CS 231: Project #1

Title image Fall 2019

Monte-Carlo Simulation: Blackjack

The main purpose of this project is to give you practice building classes in Java. To do this, we'll simulate a simple version of the card game Blackjack. The objects in a card game include: a Card, a Deck, a Hand, and Game. You'll make a class for each one, connecting them together as appropriate. We'll also start to make use of a few of the many Java library classes.


For this assignment you will implement classes to represent a card, a hand, a deck, and the game Blackjack. The result will be a text-based version of the game that runs in the terminal. You are free to make the game more complex as an extension.

The purpose of the assignment is not to create a Blackjack game for people to play, however, but to study the properties of Blackjack, given a particular rule set, when played over many hands. You are using CS to study the properties of a system defined by a set of rules.

More information about Blackjack.

Basic Blackjack Rules

The link above contains an extensive description of the full rules of Blackjack. For this project, you are required to implement only a simplified rule set. You can implement more of the rules as part of project extensions.

There will be only two players in the game: the player and the house. In our simplified rule set, an ace is worth 11 points. Play should use the following procedure.

  1. The player and the house should each receive two cards dealt from a deck
  2. The player should play their entire turn before the dealer.
    • The player should calculate the value of their hand (the sum of the card values) and choose whether to take a card (hit) or stop at the current value (stand).
    • If the player chooses to hit, then if the new value of their hand is greater than 21, the player loses (busts). If the value is less than 21, the player repeats the process until they stand or bust.
  3. If the player did not bust, the dealer plays.
    • The dealer will continue to take a card (hit) until the value of their hand is 17 or greater.
    • If the dealer busts, then the player wins.
  4. If player and dealer both avoided a bust, then the hand with the highest value wins the game. If both hands are of equal value, then the hand is a tie (push).

When playing Blackjack, the deck is usually not shuffled between each game. Instead, the deck is shuffled when it gets below a certain number of cards. For example, when there are fewer than 26 cards (out of 52), then the deck should be reshuffled. Therefore, shuffling should not be done every game, but should be an action that is conditioned on the number of cards left in the deck. How often the deck is shuffled will affect game play because it affects the probabilities of certain cards appearing.

The Card Class

Create a java class called Card, which should hold all information unique to the card. For this assignment, it needs to hold only the value of the card, which must be in the range 1-11. The Card class should have the following methods. In addition, make a main method that uses each of the class methods.

The Hand Class

Create a java class called Hand, which should hold a set of cards. You can use an ArrayList (import java.util.ArrayList) to hold the Card objects. The class should have at least the following methods.

The Deck Class

Create a java class called Deck, which should hold a set of cards and be able to shuffle and deal the cards. You should use an ArrayList to hold the cards. The class should support the following methods.

The Blackjack Class

Create a class called Blackjack that implements a simple version of the card game. The class will need to have fields for a Deck, a Hand for the player, and a Hand for the dealer. The main function for the Blackjack class should implement one complete game.

Use the main function of your Blackjack class to test the above functions. Make sure they are working properly by dealing two hands and then calling the playerTurn and dealerTurn functions, printing out the game state and making sure the rules are correctly implemented.

Create a function to play a single game.

Update your main function so it creates a Blackjack object and then uses it to play three games with verbose being true. Make sure your game function is working correctly.

Storing Game Output

Once you have completed the above four classes, generate a printout of three different games. You can send output to a file using the greater than symbol on the command line. For example, the command

java Blackjack > mygames.txt

would play a game and send it to the file mygames.txt.


Make one more class called Simulation. This class should have only a main function that executes 1000 games of Blackjack. The code should create and re-use a single Blackjack object. It should keep track of how many games the player wins, how many the dealer wins, and many are pushes. Print out the total in the end both as raw numbers and as percentages.


Projects are your opportunity to learn by doing. They are also an opportunity to explore and try out new things. Rather than list out every activity for a project, the defined part of each project will be about 85% of the assignment. You are free to stop there and hand in your work. If you do all of the required tasks and do them well, you will earn a B/B+.

To earn a higher grade, you can undertake one or more extensions. The difficulty and quality of the extension or extensions will determine your final grade for the assignment. Extensions are your opportunity to customize the assignment by doing something of interest to you. Each week we will suggest some things to try, but you are free to choose your own.

A common question is "how much is an extension worth?" The answer to that question depends on the extension, how well it is done, and how far you pushed it. As teachers, we prefer to see one significant extension, done well, where you explore a topic in some depth. But doing 2-3 simpler extensions is also fine, if that's what you want to do. Choose extensions that you find interesting and challenging.

The following are a few suggestions on things you can do as extensions to this assignment. You are free to choose other extensions, and we are happy to discuss ideas with you.

  1. Create a new function in your Blackjack class called playerTurnInteractive() that uses input from the terminal to control the player's actions. Then create a new class Interactive that lets you play Blackjack on the terminal.
  2. Add in more of the rules for Blackjack. For example, an Ace (value 11 in the default case above) can have the value 1 or 11, whichever is more advantageous. If you add in the Ace rule, then you will also want to take into account a real Blackjack (2 cards totaling 21) when evaluating the winning hand. A Blackjack beats a 21 with more than 2 cards. See how these rules affect the simulation results.
  3. Make your game use 6 decks, and reshuffle if only 1 deck is left. Play the game 1000 times, and observe how many games the player wins, how many the dealer wins, and many are pushes. Compare with using only a single deck.
  4. Run the simulation with different decision rules for the player and see how it affects the outcome percentages over many games (>= 1000).
  5. Add a type of betting strategy to the simulation and see if the player can win money even while losing more games than winning.
  6. Try running the simulation with different numbers of games and see how variable the results are. For example, run the simulation using M games (e.g. M = 100) and do this N times (e.g. N = 10). Then calculate the standard deviation of the results. Then you can plot the standard deviation versus the number of games (M) in the simulation to see how the results stabilize as you use a larger number of games.
  7. For any assignment, a good extension will be to implement a Java class yourself and demonstrate that it has the same functionality as the Java class. For example, you could implement your own ArrayList class for this assignment.
  8. Another good extension for any assignment is to identify in comments when dynamically allocated memory is being "lost." Dynamic memory is any memory created with a new command. Indicate the line of code in which the last reference to an object referencing dynamic memory is removed.)


Your report should have a simple format.


Make your report for the project a wiki page in your personal space. If you have questions about making a wiki page, stop by a professor's office or ask in lab.

Once you have written up your assignment, give the page the label:


You can give any wiki page a label using the label field at the bottom of the page. The label is different from the title.

Do not put code on your writeup page or anywhere it can be publicly accessed. To hand in code, put it in your folder on the Courses fileserver. Create a directory for each project inside the private folder inside your username folder. Please use a naming convention like project01 for your project folders.