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Chapter 10 Thinking in Objects

Chapter 10 Thinking in Objects. Principle of OOP. Inheritance Abstraction Encapsulation Polymorphism Also know as (APIE). Inheritance and Composition. A class can extend another class. Inheritance implements the “ IS a” relationship between objects

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Chapter 10 Thinking in Objects

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  1. Chapter 10 Thinking in Objects

  2. Principle of OOP • Inheritance • Abstraction • Encapsulation • Polymorphism • Also know as (APIE)

  3. Inheritance and Composition • A class can extend another class. • Inheritance implements the “ IS a” relationship between objects • A class can implements interface, methods members from its parent class.

  4. Inheritance and Composition • Is- A and Has –A • Inheritance VS Composition • Favor Composition • Polymorphism • Interfaces

  5. Is-A and Has-A relationship • Classes depend on another class • Classes are related via Is –A or Has –A relationship • Cat-> Animal = IS-A • Car->Wheel, Engine =Has -A • Train->Wheel,Engine=Has -A • Car,Truck-> Vehicle= Is-A • HAS-A=Composition (compose) IS-A=Inheritance(subtype) • Reuse code

  6. Inheritance (Is-A) • Animal is a base class cat class inheritances from animal Animal Cat

  7. Inheritance Syntax Java Supports only public inheritance A is a Superclass and B is a Subclass

  8. Inheritance Syntax In order to call the constructor of superclass(A) the keyword super is used

  9. Composition (Has-A) • Something is made up of other parts • Car contains wheel and engine • It is also called aggregation car wheel Engine

  10. Composition (Has-A):aggregation Composition(HAS-A) simply mean use of instance variables that are references to other objects. For example: Maruti has Engine, or House has Bathroom

  11. Composition (Has-A):aggregation

  12. Aggregation Lab

  13. Inheritance Lab • Follow the instructions provided on Lab9

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