Question

I’m sure I remember reading that there is a way to make any subclass of the superclass define certain methods. How do I do it?

In my example, the superclass is Account (and is abstract), and the subclasses are SavingsAccount and CurrentAccount. All subclasses must implement their own withdraw() method.

Answer 1

Define this method in the abstract class.

public abstract <returnType> withdraw();

Then, any class that extends your abstract class will be forced to implement the withdraw method.