Help with certain concepts of an online shopping cart

[Mike Corona]

This program extends the earlier "Online shopping cart" program. (Consider first saving your earlier program).

(1) Extend the ItemToPurchase class per the following specifications:

Private fields
String itemDescription - Initialized in empty constructor to "none"
String itemName - Initialized in empty constructor to "none"
int itemPrice - Initialized in empty constructor to 0
int itemQuantity - Initialized in empty constructor to 0
Parameterized constructor to assign item name, item description, item price, and item quantity. (1 pt)
Public member methods
setDescription() mutator & getDescription() accessor (2 pts)
printItemCost() - Outputs the item name followed by the quantity, price, and subtotal
printItemDescription() - Outputs the item name and description
Ex. of printItemCost() output:

Bottled Water 10 @ $1 = $10

Ex. of printItemDescription() output:

Bottled Water: Deer Park, 12 oz.

(2) Create two new files:

ShoppingCart.java - Class definition
ShoppingCartManager.java - Contains main() method
Build the ShoppingCart class with the following specifications. Note: Some can be method stubs (empty methods) initially, to be completed in later steps.

Private fields
String customerName - Initialized in default constructor to "none"
String currentDate - Initialized in default constructor to "January 1, 2016"
ArrayList cartItems
Default constructor
Parameterized constructor which takes the customer name and date as parameters (1 pt)

Public member methods

getCustomerName() accessor (1 pt)
getDate() accessor (1 pt)
addItem()
Adds an item to cartItems array. Has parameter ItemToPurchase. Does not return anything.
removeItem()
Removes item from cartItems array. Has a string (an item's name) parameter. Does not return anything.
If item name cannot be found, output this message: Item not found in cart. Nothing removed.
modifyItem()
Modifies an item's description, price, and/or quantity. Has parameter ItemToPurchase. Does not return anything.
If item can be found (by name) in cart, check if parameter has default values for description, price, and quantity. If not, modify item in cart.
If item cannot be found (by name) in cart, output this message: Item not found in cart. Nothing modified.
getNumItemsInCart() (2 pts)
Returns quantity of all items in cart. Has no parameters.
getCostOfCart() (2 pts)
Determines and returns the total cost of items in cart. Has no parameters.
printTotal()
Outputs total of objects in cart.
If cart is empty, output this message: SHOPPING CART IS EMPTY
printDescriptions()
Outputs each item's description.

Ex. of printTotal() output:

John Doe's Shopping Cart - February 1, 2016
Number of Items: 8

Nike Romaleos 2 @ $189 = $378
Chocolate Chips 5 @ $3 = $15
Powerbeats 2 Headphones 1 @ $128 = $128

Total: $521

Ex. of printDescriptions() output:

John Doe's Shopping Cart - February 1, 2016

Item Descriptions
Nike Romaleos: Volt color, Weightlifting shoes
Chocolate Chips: Semi-sweet
Powerbeats 2 Headphones: Bluetooth headphones

(3) In main(), prompt the user for a customer's name and today's date. Output the name and date. Create an object of type ShoppingCart. (1 pt)

Ex.

Enter Customer's Name:
John Doe
Enter Today's Date:
February 1, 2016

Customer Name: John Doe
Today's Date: February 1, 2016

(4) Implement the printMenu() method. printMenu() has a ShoppingCart parameter, and outputs a menu of options to manipulate the shopping cart. Each option is represented by a single character. Build and output the menu within the method.

If the an invalid character is entered, continue to prompt for a valid choice. Hint: Implement Quit before implementing other options. Call printMenu() in the main() method. Continue to execute the menu until the user enters q to Quit. (3 pts)

Ex:

MENU
a - Add item to cart
d - Remove item from cart
c - Change item quantity
i - Output items' descriptions
o - Output shopping cart
q - Quit

Choose an option: 

(5) Implement Output shopping cart menu option. (3 pts)

Ex:

OUTPUT SHOPPING CART
John Doe's Shopping Cart - February 1, 2016
Number of Items: 8

Nike Romaleos 2 @ $189 = $378
Chocolate Chips 5 @ $3 = $15
Powerbeats 2 Headphones 1 @ $128 = $128

Total: $521

(6) Implement Output item's description menu option. (2 pts)

Ex.

