OCA Java SE 8 Class Design - OCA Mock Question Class Design 18








Question

Which of the following is true about a concrete subclass? (Choose all that apply)

  1. A concrete subclass can be declared as abstract with abstract key word.
  2. A concrete subclass must implement all inherited abstract methods.
  3. A concrete subclass must implement all methods defined in an inherited interface.
  4. A concrete subclass cannot be marked as final.
  5. The abstract methods cannot be overridden by a concrete subclass.




Answer



B.

Note

Concrete classes are not abstract, A is incorrect.

A concrete class must implement all inherited abstract methods, B is correct.

C is incorrect since a superclass may have implemented an inherited interface.

Concrete classes can be both final and not final, so D is incorrect.

Abstract methods must be overridden by a concrete subclass, so E is incorrect.