SOLID Principles of Object Oriented and Agile Design

README.md

https://www.youtube.com/watch?v=TMuno5RZNeE

Encapsulation ?

• OO weaken encapsulation by introducing private, public, protected

Inheritance ?

• why Java doesn't have inheritance ? Diamond problem

Polymorphism

• https://medium.com/@shanikae/polymorphism-explained-simply-7294c8deeef7

getChar
putChar

Polymorphism is the one thing in OOP that solves the problems of a bad code which are rigidity, fragility and non-usability

Single Responsibility Principle (SRP)

• responbility: sources of change

employee
  calcPay()     // CFO
  reportHours()  // COO
  writeEmployee()  // CTO
// This class has 3 responbilities

Open/Closed Principle

modules should be open for extension, close for modification

• for eg: when data source changed from rdb to file, we don't need to change the method
• no switch statement

Liskov (LSP)

Rectangle <- Square

• square is not substitubale for rectangle
• that violates LSP and will add if/else to code

Interface Segregation Principle

• Small interface instead of fat
• compose if necessary

Dependency Inversion Principle (DIP)

• new Keywork is glue
• https://deviq.com/principles/dependency-inversion-principle