Implementing an abstract class when the concrete implementation conforms to the Liskov Substitution Principle is exactly when inheritance does make sense. You w

Implementing an abstract class when the concrete implementation conforms to the Liskov Substitution Principle is exactly when inheritance does make sense. You would do this so that calling code wouldn't need to care that the function required a MySpecialMapClass rather then something that conforms to the AbstractMap interface. However, if you just think that some of the functions in AbstractMap are useful but plan on creating a totally different class that doesn't conform to the interface, then inheritance is inappropriate. Code reuse is not a reason to use inheritance; it is a byproduct of it.