~Abstract methods can’t have empty body.} ::3:: Does a subclass that extends an abstract class have to give implementation to all the abstract methods of the superclass? {= Not necessarily if the sub ...

An abstract class is a class that is declared using the keyword ‘abstract’ and contains at least one abstract method (a method with no body). It can also have any number of non-abstract methods. An ...

In Java, polymorphism can be achieved by using interfaces or abstract classes, which define the common behavior of a group of classes, but leave the implementation details to the subclasses.