OOP - Inheritance & Polymorphism

What is OOP?

• Object Oriented Procedure

• Object Orientation Programming

• Object Oriented Programming

• Oriented Object Programming

Why OOP is important?

• To create modular software

• To reduce development time as it can be reused easily

• To create faster application

• To minimize bugs as easier to create unit test to a small or atomic methods

What are the main features of OOP?

• 1) Inheritance

  2) Encapsulation

  3) Data Abstraction

  4) Polymorphism

• 1) Inheritance

  2) Encapsulation

  3) Interface

  4) Polymorphism

• 1) Inheritance

  2) Class & Objects

  3) Data Abstraction

  4) Polymorphism

• 1) Inheritance

  2) Encapsulation

  3) Design pattern

  4) Polymorphism

What are class & object?

• 1) class - where keyword 'class' is used to define an object

  2) object - is when class is used in the program

• 1) class - a user defined data type with its data members and functions

  2) object - an instance of a class where memory is allocated

• 1) class - an instance of object where memory is allocated

  2) object - a user defined data type with its data members and functions

• 1) class & object can be used interchangeably. It is same thing where a user defined data type with its data members and functions

What is inheritance?

• Hiding the internal details or mechanics of how an object does something for security reasons.

• A contract to follow without going into implementation

• It is a mechanism where you can to derive a class from another class for a hierarchy of classes that share a set of attributes and methods.

• It is an instance of a class where a class can have multiple instances with different attributes values

What is Polymorphism?

• Association is a relationship between two objects

• The composing object holds an external link to the composing classes, and therefore composition is loosely bound.

• The subclass did not inherit a private method’s properties, and therefore it cannot be overridden.

• A class that can take on multiple forms.

What are type of inheritance?

• Single Inheritance, Multiple Inheritance

• Hierarchical Inheritance, Single Inheritance, Multiple Inheritance

• Hybrid Inheritance, Single Inheritance

• Hierarchical Inheritance, Hybrid Inheritance, Single Inheritance, Multiple Inheritance, Multilevel Inheritance

Why Java doesn't support multiple inheritance?

• It is too complicated to be implemented by JVM

• It is to avoid ambiguity of inheritance

• Multiple inheritance will slow down JAVA application performance

• JVM unable to automatically do garbage collection of multiple inheritance and making JAVA application produce memory leak.

When to use inheritance?

• When there a IS relationship

• When there a HAS relationship

• When the methods between classes are similar

• When the class name are similar

When to use Polymorphism?

• When there is a need to have multiple inheritance

• When there is a need to change the class purpose

• When the class have so many methods

• When there is a need to add the class purpose while retaining its original purpose