Design Patterns

This page lists the milestone requirements for Milestone 4 of the CC 410 Restaurant Project. Read the requirements carefully and discuss any questions with the instructors or TAs.


The CC 410 Restaurant Project project for this semester is centered around building a point of sale (POS) system for a fictional restaurant named Game Grub, offering food of all kinds to celebrate our love of games of all kinds.

The fourth milestone involves creating a class to track orders made at the restaurant, a class for combo meals, and more. It also includes many different design patterns to improve the structure of the code.

General Requirements

  • All code must be object-oriented.
    • All executable code must be within a class
      • Python package files such as and are exempt.
    • Classes must be organized into packages based on common usage.
  • All projects must include automation for testing, style checking, and documentation generation.
    • Java: Use Gradle with the application, jacoco, and checkstyle plugins.
    • Python: Use tox configured to use Python 3.10 and a requirements file to install libraries.
  • All code must properly compile and be executable.
    • Java: It must compile and execute using Gradle.
    • Python: It must execute using Python 3.10. Where specified, type hints should be included in the code, and all code should pass a strict Mypy type check.
  • All code submitted must be free of style errors. We will be using the Google Style Guide for each language.
    • Java: Use Checkstyle 10.6.0+ and the Google Style Configuration.
      • You may modify the configuration to allow 4 space indentations instead of 2 space indentations.
    • Python: Use Flake8 with the flake8-docstrings and pep8-naming plugins. Code should conform to PEP 8 style with Google style docstrings.
  • Where specified, code should contain appropriate unit tests that achieve the specified level of code coverage.
    • Java: Use JUnit 5. You may choose to use Hamcrest for assertions.
    • Python: Use pytest. You may choose to use Hamcrest for assertions.
  • Where specified, code should contain appropriate documentation comments following the language’s style guide.
    • In any class that should be documented, every method in that class should have complete documentation comments.
    • Java: Use javadoc to generate documentation.
    • Python: Use pdoc3 to generate documentation.
  • Submissions to Canvas should be tagged GitHub releases that are numbered according to Semantic Versioning.

Assignment Requirements

New Classes

This assignment will add several new classes to the project

Order Class - this class should represent a collection of Item objects that make up an order.

  • It should implement the Iterator Pattern, such that it can be used in a for each loop or enhanced for loop to iterate through all items in the list.
  • It should also support standard collection methods such as:
    • Getting the number of items in the collection
    • Determining if a given instance of an Item object is contained in the collection. Recall that this should use the identity test, not the equality test.
    • Getting a single item from the collection based on the index of that item.
    • Any other standard collection methods that you feel are helpful. See the Collection interface in Java or Emulating Container Types in Python for additional methods that may be useful.
  • It should have the following attributes:
    • A private list of Items, with methods to add and remove items.
      • NOTE - in most languages, the default method to remove an item from a collection will rely on equality testing, not instance testing. So, you may wish to write this method yourself instead of relying on the underlying collection, in order to keep this and the GUI in sync.
    • A private integer representing the order number for this order.
      • It will be generated using the OrderNumberSingleton class discussed below. It should only include a getter.
    • A private static float for the tax rate, which is set to 0.115 (11.5%) by default.
      • It should include static methods to get and set the tax rate, which will be used by all Order objects.
      • The tax rate must always be a valid percentage value ranging from 0.0 to 1.0, inclusive, and this should be enforced by the setter.
  • It should also have getters for these virtual attributes or properties:
    • Subtotal - the total sum of the prices for each item in the order.
    • Tax - the subtotal multiplied by the tax rate.
    • Total - the subtotal plus the tax.
    • Calories - the total number of calories in the order.
  • All dollar amounts should not be rounded to two decimal places by this class. That will be handled later in the GUI.
Combo Class - this class should implement the Item interface, and represent a combo meal consisting of an entree, a side, and a drink.

