What is an abstract function in Java?

The Purpose of Abstract Classes. The purpose of abstract classes is to function as base classes which can be extended by subclasses to create a full implementation . For instance, imagine that a certain process requires 3 steps: The step before the action.

ABSTRACT METHOD in Java, is a method that has just the method definition but does not contain implementation . A method without a body is known as an Abstract Method. It must be declared in an abstract class. The abstract method will never be final because the abstract class must implement all the abstract methods.

To declare an abstract method, use this general form: abstract type method-name(parameter-list); As you can see, no method body is present. Any concrete class(i.e. class without abstract keyword) that extends an abstract class must override all the abstract methods of the class.