like hardware OBJECT.
Subsequently, DoD replaces over 450 computer languages, which were then used to
build DoD systems, with an object-oriented language called Ada.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
Object-oriented Programming
(OOP)
• Solve the difficulties with procedural programming.
• In object-oriented programming (OOP), the main
modules in a program are classes, rather than
procedures.
• Classes and objects in OOP model real world
objects.
OOP Concepts
• The basic unit of OOP is a
class, which encapsulates both
the static properties and
dynamic operations within a
"box", and specifies the public
interface for using these
boxes. Since classes are wellencapsulated, it is easier to
reuse these classes. In other
words, OOP combines the
data structures and
algorithms of a software
entity inside the same box.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
OOP Concepts
• OOP languages permit higher level of abstraction for solving
real-life problems. The traditional procedural language (such
as C and Pascal) forces you to think in terms of the
structure of the computer (e.g. memory bits and bytes,
array, decision, loop) rather than thinking in terms of the
problem you are trying to solve.
•
The OOP languages (such as Java, C++ and C#) let you
think in the problem space, and use software objects to
represent and abstract entities of the problem space to solve
the problem.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
OOP Concepts
• In object-oriented programming, a class is a template
for creating objects. The template is a particular set
of attributes and behaviors.
• An object is an instance of a class. Objects
implement class attributes as data and class
behaviors as functions.
• In other words, a class is a collection of objects that
have common attributes and behaviors. A class is a
combination of attributes (data) and behavior
(methods).
OOP Concept: Class
• Example
A class Human represents all humans in the world.
Humans have attributes, such as height, weight, and
hair color. They also have behavior, such as walking,
talking, eating. All of the attributes and behavior of a
human are encapsulated (contained) within the class
human.
OOP Concept: Object
• An object is an instance of a class. Objects are units
of abstraction.
• An object can communicate with other objects using
messages.
• Objects then perform the actions that are required to
get a response from the system.
OOP Concept: Object
• Examples
Two examples object from the class Human are :
1) Abu
Height: 6’; Weight : 90 kg; Hair colour : Black
2) Kerri
Height: 5’ 5”; Weight : 62 kg; Hair colour : Brown
Both Abu and Kerri can walk, talk, and eat. However, the
way they do these actions may be different from each other.
Procedural Programming and
OOP
The procedural-oriented languages focus on
procedures, with function as the basic unit. You need
to first figure out all the functions and then think about
how to represent data.
The object-oriented languages focus on components
that the user perceives, with objects as the basic unit.
You figure out all the objects by putting all the data
and operations that describe the user's interaction with
the data.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
OOP Benefits
• Ease in software design as you could think in the problem
space rather than the machine's bits and bytes. You are
dealing with high-level concepts and abstractions. Ease in
design leads to more productive software development.
• Ease in software maintenance: object-oriented software are
easier to understand, therefore easier to test, debug, and
maintain.
• Reusable software: you don't need to keep re-inventing the
wheels and re-write the same functions for different
situations. The fastest and safest way of developing a new
application is to reuse existing codes - fully tested and
proven codes.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
Example : A computer soccer
games
Using OOP languages, you can easily model the program accordingly to the
"real things" appear in the soccer games.
Player: attributes include name, number, location in the field, and etc;
operations include run, jump, kick-the-ball, and etc.
Ball:
Reference:
Field:
Audience:
Weather:
Some of these classes (such as Ball and Audience) can be reused in another
application, e.g., computer basketball game, with little or no modification.
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html
Example : A computer soccer
game
http://www.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html