Question

I tried to debug it but I have no clue what code I’m loosing. Mind checking up for me? I want to add Item Names, price and quantity into ITEM[] array but when I try to print , it doesn’t return anything

item.java

import java.text.NumberFormat;

public class Item {
    private String name;
    private double price;
    private int quantity;

    public Item(String itemName, double itemPrice, int numPurchased) {
        name = itemName;
        price = itemPrice;
        quantity = numPurchased;
    }

    public String toString() {
        NumberFormat fmt = NumberFormat.getCurrencyInstance();
        return (name + "\t" + fmt.format(price) + "\t" + quantity + "\t"
                + fmt.format(price * quantity));
    }

    public double getPrice() {
        return price;
    }

    public String getName() {
        return name;
    }

    public int getQuantity() {
        return quantity;
    }

}

ShoppingCart.java

import java.text.NumberFormat;
public class ShoppingCart {
private int itemCount; // total number of items in the cart
private double totalPrice; // total price of items in the cart
private int capacity; // current cart capacity
private Item[] cart = new Item[capacity];

// -----------------------------------------------------------
// Creates an empty shopping cart with a capacity of 5 items.
// -----------------------------------------------------------
public ShoppingCart()
{
capacity = 5;
itemCount = 0;
totalPrice = 0.0;
}

// -------------------------------------------------------
// Adds an item to the shopping cart.
// -------------------------------------------------------
public void addToCart(String itemName, double price, int quantity)
{if(itemCount==cart.length)
 increaseSize();
else{
cart[itemCount]=new Item(itemName, price, quantity);
totalPrice += (totalPrice * quantity);
itemCount++;
}
}
// -------------------------------------------------------
// Returns the contents of the cart together with
// summary information.
// -------------------------------------------------------

public String toString()
{
NumberFormat fmt = NumberFormat.getCurrencyInstance();
String contents = "\nShopping Cart\n";
contents += "\nItem\t\tUnit Price\tQuantity\tTotal\n";
for (int i = 0; i < itemCount; i++)
contents += cart[i].toString() + "\n";
contents += "\nTotal Price: " + fmt.format(totalPrice);
contents += "\n";
return contents;
 }
// ---------------------------------------------------------
// Increases the capacity of the shopping cart by 3
// ---------------------------------------------------------
private void increaseSize()
{Item[] temp = new Item[cart.length + 3];
for (int num = 0; num < cart.length; num++)
{
temp[num] = cart[num];
cart = temp;

}

}



}

Shopping1.java

import java.util.Scanner;
public class Shopping1 {


 public static void main(String[] args)
{
 String answer="y";
 ShoppingCart cart = new ShoppingCart();
 while(answer=="y")
 {
 System.out.println("Enter the Name, Price, and Quantity of Item:");
 Scanner scan = new Scanner (System.in);
 String name = scan.next();
 double price = scan.nextDouble();
 int quantity = scan.nextInt();

 cart.addToCart(name, price, quantity);

 String printout = cart.toString();
 System.out.println(printout);
 System.out.println("Do you want to continue? y/n");
 Scanner ans = new Scanner (System.in);
 answer = ans.next();
 }
 System.out.println("thank you !");
}
}

My output was:

Enter the Name, Price, and Quantity of Item:
yuvin
3
2

Shopping Cart

Item        Unit Price  Quantity    Total

Total Price: MYR0.00

Do you want to continue? y/n
n
thank you !

While I was expecting some return of the array which I just inserted

Answer 1

the line

private Item[] cart = new Item[capacity];

is executed prior to the constructor, therefore capacity will be zero at that time and you will get an array without space for elements …

//edit:

additionally there is a flaw in that addToCart method …

if (itemCount==cart.length) is true, the item you are about to add is discarded, because you only increase the array size … you should increase the array size and then add the item …