  • The class should have the following attributes:
    • String Name - the name of the combo
    • A Entree instance - the entree in the combo
    • A Side instance - the side in the combo
    • A Drink instance - the drink in the combo
  • The above attributes should conform to the following:
    • The attributes should have getters and setters.
    • The attributes may be set to null or None in the constructor to represent a combo yet to be configured.
    • The attributes should have a clear method to reset their values back to null or None. You may have a single method, or one for each attribute.
  • The class should have the following static attributes:
    • Float Discount
      • It should have a value .80 ($0.80) by default.
      • It should include a static getter and setter method.
  • The class should also implement the Item interface:
    • A getter for the price, that returns the sum of the prices of each item in the combo.
      • If all items in the combo are populated, the discount is applied to this total. Otherwise, no discount is applied.
    • A getter for the calories that returns the sum of the calories of each item in the combo.
    • A getter for instructions that returns a list containing the following:
      • The name of the combo, if set, as the first entry. If not, it should include “Custom Combo” as the first entry.
      • A second entry stating “$discount Discount Applied” if all items in the combo are present. If not, this entry should not be included.
  • The class should also include the following methods not discussed above:
    • A constructor that accepts a string for the name.
      • The constructor should allow the name to be omitted or set to null or None. The name will only be set by the ComboBuilder class discussed below, but users will also be able to configure a custom combo via the GUI that does not include a name.
      • The constructor should set the other attributes to null or None initially.
    • A getter for all of the items in the combo. It should return a list containing each item that is populated.
    • An implementation of the appropriate method to check for equality between two objects.
      • Two combos are considered equal if their entree, side, drink, and name are equal (they do not have to be the same instances, but each one should be equal).
      • If any attribute in this object is null or None, it is considered equal if the matching attribute is also null or None.
        • This presents a real problem in Java, because calling the equals() method on a null object will result in an exception. So, you’ll have to check if each attribute in this object is null first. If so, and the other object’s attribute is not null, then they are not equal. If this object’s attribute is not null, you can safely call equals() on it, regardless of the other object’s attribute.
Combo Builder - a class that implements the Builder Pattern and Factory Method Pattern to build the available combos described below.

  • It should include a single public static method to build a combo that accepts a string, and builds and returns the Combo object indicated by that string (the name of the combo).
  • For simplicity, it may also include a public static getter for the number of combos available.

You don’t have to create individual classes for the builder pattern in the ComboBuilder class - it is sufficient to just have a private method for building each combo in the class itself. The full Builder pattern is a bit too much boilerplate code for this simple use.

Order Number Singleton - a class that implements the Singleton Pattern to generate new order numbers.

  • The class should have a non-static integer next order number attribute, which is initially set to 1
  • It should have one public static method get next order number that will return the next order number.
    • This method should call a private get instance method to get the actual singleton instance stored as a static attribute in the class.
    • It should access the next order number attribute through that singleton instance.

Updated Classes

There will also be several updates to existing classes.

Menu - update to include the following items:

  • A static getter method for combos that returns all pre-configured combos described below. This method should use the ComboBuilder class discussed below.
  • Update the fullMenu method to include the combos returned from the method listed above.

Documentation Comments

All new and updated classes in this milestone should contain full documentation comments. Every method should be completely documented!

Unit Tests

No new unit tests are required for this milestone. They will be added in the next milestone.

Time Requirements

Completing this project is estimated to require 3-8 hours.


A rough estimate for this milestone would be around 1000 lines of new or updated code. -Russ

Grading Rubric

This assignment will be graded based on the rubric below:

  • New Classes: 90%
    • Order - 30%
    • Combo - 30%
    • ComboBuilder - 15%
    • OrderNumberSingleton - 15%
  • Class Updates: 10%
    • Menu class: 10%

The following deductions apply:

  • Any portion of the project which will not compile (Java), pass a strict type check (Python), or execute properly will be given a grade of 0.
  • Any portion of the project which does not meet the general requirements listed above will have a commensurate amount of points deducted.

This is not an exhaustive list of possible deductions. The instructors will strive to provide reasonable and fair grading, but we can’t predict all possible defects. It is up to the student to ensure that the project is complete and correct before submission.

Code Review

As part of the grading of all assignments in this course, I will be doing a deep dive into a few classes in your code. This will include leaving detailed comments on code style and format in GitHub. I will usually choose various classes to review at random, and any issues found in that class will be verified in other classes of the same type. - Russ


Submit this assignment by creating a release on GitHub and uploading the release URL to the assignment on Canvas. You should not submit this Codio project or mark it as complete in Codio, in case you need to come back to it and make changes later.


Game Night

Jenga Nachos, Catan Skewers, Sorry Soda

Roll the Dice

Yahtzee Poke, Potato Dice, Candy Land Shake

Big Appetite

Chess Chicken Parmesan, Risk Bites, Cranium Coffee

The Winner

Monopoly Bowl, Potato Dice, Sorry Soda