Chapter 11, Problem 3PE

Explanation of Solution

Program:

File name: “NewspaperSubscription.java”

//Define an abstract class named NewspaperSubscription

public abstract class NewspaperSubscription

{

    //Declare required instance variables

    protected String name;

    protected String address;

    protected double rate;

    //Define required getter function for the

    //instance variable name

    public String getName()

    {

        //Return the value

        return name;

    }

    //Define required setter function for the instance

    //variable name

    public void setName(String n)

    {

        //Set the value of the instance variable name by

        //assigning the value in the function parameter to

        //the variable name

        name = n;

    }

    //Define required getter function for the instance

    //variable address

    public String getAddress()

    {

        //Return the value

        return address;

    }

    //Define the required getter function getRate() for

    //the instance variable rate

    public double getRate()

    {

        //Return the value

        return rate;

    }

    //Declare the prototype of an abstract function setAddress()

    public abstract void setAddress(String s);

}

File name: “PhysicalNewspaperSubscription.java”

//Define a class named PhysicalNewspaperSubscription

//inheriting the class NewspaperSubscription

public class PhysicalNewspaperSubscription extends NewspaperSubscription

{

    //Define the overriden method setAddress()

    public void setAddress(String a)

    {

        //Declare and initialize required Boolean variables

        //to store the result of the condition if the given

        //address includes a digit or not

        boolean hasDigit = false;

        address = a;

        //Traverse the character array using a for each loop

        for(int x = 0; x < a.length(); ++x)

            //If the current character is a digit, then

            //assign true to the variable hasDigit         

            if(Character.isDigit(a.charAt(x)))

                hasDigit = true;

            //If the value of the variable hasDigit is true,

            //then assign 15 to the instance variable rate

            if(hasDigit)

                rate = 15.00;

            //Otherwise, display an appropriate message and

            //assign 0 to the instance variable rate

            else

            {

                rate = 0;

                //Print the result

System.out.print("\nAddress must contain a digit   ");

            }

    }

}

File name: “OnlineNewspaperSubscription.java”

//Define a class named OnlineNewspaperSubscription

//extending the class NewspaperSubscription

public class OnlineNewspaperSubscription extends NewspaperSubscription

{

    //Define the overriden method setAddress()

    public void setAddress(String a)

    {

        //Declare and initialize required Boolean variables

        //to store the result of the condition if the given

        //address includes a sign or not

        boolean hasAtSign = false;

        address = a;

        //Traverse the character array using a for each loop

        for(int x = 0; x < a...