In this presentation I talk about Object Oriented Design Concepts and Core concepts in java Class Object Java Access Keywords Abstraction Encapsulation Decomposition Generalization Association - some relation / interaction Aggregation - belongs Composition - contains (whole cannot exist without parts) Polymorphism Cohesion Coupling

1. Object Oriented
Design

2. Java Basics
●
Objects
●
Classes

3. Object Oriented Programming
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Organize code into objects
●
Objects contain attributes and methods

4. Class
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Class describes the structure of an object
●
A class can be used to create objects

5. Class

6. Object
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Object is an instance of the class
●
You can create multiple instances (objects) of
a single class

7. Object

8. Constructor
●
Constructor is used to simplify the creation
of objects

9. Java Access keywords
●
Most commonly used ones are
– public – Allows methods and attributes to be
accessed by anyone inside / outside the class
– private – Allows the methods and attribute
access within the class
– [default] – Allows the methods and attribute
access within the package

10. Java Access keywords

11. Static keyword
●
Static variables and methods belong to the
class itself
●
They can be used without instantiating new
objects

12. Static keyword

13. Main Design Principles
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Abstraction
●
Encapsulation
●
Decomposition
●
Generalization

14. Decomposition
●
Break a component into separate parts
●
Combine parts to make a component
●
Break down a problems into pieces which are
easy to understand and solve

15. Decomposition
●
Association
- some relation / interaction
●
Aggregation
- belongs
●
Composition
- contains (whole cannot exist without parts)

16. Association

17. Aggregation

18. Composition

19. Abstraction
●
Focus on essential features of an object, ignore
unnecessary details
●
Model objects based on their behavior, not on
implementation.
●
This simplifies design and handling
●
Show ‘what’ an object can do without showing
‘how’

21. Encapsulation
●
Hide internal details of an object, expose
only what’s needed through interfaces
●
Protect the internal state of an object from
unauthorized access

22. Encapsulation
●
Bundle
– Data, Functions
●
Expose
- Interface
●
Restrict

23. Bundle and Restrict

24. Expose

26. Generalization
●
Extract common beahaviors from two or
more classes and combine them into a
generalized superclass

28. Other OOP concepts
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Inheritance
●
Polymorphism
●
Cohesion
●
Coupling

29. Inheritance
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Establish a parent-child relation
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Child classes inherit attributes and methods
●
Promote code reuse and hierarchy
●
Similar to Generalization

30. Polymorphism
●
Ability of objects to respond differenty and
uniquely to a method call.
●
Allow one interface to be used for different
pourposes
●
Makes code more flexible
●
(This is different from Generalization)

31. Polymorphism

32. Cohesion
●
Represent the clarity of responsibilities of a
module
●
A good design must have high cohesion

33. Cohesion

34. Coupling
●
Measures the complexity of connecting a
module to other modules
●
A good design must have low coupling

35. Coupling