SOLID Principles in Java

This project demonstrates the 5 SOLID principles of Object-Oriented Programming using Java.
Each principle is implemented in its own package with simple, real-world inspired examples.

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📌 SOLID Principles Covered

1. Single Responsibility Principle (SRP)

• A class should have only one reason to change.
• Example: Separation of InvoicePrinter and InvoiceSaver from Invoice.

2. Open/Closed Principle (OCP)

• Classes should be open for extension but closed for modification.
• Example: Adding new Shape types without modifying existing code.

3. Liskov Substitution Principle (LSP)

• Subtypes must be substitutable for their base types.
• Example: Dog and Cat can be used wherever Animal is expected.

4. Interface Segregation Principle (ISP)

• Clients should not be forced to depend on methods they do not use.
• Example: Separate interfaces for Printer, Scanner, Fax.

5. Dependency Inversion Principle (DIP)

• High-level modules should not depend on low-level modules, but on abstractions.
• Example: NotificationService depends on MessageSender interface, not directly on EmailSender.

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