OUTPUT ITEMS' DESCRIPTIONS
John Doe's Shopping Cart - February 1, 2016

Item Descriptions
Nike Romaleos: Volt color, Weightlifting shoes
Chocolate Chips: Semi-sweet
Powerbeats 2 Headphones: Bluetooth headphones

(7) Implement Add item to cart menu option. (3 pts)

Ex:

ADD ITEM TO CART
Enter the item name:
Nike Romaleos
Enter the item description:
Volt color, Weightlifting shoes
Enter the item price:
189
Enter the item quantity:
2

(8) Implement Remove item menu option. (4 pts)

Ex:

REMOVE ITEM FROM CART
Enter name of item to remove:
Chocolate Chips

(9) Implement Change item quantity menu option. Hint: Make new ItemToPurchase object and use ItemToPurchase modifiers before using modifyItem() method. (5 pts)

Ex:

CHANGE ITEM QUANTITY
Enter the item name:
Nike Romaleos
Enter the new quantity:
3

I will also provide the classes I have already worked on. Most of my issues are in the ShoppingCart class and the ShoppingCartManager class. I have also provided comments to briefly explain my learning curve for each method I do not quite understand.

[Mike Corona]

public class ItemToPurchase
{
    private String itemName;
    private String itemDescription;
    private int itemPrice;
    private int itemQuantity;

    public ItemToPurchase()
    {
        this.itemName = "none";
        this.itemDescription = "none";
        this.itemPrice = 0;
        this.itemQuantity = 0;
    }

    public ItemToPurchase(String itemName, String itemDescription, int itemPrice, int itemQuantity)
    {
        this.itemName = itemName;
        this.itemDescription = itemDescription;
        this.itemPrice = itemPrice;
        this.itemQuantity = itemQuantity;
    }
    
    public String getName()
    {
        return itemName;
    }

    public void setName(String itemName)
    {
        this.itemName = itemName;
    }

    public int getPrice()
    {
        return itemPrice;
    }

    public void setPrice(int itemPrice)
    {
        this.itemPrice = itemPrice;
    }

    public int getQuantity()
    {
        return itemQuantity;
    }

    public void setQuantity(int itemQuantity)
    {
        this.itemQuantity = itemQuantity;
    }

    public String getDescription()
    {
        return itemDescription;
    }

    public void setDescription(String itemDescription)
    {
        this.itemDescription = itemDescription;
    }
    
    public void printItemCost()
    {
        int quantityCost = (getPrice() * getQuantity());
        
        System.out.println(getName() + " " + getQuantity() + " @ $" + getPrice() + " = $" + quantityCost);
    }
    
    public void printItemDescription()
    {
        System.out.println(getName() + ": " + getDescription());
    }
    
    
}

[Mike Corona]

import java.util.ArrayList;
import java.util.Scanner;

public class ShoppingCart
{

    private String customerName;
    private String currentDate;
    private ArrayList<ItemToPurchase> cartItems = new ArrayList<>();

    public ShoppingCart()
    {
        this.customerName = "none";
        this.currentDate = "January 1, 2016";
    }

    public ShoppingCart(String customerName, String currentDate)
    {
        this.customerName = customerName;
        this.currentDate = currentDate;
    }

    public void setCustomerName(String customerName)
    {
        this.customerName = customerName;
    }

    public String getCustomerName()
    {
        return customerName;
    }

    public void setDate(String currentDate)
    {
        this.currentDate = currentDate;
    }

    public String getDate()
    {
        return currentDate;
    }

    public void addItem(ItemToPurchase item) //HAVING TROUBLE PASSING OBJECT THROUGH A PARAMETER
    {
        cartItems.add(item);
    }

    public void removeItem(String itemName)
    {

        for (int i = 0; i < cartItems.size(); ++i)
        {
            ItemToPurchase item = cartItems.get(i);
            if (itemName.equals(item.getName()))
            {
                cartItems.remove(i);
            } else
            {
                System.out.println("Item not found in cart. Nothing modified.");
            }
        }

    }

    public void modifyItem(ItemToPurchase item, String itemName) //FIX!! default values for if statement
    {
        for (int i = 0; i < cartItems.size(); ++i)
        {
            item = cartItems.get(i);
            if (itemName.equals(item.getName()))
            {
                cartItems.get(i).setName("");
                cartItems.get(i).setDescription("");
                cartItems.get(i).setPrice(20);
                cartItems.get(i).setQuantity(5);
            } else
            {
                System.out.println("Item not found in cart. Nothing modified.");
            }
        }
    }

    public int getNumItemsInCart()
    {
        int quantity = 0;
        for (int i = 0; i < cartItems.size(); ++i)
        {
            quantity += cartItems.get(i).getQuantity();
        }
        return quantity;
    }

    public int getCostOfCart()
    {
        int costOfCart = 0;
        for (int i = 0; i < cartItems.size(); ++i)
        {
            costOfCart += cartItems.get(i).getPrice();
        }
        return costOfCart;
    }

