Which statement about an abstract class is true?

Which statement about an abstract class is true?

• A. It cannot contain any concrete methods
• B. It may contain both abstract and concrete methods
• C. It must implement all interface methods
• D. It cannot have constructors

Answer: (B)

An abstract class is a template you base other classes on, and it can mix behavior: it can declare abstract methods (no body) that subclasses must implement, and it can also provide concrete methods (with a body) that share common behavior. This flexibility is why the statement about being able to contain both abstract and concrete methods is true. It lets a base class define some standard actions while leaving other actions to be defined by specific subclasses. The class can also have fields and constructors to initialize shared state, even though it cannot be instantiated on its own. Think of it as a base blueprint: you want to share common code across multiple related classes but still require certain details to be filled in by each concrete subclass. That’s exactly what mixing abstract and concrete methods achieves. Other options aren’t accurate because an abstract class may indeed include concrete methods, it isn’t required to implement all interface methods (it can leave them abstract or rely on subclasses to implement them), and it can have constructors to initialize common data.

An abstract class is a template you base other classes on, and it can mix behavior: it can declare abstract methods (no body) that subclasses must implement, and it can also provide concrete methods (with a body) that share common behavior.

This flexibility is why the statement about being able to contain both abstract and concrete methods is true. It lets a base class define some standard actions while leaving other actions to be defined by specific subclasses. The class can also have fields and constructors to initialize shared state, even though it cannot be instantiated on its own.

Think of it as a base blueprint: you want to share common code across multiple related classes but still require certain details to be filled in by each concrete subclass. That’s exactly what mixing abstract and concrete methods achieves.

Other options aren’t accurate because an abstract class may indeed include concrete methods, it isn’t required to implement all interface methods (it can leave them abstract or rely on subclasses to implement them), and it can have constructors to initialize common data.