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Introduction to SOLID Design Principles

SOLID is an acronym for the first five Object-Oriented design (OOD) principles by Robert C. Martin.

Gopi Gorantala
Gopi Gorantala
2 min read


SOLID is an acronym for the first five Object-oriented design (OOD) principles by Robert C. Martin, intended to make the software more understandable, flexible, scalable and maintainable.

These are not "design patterns", but design principles for effective object-oriented design while designing a class structure.

This is generally asked in Java Senior Coding Interviews. Sadly developers don't care about them until they appear for an interview.

Design principles

The 5 design principles are:

  1. Single Responsibility Principle (Keeping components laser focused).
  2. Open-Closed Principle (Evolving code without modifying existing components).
  3. Liskov Substitution Principle (Generating correct relationships between types).
  4. Interface Segregation Principle (Modularizing abstractions).
  5. Dependency Inversion Principle (Decoupling Components)

Learning and knowing these principles will help you design a solid object-oriented software product. Most developers apply them to software components and microservices to build robust and maintainable software.

Each principle is intended to address a different aspect of software design and development, but together they form a comprehensive set of guidelines for building high-quality, flexible software.

Importance of software design principles

They promote good design practices and help developers create flexible, maintainable, and easy-to-understand software.

Java is an object-oriented language, which means that it is designed to model real-world objects and their relationships.

The SOLID principles are guidelines that can help developers create more effective and efficient object-oriented code.

By following the SOLID principles in Java programming, developers can:

  1. Create more modular code: Each SOLID principle promotes modularity by separating concerns and responsibilities. This makes it easier to change and maintain the code over time.
  2. Improve code quality: SOLID principles encourage best practices such as encapsulation, abstraction, and polymorphism. These practices help to create more reusable code.
  3. Promote code reusability: SOLID principles encourage the creation of interfaces and abstract classes, which can be used to define common functionality that can be reused across different parts of the codebase.
  4. Increase code maintainability: SOLID principles make it easier to identify and isolate problems in the code, making it easier to maintain and update.

Overall, following the SOLID principles can help Java developers create software that is more effective, efficient, and maintainable, leading to better software development practices and better software products.


  1. Increased maintainability: SOLID principles promote writing code that is easier to maintain and modify over time.
  2. Improved scalability: SOLID principles help write code handling increased complexity as the application grows.
  3. Better code reuse: SOLID principles lead to writing more modular, reusable, and easily testable code.
  4. Enhanced collaboration: SOLID principles make it easier for developers to understand and work with each other's code.


  1. Steep learning curve: Adopting SOLID principles requires a deep understanding of object-oriented programming, which may be challenging for some developers.
  2. Overhead: Applying SOLID principles may require more time and effort during development.
  3. Rigidity: Strictly adhering to SOLID principles can lead to overly complex code that is difficult to understand and modify.
  4. Inflexibility: SOLID principles are guidelines, not strict rules, but some developers may treat them as such, leading to inflexible code.Introduction
SOLID Design Principles

Gopi Gorantala Twitter

Gopi is an engineering leader with 12+ of experience in full-stack development—a specialist in Java technology stack. He worked for multiple startups, the European govt, and FAANG in India and Europe.


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