1. SNSCT_CSE_PROGRAMMING PARADIGM_CS206
OOPS-FUNDAMENTALS
OOPS Review
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2. CSE_PROGRAMMING PARADIGM_CS206
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3. CSE_PROGRAMMING PARADIGM_CS206
RECAP
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4. CSE_PROGRAMMING PARADIGM_CS206
Recap
What is an Attribute?
What is an Operation?
What is an Object and what is a Class? What is the difference between them?
What is an Object?
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5. Object-Oriented Programming Revisited
Key OOP Concepts
Object, Class
Instantiation, Constructors
Encapsulation
Inheritance and Subclasses
Abstraction
Reuse
Polymorphism, Dynamic Binding
Object-Oriented Design and Modeling
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6. CSE_PROGRAMMING PARADIGM_CS206
OOPS-FUNDAMENTALS
Object
Definition: a thing that has identity, state, and behavior
identity: a distinguished instance of a class
state: collection of values for its variables
behavior: capability to execute methods
* variables and methods are defined in a class
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7. CSE_PROGRAMMING PARADIGM_CS206
Class
Definition: a collection of data (fields/ variables) and methods that operate on that data
define the contents/capabilities of the instances (objects) of the class
a class can be viewed as a factory for objects
a class defines a recipe for its objects
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8. CSE_PROGRAMMING PARADIGM_CS206
Instantiation
Object creation
Memory is allocated for the object’s fields as defined in the class
Initialization is specified through a constructor
a special method invoked when objects are created
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9. CSE_PROGRAMMING PARADIGM_CS206
Encapsulation
A key OO concept: “Information Hiding”
Key points
The user of an object should have access only to those methods (or data) that are essential
Unnecessary implementation details should be hidden from the user
In Java/C++, use classes and access modifiers (public, private, protected)
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10. CSE_PROGRAMMING PARADIGM_CS206
Inheritance
Inheritance:
programming language feature that allows for the implicit definition of variables/methods for a class through an existing class
Subclass relationship
B is a subclass of A
B inherits all definitions (variables/methods) in A
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11. CSE_PROGRAMMING PARADIGM_CS206
Abstraction
OOP is about abstraction
Encapsulation and Inheritance are examples of abstraction
What does the verb “abstract” mean?
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12. CSE_PROGRAMMING PARADIGM_CS206
Reuse
Inheritance encourages software reuse
Existing code need not be rewritten
Successful reuse occurs only through careful planning and design
when defining classes, anticipate future modifications and extensions
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13. CSE_PROGRAMMING PARADIGM_CS206
Polymorphism
“Many forms”
allow several definitions under a single method name
Example:
“move” means something for a person object but means something else for a car object
Dynamic binding:
capability of an implementation to distinguish between the different forms during run-time
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14. Building Complex Systems
From Software Engineering: complex systems are difficult to manage
Proper use of OOP aids in managing this complexity
The analysis and design of OO systems require corresponding modeling techniques
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15. Object-Oriented Modeling
UML: Unified Modeling Language
OO Modeling Standard
Booch, Jacobson, Rumbaugh
What is depicted?
Class details and static relationships
System functionality
Object interaction
State transition within an object
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16. Some UML Modeling Techniques
Class Diagrams
Use Cases/Use Case Diagrams
Interaction Diagrams
State Diagrams
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17. Example: Class Diagram
Borrower
Book
0..1
0..3
currBorr
bk[]
public class Borrower {
Book bk[]; …
public Borrower() {
bk = new Book[3]; }
public class Book {
Borrower currBorr; … }
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18. Example: Use Case Diagram
LIBRARY SYSTEM
Facilitate Checkout
Search for Book
Borrower
Librarian
Facilitate Return
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19. Example: Interaction Diagram
2: isAvailable()
Checkout
Screen
:Book
1: borrowAllowed()
3: borrowBook()
4: setBorrower()
:Borrower
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20. Example: State Diagram (Book)
start
Reserved
Borrowed
New
Librarian activates
book as available
Borrower returns book
Available
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21. Object-Oriented Design Models
Static Model
Class Diagrams
Dynamic Model
Use Cases, Interaction Diagrams, State Diagrams, others
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22. CSE_PROGRAMMING PARADIGM_CS206
OO Static Model
Classes and Class Diagrams
Relationships
Association
Aggregation/Composition
Inheritance
Dependencies
Attribute and Method names
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23. CSE_PROGRAMMING PARADIGM_CS206
OO Dynamic Model
Goal: Represent
Object behavior
Object interaction
Traditional/Procedural Dynamic Modeling
Data Flow Diagrams (DFDs)
Problem: Processes separate from data
Need modeling notation that highlight tight relationship between data & processes
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24. DFD Example (Inventory Management)
Accept and Post
Delivery
Delivery info
Transaction
Item Master
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25. OO Counterpart: Object Interaction
new (delivery info)
Encoder
:Transaction
post (item count)
:Item Master
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26. Building an OO Dynamic Model
Identify use cases
Describe each use case through an interaction diagram
For more complex objects, provide a state diagram per class
Derive implied methods (and attributes)
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27. CSE_PROGRAMMING PARADIGM_CS206
What’s Next?
Need to understand the notation
Make sure it helps the software development process
When to use the UML techniques
Primarily when specifying OO design
Formal means of communication across the different software development stages
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28. CSE_PROGRAMMING PARADIGM_CS206
ACTIVITY
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