Upload
clyde-pierce
View
212
Download
0
Embed Size (px)
Citation preview
CIS1402 – Introduction to CIS
Tom Gustafson
*Object-Oriented Basics
*What Is an Object?
*An object is an entity that has attributes and methods.
*Ex: A light bulb is an object.
*The attributes of a light bulb could be:
* Florescent or Incandescent
*Watts
* Size
*The methods of a light bulb could be:
* Turn on
* Turn off
* Insert
*What Is an Object?
*With computers, there are many objects:
*Files
*User accounts
*Groups
*Hardware components
*Services
*What Is an Object?
*A User Account has attributes and methods
*Attributes (Properties or Data)
*Username
*Password
*Creation Date
*Methods (Actions or Operations)
*Disable Account
*Change Password
*Log off
*What Is an Object?
*Think of an attribute (property or data) of an object like a place holder to store information about the object. It’s like a variable. It’s like a field in a database record.
*Think of a method (action or operation) as something you do to the object. It’s like a function or procedure. It does something.
*What is a Class?
*A “Class” is at type or category of object.
*For example, “light bulb” is a class of object.
*All objects of class light bulb have the same attributes and methods.
*Attributes like watts, size, etc.
*Methods like turn on/off, insert, etc.
*But, two objects of the same class can have different values for their attributes. Ex: one may be 75 watt and another may be 100 watt.
*What is a Class?
*Here are some classes of real-life objects:
*Car
*Tree
*Person
*Book
*Every car has VIN, make, and model attributes and start and brake methods.
*An object is an instance of the class it is part of.
*What is a Class?
*On a Computer, there are many classes of objects. Here are three:
*Service
* Attributes: name, status, type
*Methods: start, stop, pause
*File
* Attributes: name, creation date, read-only
*Methods: delete, rename, open
*User Account
* Attributes: name, password, lockout status
*Methods: change password, log off, disable,
*Summary
*There are classes or categories of objects.
*An object is an instance of its class.
*Every class of object has the same:
*Methods – actions that can be performed on an object of that class
*Attributes – properties of every object of that class