What is a base class in object-oriented design?

What is a base class in object-oriented design?

• A. A class that cannot be inherited.
• B. A class intended to be used as a utility with static methods.
• C. A class that stores data in private fields.
• D. A class that serves as the basis for other or derived classes.

Answer: (D)

In object-oriented design, the base class is the foundation others build upon through inheritance. It provides common data and behavior that derived classes can reuse and extend, acting as a superclass. This enables code reuse and a consistent interface across related types. For example, a Vehicle base class might define start and stop methods, and specific vehicles like Car or Truck inherit those behaviors while adding their own methods. The idea that a class is simply a utility with static methods doesn’t align with being a base class, since such utility classes aren’t intended to be extended. Similarly, storing data in private fields is a common detail of many classes and doesn’t define a base class, and a class that cannot be inherited is the opposite of what a base class represents.

In object-oriented design, the base class is the foundation others build upon through inheritance. It provides common data and behavior that derived classes can reuse and extend, acting as a superclass. This enables code reuse and a consistent interface across related types. For example, a Vehicle base class might define start and stop methods, and specific vehicles like Car or Truck inherit those behaviors while adding their own methods. The idea that a class is simply a utility with static methods doesn’t align with being a base class, since such utility classes aren’t intended to be extended. Similarly, storing data in private fields is a common detail of many classes and doesn’t define a base class, and a class that cannot be inherited is the opposite of what a base class represents.