SOLID PRINCIPLES IN JAVA

The Single Responsibility Principle states that a class should have only one reason to change. This means each class should only perform one specific task.

Implementation in Java:

• Break down large classes into smaller, focused classes.
• Ensure each class is responsible for a single functionality.

Example: A class handling user authentication should not also manage logging or database connections.

The Open/Closed Principle states that software entities should be open for extension but closed for modification. In Java, this is often achieved using interfaces and abstract classes.

Implementation in Java:

• Use inheritance and polymorphism to extend functionality.
• Avoid changing existing code when adding new features.

Example: Adding new types of payment methods without modifying the existing payment processing code.

The Liskov Substitution Principle states that objects of a superclass should be replaceable with objects of a subclass without affecting the functionality of the program.

Implementation in Java:

• Ensure subclasses do not violate the behavior of the parent class.
• Test polymorphic behavior thoroughly.

Example: A method expecting a base class type should work seamlessly when passed a derived class instance.

The Interface Segregation Principle states that a class should not be forced to implement interfaces it does not use. Instead, create smaller, more specific interfaces.

Implementation in Java:

• Split large interfaces into smaller ones.
• Use multiple specific interfaces for different functionalities.

Example: A "Printer" interface should not force a class to implement both print and scan functionalities if it only prints.

The Dependency Inversion Principle states that high-level modules should not depend on low-level modules; both should depend on abstractions. This promotes loose coupling.

Implementation in Java:

• Depend on interfaces or abstract classes, not concrete implementations.
• Use dependency injection frameworks like Spring to manage dependencies.

Example: A service class depends on an abstraction of a repository interface rather than a specific database implementation.