    public void printTotal() //FIX!!! Not sure if this is what is expected of method
    {
        for(int i = 0; i < cartItems.size(); i++)
        {
            cartItems.get(i).printItemCost();
        }
        System.out.println("Total: $" + getCostOfCart());
    }

    public void printDescription()
    {
        for (int i = 0; i < cartItems.size(); ++i)
        {
            cartItems.get(i).printItemDescription();
        }
    }

    public static void printMenu(ShoppingCart cart) //FIX!! Having trouble with passing an object as a parameter
    {
        System.out.println("MENU\na - Add item to cart");
        System.out.println("d - Remove item from cart");
        System.out.println("c - Change item quantity");
        System.out.println("i - Output items' descriptions");
        System.out.println("o - Output shopping cart");
        System.out.println("q - Quit");
        System.out.println("\nChoose an option: ");

    }

    /*public static void main(String[] args)
    {
        ShoppingCart shop = new ShoppingCart();
        //Scanner input = new Scanner(System.in);

        //TESTER
        shop.addItem();
        shop.addItem();
        //shop.removeItem("none");
        System.out.println("");
        shop.printDescription();
        System.out.println("Quantity of items in cart: " + shop.getNumItemsInCart());
        shop.printTotal();
        
    }*/
}

[Mike Corona]

import java.util.Scanner;

public class ShoppingCartManager
{

    public static void main(String[] args)
    {
        ShoppingCart cart = new ShoppingCart();
        Scanner input = new Scanner(System.in);

        System.out.println("Enter Customer's Name:");
        cart.setCustomerName(input.nextLine());
        System.out.println("Enter Today's Date:");
        cart.setDate(input.nextLine());
        System.out.println("");
        System.out.println("Customer Name: " + cart.getCustomerName());
        System.out.println("Today's Date: " + cart.getDate());

        char choice = 'q';
        do
        {
            cart.printMenu();

            switch (choice)
            {
                case 'a':
                    cart.addItem();
                    break;
                case 'd': //FIX!!
                    System.out.println("Enter item name:");
                    cart.removeItem(input.nextLine());
                    break;
                case 'c':  //FIX!!!
                    cart.getNumItemsInCart();
                    break;
                case 'i':
                    cart.printDescription();
                    break;
                case 'o':
                    cart.printTotal();
                    break;
            }
            choice = input.nextLine().toLowerCase().charAt(0);
        } while (choice != 'q');
    }

}

[Knute Snortum]

Do you have a question to ask?  Or do you want a code review?

[Mike Corona]

Knute Snortum wrote:Do you have a question to ask?  Or do you want a code review?

This code will not compile because it is unfinished. I need help fixing the methods I commented on. To be completely blunt, I need to know how to finish creating the online shopping cart and I ran into issues such as understanding how to properly pass an object through a parameter or understanding what the instructions were actually asking for. I need some outside logical perspective.

[Knute Snortum]

I see you have a few comments that say something like, "Having trouble passing object as parameter."  Can you TellTheDetails? (That's a link)

[Mike Corona]

Alright, to be a bit more detailed in my comments, first I'll ask about the addItem() method.

Instructions are as follows:

addItem()
Adds an item to cartItems array. Has parameter ItemToPurchase. Does not return anything.

My interpretation in code:

public void addItem(ItemToPurchase item) //HAVING TROUBLE PASSING OBJECT THROUGH A PARAMETER
    {
        cartItems.add(item);
    }

If I set the object as a parameter, how do I assign the values of that method? In the manager class I refer back to that method for the menu, but I cannot do anything with it because it only accepts the object as input. This is confusing me greatly.

Ex.

char choice = 'q';
        do
        {
            cart.printMenu();
 
            switch (choice)
            {
                case 'a':
                    cart.addItem(); //Needs an input value.
                    break;
                case 'd': //FIX!!
                    System.out.println("Enter item name:");
                    cart.removeItem(input.nextLine());
                    break;
                case 'c':  //FIX!!!
                    cart.getNumItemsInCart();
                    break;
                case 'i':
                    cart.printDescription();
                    break;
                case 'o':
                    cart.printTotal();
                    break;
            }
            choice = input.nextLine().toLowerCase().charAt(0);
        } while (choice != 'q');
    }

This applies to any other method I created, containing the object as a parameter.

[Knute Snortum]

addItem()
Adds an item to cartItems array. Has parameter ItemToPurchase. Does not return anything.

Hmm.  This is ambiguous to me.  Do you have a class called ItemToPurchase? It looks like you do.  Then your code would look something like this:

ItemToPurchase item = new ItemToPurchase(); // or however you create it
cart.addItem(item);