Chapter 8, Problem 13E

Explanation of Solution

 Implementation of the derived class “CombinedDiscount”:

 The implementation of the “CombinedDiscount” class derived from the “DiscountPolicy” abstract class is given below:

• • Declare the “p1”, and “p2” variables.
• • Define the constructor.
  • ○ Set the values to the declared variables.
• • Define the “computeDiscount” method.
  • ○ Declare the required variables.
  • ○ Call the “computeDiscount” method with different variables.
  • ○ Return the maximum value by checking “discount1” and “discount2” values. 
• • Define the main method.
  • ○ Create the objects for the “CombinedDiscount”, “BuyNItemsGetOneFree”, and “BulkDiscount” classes.
  • ○ The “for” loop through 1 to10 numbers.
    • ■ Call the “computeDiscount” method with objects and display the output.

 The implementation of the “BulkDiscount” class derived from the “DiscountPolicy” abstract class is given below:

• • Declare the “min”, and “percentOff” variables.
• • Define the constructor.
  • ○ Set the values to the declared variables.
• • Define the “computeDiscount” method.
  • ○ If the purchase count is less than minimum, then calculate the “discount” value.
  • ○ Otherwise make “discount” as 0.
• • Finally return the “discount” value.
• • Define the main method.
  • ○ Create an object for the “BulkDiscount” class.
  • ○ Call the “computeDiscount” method with different parameters and display the output.

 The implementation of the “BuyNItemsGetOneFree” class derived from the “DiscountPolicy” abstract class is given below:

• • Declare the “x” variable.
• • Define the constructor.
  • ○ Set the values to the declared variable.
• • Define the “computeDiscount” method.
  • ○ Declare the required variables.
  • ○ Calculate the “a” and “discount” values.
  • ○ Return the “discount” value.
• • Define the main method.
  • ○ Create an object for the “BuyNItemsGetOneFree” class.
  • ○ The “for” loop through 1 to10 numbers.
    • ■ Call the “computeDiscount” method with the parameter and display the output.

The creation of the abstract class “DiscountPolicy” is given below:

• • Declare the abstract method “computeDiscount” along with the two parameters “count” and “itemCost”.
  • ○ This method compute and return the discount for the purchase of a given number of single item.

 Program:

 Filename: CombinedDiscount.java

//definition of "CombinedDiscount" class

public class CombinedDiscount extends DiscountPolicy

{

    //declare the required variables 

    private DiscountPolicy p1;

    private DiscountPolicy p2;

    //definition of constructor

public CombinedDiscount(DiscountPolicy first, DiscountPolicy second )

    {

        //set the values

        p1 = first;

        p2 = second;

    }

    //definition of "computeDiscount" method

public double computeDiscount(int count, double itemCost)

    {

        //declare the required variables

        double discount1;

        double discount2;

        //call the methods with different variables

discount1 = p1.computeDiscount(count, itemCost);

discount2 = p2.computeDiscount(count, itemCost);

        //check the condition

        if(discount1 > discount2)

            //return the value

            return discount1;

        //otherwise

        else

            //return the value

            return discount2;

    }

    //definition of main method

    public static void main(String[] args)

    {

        //create the objects for the classes

DiscountPolicy buy = new BuyNItemsGetOneFree(3);

DiscountPolicy bulk = new BulkDiscount(5, 30...