Florida Community College at Jacksonville

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Florida Community College at Jacksonville
Object-Oriented Concepts Overview
COP 2551 Object-Oriented Programming Spring,20
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Florida Community College at Jacksonville

• Objective
• Overview of Object Orientation
• Object Attributes and Operations
• Difference between an object and a class
• 3 basic Object-oriented principles
  (Encapsulation, Inheritance and Polymorphism)
• Reference Thinking in Java (Bruce Eckel)
• Free download _at_http//www.BruceEckel.com

COP 2551 Object-Oriented Programming OO
Concepts Overview
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• Overview of Object Orientation
• Object orientation is a technique for system
  modeling, Object oriented analysis and design, or
  OOAD, attempts to describe a system as it exists
  in real life.
• The system is modeled as a number of related
  objects that interact. Any system needs objects
  to do work. It asks its objects to do its work,
  just as you might ask objects in an online store
  to deliver goods to you and charge the cost to
  your credit card.
• All objects have attributes (characteristics),
  this is sometimes referred to as state.
• They also have operations (or methods), this is
  sometimes referred to as behavior.

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COP 2551 Object-Oriented Programming OO
Concepts Overview
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• Examples of Objects
• Use an online store (such as amazon.com) as an
  example, the following things may consider as
  Objects
• Book
• Customer
• Order

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Concepts Overview
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• Object Attributes and Operations
• Attributes know something (Attributes are often
  data, like order ID and customer ID for an Order
  object. Attributes can also be another object,
  such as the entire Customer object rather than
  just the customer ID.
• Operations do something with what the attributes
  know, (Operations can be actions that the object
  does, often affecting its attributes.)

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COP 2551 Object-Oriented Programming OO
Concepts Overview
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• Difference Between Object And Class
• A class is how you define an object. Classes are
  descriptive categories or templates. Book could
  be a class.
• Objects are unique instances of classes. This
  Java Certification book that costs 59.99 with
  item ID 62467-B is an object of the Book class.

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Concepts Overview
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• Difference Between Object And Class (continue)
• The attributes and operations defined by a class
  are for its objects, not for itself. There is no
  concrete realization of the class Book, but there
  are Book objects, i.e. a class is a logical
  construct, an object has physical reality.
• A class can be compared to a blueprint. Imagine
  you are in charge of building a housing
  development, with one housing blueprint. Each
  house in a development is shaped the same way,
  but some have brick or aluminum siding, some have
  custom paint colors inside and some are just
  white, and so on.

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Concepts Overview
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• Object-oriented Principle Encapsulation
• Encapsulation is the mechanism that binds
  together the code and the data it manipulates,
  and keeps both safe from outside interference and
  misuse.

A Class
Public variables and methods
Private variables and methods
Public variables is not recommended
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Concepts Overview
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• Object-oriented Principle -
  Inheritance
• Inheritance is the process by which one object
  acquires the properties of another object. By use
  of inheritance, an object need only define all of
  its characteristics that make it unique within
  its class, it can inherit its general attributes
  from its parent.

Account
Checking
Mortgage
Loan
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Concepts Overview
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• Object-oriented Principle Polymorphism
• Polymorphism(from Greek, meaningmany forms) is
  a feature that allows one interface to be used
  for a general class of actions, i.e. one
  interface, multiple methods.
• Example Account.calculateInterest()

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COP 2551 Object-Oriented Programming OO
Concepts Overview