Chapter 13.8, Problem 13.8.2CP

Explanation of Solution

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.

Legal abstract class:

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 that is declared within the abstract class must be declared without braces and followed by a semicolon.

Interface:

Interface is a reference type in Java, which contains a collection of abstract methods.

An interface needs to the follow certain conditions such as:

• One cannot instantiate an interface.
• Interfaces do not contain any constructors.
• All methods present in the interface are abstracts.
• An interface does not contain any instance field.
• An interface cannot be extended by a class.

Similarities between abstract classes and interfaces:

Some of the similarities between abstract classes and interfaces are mentioned below:

• One cannot create objects for both abstract classes and interfaces.
• All the abstract methods must be overridden by the sub class in both interfaces and interfaces.
• One can create reference variables for both abstract classes and interfaces...