CIS 1068 Assignment 9
Grocery Shopping List

Posted: Saturday, April 4

Due: Monday, April 13

70 points (+ up to 15 extra credit)

This assignment will give you more practice with implementing your own classes and managing collections using arrays. You'll build a shopping list program with items and estimated prices.

GroceryItem

Implement a class GroceryItem that stores data about an item on your shopping list. It should include the following private fields:

• name: a String describing the item (e.g., "Apples", "Milk")
• quantity: an int representing how many of this item to buy
• estimatedPrice: a double for the estimated price *per unit*
• extra credit: category the kind of item, e.g., "snack", "dairy", "bulk", etc.). It's up to you to decide on the data type

Your class should provide the following public methods:

• A constructor to initialize all fields
• Accessors and mutators for all fields
• increaseQuantity(int amount) and decreaseQuantity(int amount)
• totalEstimatedPrice(): returns quantity * estimatedPrice
• toString(): returns a nicely formatted summary of the item

GroceryList

Implement a class GroceryList to manage a collection of GroceryItem objects.

It should contain the following private fields:

• items[]: an array of GroceryItem
• numItems: number of valid elements currently in the array
• INITIAL_CAPACITY: constant for initial array size

Public methods must include:

• Constructor to initialize array and set numItems to 0
• addItem(): adds a new item, resizing array if necessary
• toString(): prints all items in the list
• find(String name): returns index of item with given name or -1 if not found
• getItem(int index): returns item at given index or null if invalid
• removeItem(int index): removes item at index and shifts remaining items left
• totalQuantity(): returns total quantity across all items
• totalEstimatedCost(): returns sum of totalEstimatedPrice() for all items
• extra credit: itemsInCategory(String category): returns array of items in the given category

// Example usage
GroceryList groceries = new GroceryList();
groceries.addItem(new GroceryItem("Apples", 6, 0.29));
groceries.addItem(new GroceryItem("Milk", 2, 3.49));
System.out.println(groceries);
System.out.println("Total estimated cost: $" + groceries.totalEstimatedCost());

Write a very short driver program to test your code to make sure it's working. You are not required to write JUnit tests.

implementation notes

One of the purposes of this assignment is give you practice managing fixed-sized arrays. Although you may use the Arrays class, please refrain from using ArrayList or any other class in Java's Collections Framework. (We'll get to these soon 🤞.)

shifting list items

Suppose that we have a GroceryList with a capacity of 10 items and contains 4. We can visualize it this way (X represents a null reference):

Suppose that we then purchase item 1 (so it should be removed from the list). Each subsequent item is shifted down one position and a null reference is pulled in from the end.

size, capacity, length, etc.

One common point of confusion is how to count things in the collection.

• The capacity of items[], i.e., the number of things it can hold, is simply items.length
• numItems should contain the number of things that are currently stored in items[]. This could range from 0 to items.length
• INITIAL_CAPACITY is a constant, which is how big items[] is at the time it's created. It is not relevant after the array is created.

what to submit

Upload your .java files to Canvas.

It's a good idea to confirm through the Canvas submission page that what you've intended to submit was uploaded. We will grade what you submit. If you submit a corrupted, empty, or otherwise incorrect file, this is what we'll grade. It is your responsibility to verify through the Canvas submission page that you've submitted the correct files and that they were uploaded properly.

If you're unsure about how to submit, please consult Canvas' tutorial or see us for help.