Understanding SOLID Principles in Java Programming

SOLID principles guide object-oriented programming, ensuring code efficiency and maintainability. Each letter represents a key principle:

Single Responsibility: A class should have one, and only one, reason to change. For example, an Employee class that handles emails violates this by deviating from its primary responsibilities.

Open/Closed: Software entities should be open to extension but closed to modification. A class like AreaCalculator that requires changes for new shapes contradicts this. Instead, an interface like IAreaCalculator should be used for extensibility.

Liskov Substitution: Subtypes must be interchangeable with their base types. A Bird class with subclasses Eagle and Ostrich fails if Ostrich cannot truly fly. Separating flying and non-flying birds resolves this issue.

Interface Segregation: Clients should not be forced to depend on interfaces they do not use. An interface like IShapeAreaCalculator that requires Square to implement volume methods is inefficient. Segregating interfaces according to specific needs improves this.

Dependency Inversion: High-level modules should not depend on low-level modules; both should depend on abstractions. An Employee class directly using EmailNotification is inflexible. By depending on a Notification interface, flexibility is ensured.

Adhering to SOLID principles results in software that is robust, adaptable, and easy to maintain.