SOLID_Principles_and_Design_Patterns

Example implementations of SOLID Principles and common Design Patterns

SOLID Principles:

S - Single Responsibility:

• There should never be more than one reason for a class to change.
• Focused, single functionality
• Addresses a specific concern

O - Open Closed:

• Entities (Classes, Modules, Methods, ets.) should be open for extension, but closed for modification
• Open for Extension: Extend existing behavior and
• Closed for Modification: Existing code remains unchanged

L - Liskov Substitution:

• Should be able to substitute base class objects with child class objects and this should not alter behavior or characteristics of the program

I - Interface Segregation:

• Clients should not be forced to depend on interfaces that they do not use
• Signs ofInterface Pollution:
  • Large Interfaces
  • Classes have empty method implementations
  • Method implementations throw UnsupportedOperationException (or similar)
  • implementations return null or default/dummy values

D - Dependency Inversion:

• High level modules should not depend on low level modules
  • Both should depend on abstraction
• Abstraction should not depend on details
  • Details should depend on abstraction

Design Patterns:

1. Creational

• Deal with the process of creating objects of classes

1. Builder

2. Simple Factory

3. Factory

4. Abstract Factory

5. Prototype

6. Singleton

7. Object Pool

2. Structural

• Deal with how classes and objects are arranged or composed

1. Adapter

2. Bridge

3. Decorator

4. Composite

5. Facade

6. Flyweight

7. Proxy

3. Behavioral

• Describe how classes and objects interact and communicate with each other

1. Chain of Responsibility

2. Command

3. Interpreter

4. Mediator

5. Iterator

6. Observer

7. State

8. Strategy

9. Template Method

10. Visitor

11. Null Object