Question

Please see the java code below and amend it according to these requirements:

* Do not remove any of the code within the public interface to the class, only add code to test the additional functionality

*Limit items in each instance

*Allow the last item entered to be deleted

The CashRegister class should be modified to limit the number of items that can be added to an instance of the CashRegister. The limit should be declared as a constant in such a way that all instances of the CashRegisterFixedSize have the same limit. The CashRegisterFixedSize class should also have a new instance method, undo(), that removes the last item entered into an instance.

Hints: To implement the additional functionality required, it is recommended that you use an array to store each item’s price within the CashRegisterFixedSize class.

You should adapt the count variable so it can be used to set the index of the array – this will be used store each entry, calculate the total price and when removing the last entered item. The getTotal() method will need to be modified to calculate the total of all values stored in the array. A loop construct is ideal for this. When implementing the undo()method, the value stored in the variable count should be considered.

The code:

public class CashRegister
{
private int itemCount;
private double totalPrice;
public void addItem (double price)

{
itemCount ++;
totalPrice = totalPrice + price;
}
public void clear ()
{
itemCount = 0;
totalPrice = 0;
}

public double getTotal()
{
return totalPrice;
}
  
public int getCount()
{
return itemCount;
}
public CashRegister()
{
itemCount = 0;
totalPrice = 0;
}
}

Answer 1

Hi,

Please find the java classes below:

CashRegisterFixedSize.java

//----------------------------------------------
//CashRegisterFixedSize.java
//----------------------------------------------
public class CashRegisterFixedSize {
   //constant LIMIT of number of items
   public static final int LIMIT = 5;

   //instance variables
   double itemPrices[];
   private int itemCount;
   private double totalPrice;

   //Constructor
   public CashRegisterFixedSize() {
       itemPrices = new double[LIMIT];
       itemCount = 0;
       totalPrice = 0;
   }

   //---------------------------------------
   // addItem() method
   //----------------------------------------
   public void addItem(double price) {
       try {
       itemCount++;
       totalPrice = totalPrice + price;
       itemPrices[itemCount] = price;
       }catch(ArrayIndexOutOfBoundsException ae) {
           System.out.println("Register full!!");
       }
       catch(Exception e) {
          
       }
   }

   //---------------------------------------
   // clear() method
   //----------------------------------------
   public void clear() {
       itemPrices = new double[LIMIT];
       itemCount = 0;
       totalPrice = 0;
   }

   //---------------------------------------
   // getTotal() method
   //----------------------------------------
   public double getTotal() {
       return totalPrice;
   }

   //---------------------------------------
   // getCount() method
   //----------------------------------------
   public int getCount() {
       return itemCount;
   }

   //---------------------------------------
   // undo() method
   //----------------------------------------
   public void undo() {
       if (itemCount > 0)
           itemCount--;
   }
}

//////////////////////////////////////////////

TestDriver.java

import java.util.Scanner;

//--------------------------------
// TestDriver.java
//---------------------------------
public class TestDriver {

   public static void main(String[] args)
   {
       Scanner input = new Scanner(System.in);
       CashRegisterFixedSize crfs = new CashRegisterFixedSize();
       System.out.println("Enter item price: ");
       double price = input.nextDouble();
       crfs.addItem(price);
       System.out.println("Enter item price: ");
       price = input.nextDouble();
       crfs.addItem(price);

       System.out.println("Number of items =: " + crfs.getCount());
       System.out.println("Total cost =: " + crfs.getTotal());

       System.out.println("Enter item price: ");
       //Exception
       price = input.nextDouble();
       crfs.addItem(price);

       System.out.println("Number of items =: " + crfs.getCount());
       System.out.println("Total cost =: " + crfs.getTotal());
   }
}

/////////////////////////////////////////

Screenshot

Sample Output

Enter item price:
100
Enter item price:
200
Number of items =: 2
Total cost =: 300.0
Enter item price:
550
Number of items =: 3
Total cost =: 850.0

--------------------------------------------------

Hope this helps.