Factory Design Pattern

Factory pattern

Polymorphism

extensibility

What is the worst keyword in Java from polymorphism angle

• final
• instanceof
• static

new

• new ClassName() //tight coupling
• So many patterns to fight with new, especially in Spring
• new introduces tight coupling. New is not polymorphic in Java, C++, .Net but it is in Ruby
• Python or Kotlin doesn’t even have new

Golden Rule : interfaces are better than abstract classes

Interfaces can have implementations (default methods) however they cannot have non-final fields

Interfaces cannot carry state but an abstract class carry a state.

Abstract Factory vs. Factory Method

Class vs method

Factory Method : A class or an interface relies on a derived class to provide the implementation whereas the base provides the common behavior

uses inheritance as design tool

uses factory METHOD

Abstract Factory uses delegation as design tool