Chapter 8.4, Problem 33STQ

Program Plan Intro

“abstract”:

“abstract” is a keyword or modifier, which is used in the case of class and method.

Purpose of “abstract” class:

An “abstract” class is a class which may or may not include abstract methods and cannot be instantiated, but rather can be sub classed or it must serve as a superclass.

The conditions for a class to be considered as legal “abstract” class are mentioned below:

• If a class includes “abstract” methods, then the class must be declared as “abstract”.
• The “abstract” method is declared within the “abstract” class that must be declared without curly braces and followed by a semicolon.

Example of an “abstract” class:

The example of an “abstract” class is mentioned below:

public abstract class GraphicRectangle {

    // declare fields

    // declare non abstract methods

  abstract void drawRectangle();

}