Solid Principles in Java

S.O.L.I.D principle is mainly used to write code in an efficient and effective way so that can be managed easily. Additionally it supports for agile software development.

ü S: Single Responsibility Principle

• Key Idea: One class should have only one responsibility
• Simply define as one class should have one task to do
• This causes to create fewer functions
• Lesser functions lead for easy testing
• Powerful code organization 

ü O: Open Closed Principle

• Key Idea: Software components should only opened to extend, but closed to modify
• This extending can be achieved by inheriting from a class or overwriting the required behaviors from a class or by extending certain behaviors of the class
• This principle recommends using interfaces

ü L: Liskov Substitution Principle

• Key Idea: All derived types should be completely substitutable to the respective base types
• Every sub class or derived class should be substitutable for their parent or base class
• This principle avoids misuse of inheritance by conforming to “is-a” relationship

ü I: Interface Segregation Principle

• Key Idea:  Users should not implement unnecessary methods which will not be used
• According to this principle users should be forced to concern on methods which are not in use
• Very large interfaces are segregated into specific and small interfaces so that users only have to know about the methods that are interested
• These types of segregated interfaces are called role interfaces

ü D: Dependency Inversion Principle

• Key Idea: Depends on abstractions not on concretions
• High level module should not depend on any low level module
• According to this principle, it removes hard coded dependencies so that program can be extendable