Question

Starting Out With Java early Objects by Tony Gladdis

The class to be modified is found in Code Listing 6-29 section on pgs 417-418 in the book 'Starting Out With Java early Objects by Tony Gladdis the 5th Edition'

7. RetailItem Class Modification

Modify this chapter’s RetailItem class (which uses an inner class named CostData) to include accessor and mutator methods for getting and setting an item’s wholesale and retail cost. Demonstrate the methods in a program.

Thanks

Answer 1

Hi,

Please find the answer below:

Program
---------

// Retail Item Java Class

package chapter6;

import java.text.DecimalFormat;

public class RetailItem
{
   private String description; // Item description
   private int itemNumber;      // Item number
   private CostData cost;       // Cost data
  
   /**
   * RetailItem class constructor
   **/
   public RetailItem(String desc, int itemNum, double wholesale, double retail)
   {
       description = desc;
       itemNumber = itemNum;
       cost = new CostData(wholesale, retail);
   }

   /**
   * RetailItem class toString method
   */
   public String toString() {
       String str; // To hold a descriptive string.
       // Create a DecimalFormat object to format output.
       DecimalFormat dollar = new DecimalFormat("#,##0.00");
       // Create a string describing the item.
       str = "Description: " + description
               + "\nItem Number: " + itemNumber
               + "\nWholesale Cost: $"
               + dollar.format(cost.getWholesale())
               + "\nRetail Price: $"
               + dollar.format(cost.getRetail());
       // Return the string.
       return str;
   }

   /**
   * CostData Inner Class
   */
   private class CostData
   {
       public double wholesale, // Wholesale cost
       retail;     // Retail price
      
       public double getWholesale() {
           return wholesale;
       }

       public void setWholesale(double wholesale) {
           this.wholesale = wholesale;
       }

       public double getRetail() {
           return retail;
       }

       public void setRetail(double retail) {
           this.retail = retail;
       }

       /**
       * CostData class constructor
       */
       public CostData(double w, double r)
       {
           wholesale = w;
           retail = r;
       }
   }
}

//Demo Class

package chapter6;

/**
* This program demonstrates the RetailItem class,  
* which has an inner class.
*/
public class InnerClassDemo
{
   public static void main(String[] args)
   {
       // Create a RetailItem object.
       RetailItem item = new RetailItem("Candy bar", 17789,0.75, 1.5);
       // Display the item's information.
       System.out.println(item);
    }
}

Output:
---------

Description: Candy bar
Item Number: 17789
Wholesale Cost: $0.75
Retail Price: $1.50

Screenshot:
------------

$eclipse-photon-workspace - StartingOutWithJava/src/chapter6/InnerClassDemo,java - Eclipse IDE File Edit Source Refactor Navigate Search Project Run Window Help Quick Access : Console X JuJUnit E. Problems @Javadoc [D. Declaration «terminated> InnerClassDemo [Java Application] C:\Program Files (x86)、Javaure 1.8.0-151 Description: Candy bar Item Number: 17789 Wholesale Cost: $0.75 Retail Price: $1.50 1 package chapter6; 2 4 This program demonstrates the RetailItem class, w 5 which has an inner class. 7 public class InnerClassDemo 9 public static void main(String[ 1 args 6 Ju 10 // Create a Retailltem object. RetailItem itemnew Retailltem( Candy bar // Display the items information System.out.println(item); 12 13 14 15 16 17 18$

Notes:
Added Methods:

public double getWholesale() {
   return wholesale;
}

public void setWholesale(double wholesale) {
   this.wholesale = wholesale;
}

public double getRetail() {
   return retail;
}

public void setRetail(double retail) {
   this.retail = retail;
}

Hope this is helpful.
Let me know if you need more information or have any doubts/clarification in the comments.
Kindly, like the solution if you find it useful.
Thanks,