Interface Cart

All Known Implementing Classes:
StoreCart
public interface Cart
Represents a shopping cart that holds item orders.

A Cart manages a collection of ItemOrder objects and calculates the total cost based on whether the customer has a store membership. The cart ensures that only one order exists per unique Item - adding a new order for an existing item replaces the previous order.

Version:
Winter 2026
Author:
Charles Bryan

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Interface
    Description
    static final record 
    Cart.CartSize
    A record representing the size of a shopping cart.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    add(ItemOrder theOrder)
    Adds an order to the shopping cart.
    BigDecimal
    calculateTotal()
    Calculates the total cost of all items in the shopping cart.
    void
    clear()
    Removes all orders from the shopping cart.
    Cart.CartSize
    getCartSize()
    Returns the current size of the shopping cart.
    void
    setMembership(boolean theMembership)
    Sets whether the customer has a store membership.

  • Method Details

    • add

      void add(ItemOrder theOrder)
      Adds an order to the shopping cart.

      If an order for the same item already exists, it is replaced with the new order. If the order quantity is 0, the item is removed from the cart entirely.

      Parameters:
      theOrder - the ItemOrder to add to the cart
      Throws:
      NullPointerException - if theOrder is null

    • setMembership

      void setMembership(boolean theMembership)
      Sets whether the customer has a store membership.

      Membership status affects pricing - members receive bulk discounts on eligible items.

      Parameters:
      theMembership - true if the customer has a membership, false otherwise

    • calculateTotal

      BigDecimal calculateTotal()
      Calculates the total cost of all items in the shopping cart.

      The total is calculated by summing the cost of each ItemOrder, taking into account the membership status. The returned value has a scale of 2 and uses HALF_EVEN (banker's) rounding.

      Returns:
      the total cost of the shopping cart

    • clear

      void clear()
      Removes all orders from the shopping cart.

    • getCartSize

      Cart.CartSize getCartSize()
      Returns the current size of the shopping cart.
      Returns:
      a CartSize record containing the number of unique item orders and the total quantity of all items