This folder contains all the assignments for the Advanced Java Lab (UCSH-605) course, focusing on SOLID principles, Object-Oriented Design, and Java Coding practices.

The given Java code violates SRP (Single Responsibility Principle) and OCP (Open/Closed Principle).
Refactor the code to:

1. Separate concerns properly (SRP)
2. Make it extensible for new storage types without modifying the base class (OCP)

• easy1.java Original code violating SOLID principles → Refactored version following SRP & OCP.

✅ Single Responsibility Principle (SRP) – Ensure each class has a single responsibility.
✅ Open/Closed Principle (OCP) – Allow extension without modifying existing code.

A Penguin class extends Bird, but Bird has a fly() method. This violates LSP because not all birds can fly.

1. Identify the issue in the hierarchy.
2. Refactor the design to follow LSP.
3. Ensure subclasses can replace the base class without breaking behavior.

• easy2.java
  • Before Refactoring → Penguin inherits fly(), violating LSP.
  • After Refactoring → Introduces Bird as an abstract class and CanFly interface.

✅ Liskov Substitution Principle (LSP) – Subclasses must be replaceable without altering system correctness.
✅ Proper Class Hierarchy Design – Use abstraction to define capabilities correctly.

Create a scalable and maintainable payment processing system supporting:

• Credit Card
• PayPal
• Google Pay

✅ Follow SOLID Principles
✅ Allow adding new payment methods without modifying existing code
✅ Use dependency injection for flexibility

PaymentService (Interface)
   ├── CreditCardPayment (Implements PaymentService)
   ├── PayPalPayment (Implements PaymentService)
   ├── GooglePayPayment (Implements PaymentService)
PaymentProcessor
PaymentLogger
PaymentServiceManager
Main

diffass3.java Implements all SOLID principles in a payment system.

✅ Single Responsibility Principle (SRP) – Separate payment processing, logging, and transaction handling.
✅ Open/Closed Principle (OCP) – Allow new payment methods without modifying existing code.
✅ Liskov Substitution Principle (LSP) – Ensure each payment method behaves correctly as a PaymentService.
✅ Interface Segregation Principle (ISP) – Keep interfaces minimal and focused.
✅ Dependency Inversion Principle (DIP) – Depend on abstractions (PaymentService), not concrete implementations.

how_to_run: steps:

- step: Clone the repository
  command: |
    git clone https://github.com/Saiganesh224212/Advanced_Java_Lab.git

- step: Compile Java files
  commands:
    - javac easy1.java
    - javac easy2.java
    - javac diffass3.java

- step: Run Java programs
  commands:
    - java easy1
    - java easy2
    - java diffass3