Real-World Analogy of Null Object Design Pattern

Problem Statement:

Consider a car rental service where customers can choose to rent different types of cars.

• Abstract Dependency: The rental service provides an abstract class or interface called Car that defines the behavior of a car, such as drive() and stop() methods.
• Real Dependency: The rental service offers various car models as concrete implementations of the Car interface, such as Sedan, SUV, and Convertible. These represent real cars that customers can rent.
• Null Object: Sometimes, a customer may request a car model that is not available in the rental service’s fleet. Rather than returning a null reference or raising an error, the rental service could provide a NullCar object that implements the Car interface but doesn’t actually represent any specific car model. This way, the customer can still use the drive() and stop() methods without causing issues.
• Client: The customer renting the car interacts with the rental service’s car objects. They can request a specific car model and use it for their needs. If the requested car model is not available, the rental service provides a NullCar object, ensuring that the customer can still drive and stop the car, even though it doesn’t correspond to a real car model

The Null Object Design Pattern is a behavioral design pattern that is used to provide a consistent way of handling null or non-existing objects. It is particularly useful in situations where you want to avoid explicit null checks and provide a default behavior for objects that may not exist.