Assignment 4 C212 FA22
Last modified 2022-10-06 4:30 PM
Learning Objectives
After completing this assignment, students will be proficient in utilizing 2D Arrays,
ArrayLists, and the logic used to manipulate them to solve complex problems.
Summary
The gist of this assignment document's contents are as follows:
● Program Description: Tic-Tac-Toe with 1 or 2 players and replay viewing
● Hints, edge-cases, and design considerations
○ You get starter code this time… here's how to use it (or not)
○ You must use 2D arrays and ArrayLists
○ Why do we have static variables/methods?
● Deliverables & Reminders
○ Use a project named Assignment4, and a class named TicTacToe,
preferably by starting with the starter code project folder.
○ Submit a .zip file that is your compressed project folder.
● Rubric
○ Also visible on Canvas assignment page
● Sample program output
● Changelog
Program Description
Your little brother achieved some amazing results thanks to your program. So you
decide to reward him by making a game for him. In particular, he loves to play tictac-toe with you so you decide to build that.
Furthermore, you want him to be able to compete against the computer as well as
you. Hence, your game is going to have two modes: (i) single player mode (against
the computer) and (ii) two player mode.
In two player mode, your program should first ask the players their names and toss
a coin to decide who goes first. Then the program should ask the users to take turns
playing the game. Ensure that each move is legitimate, and print the game result when
someone wins or when the game ends in a draw.
In one player mode, your program should first ask for the difficulty as well as the
player's name. There can be 3 modes: easy, medium, or hard. Then it should toss a
coin to decide who gets to go first.
In easy mode, the computer just randomly decides a row and column (really dumb)
and keeps doing that until a valid move is found. In hard mode, your program
should be good enough so that the human never wins; instead, the game should
end in a "draw" or "the computer wins." Here is the algorithm you should implement for
the hard AI:
1. Check if there is a winning move available, and if yes, make that move and win.
2. If not, check if there is a winning move available for the opponent, and if yes,
take that spot on the board.
3. If not, then check to see if the center spot is empty. If yes, take that spot on the
board.
4. If not, then see if there are any open corners on the board. If yes, take the first
open corner found on the board.
5. If not, then find any remaining empty spot on the board and take that spot.
Medium should be in between these two. It should not be dumb but not as good as
the hard level. It's up to you how you want to implement the AI for this difficulty as long
as you follow this guideline.
There should be a main menu option to display the last match. As you'll see in the
starter code, this can be achieved by storing each turn of the game in an ArrayList.
Player one and player two refer to the order in which the players enter their names.
Player one gets the 'X' character while player two gets the 'O' character. Player one
does NOT refer to the player who takes the first turn, since it's based on a coin-flip.
When playing one-player mode, the AI will always be player two.
Lastly, the menu should repeat unless the user selects the quit option.
Hints, edge-cases, and design considerations
This is a challenging assignment with many moving parts! It would be a great idea to
start early to leave ample time to visit office hours and get help when you're stuck.
To get you started, this week we provide starter code in the form of an IntelliJ project
folder, which has all the headers of the methods you'd need to implement to create the
program as well as more specific hints for doing so. You are not required to use this
starter code and you may modify it however you wish, such as by adding additional
methods or changing return and parameter types.
You can unzip the starter code file to get a project folder. Then, open this in IntelliJ and
work with it as you would any other project.
Make extensive use of methods to organize your code and break the problem down into
manageable pieces. The starter code contains all the method headers you would need
for this – the solution we wrote has all these methods and no more than these methods
– but feel free to add, modify, or remove them as long as it helps you.
Start with the two-player game, since that'll be most similar to what you're familiar with
and makes testing easier. After you have that, the only challenge with the one-player
game will be implementing the AI algorithms, as the rest of the game logic will carry
over and can be reused.
You must use an ArrayList to store the game history, and you must use a 2D char array
to store a game state.
The starter code has three static variables in the TicTacToe class, which are used to
centrally store what symbols in the game represent the empty space, the player one
symbol, and the player two symbol. Throughout your code, you must refer to these
static variables rather than hard-coding the game to rely on ' ', 'X', and 'O'. You may not
add additional static variables to the class. These are effectively used as configuration
options for the game.
Certain methods in the starter code are marked as private. Since we're only using one
class, there is no functional difference. Later on in the course you'll see why some have
their access from other classes restricted in this way. All methods are static. You'll also
see why when we cover what it means for methods and variables to be static in detail.
Your program should conform to these edge-case expectations regarding user input:
- In every menu, check whether the user's choice of menu option is valid and
inform them if their choice isn't valid.
- When inputting positions on the board, you do not need to handle non-numerical
or non-integer inputs. Assume they will only input integers. However, you should
check that the integers they inputted are valid. This means their input should both
be within the 3x3 grid and should be an unoccupied space. Inform the user if
their input was invalid and which of these two rules it broke.
Deliverables & Reminders
The usual deliverables and reminders apply. Compress and submit your project folder to
Canvas before the deadline (or after with penalty, per the syllabus). The more serious
warnings are listed below, but of course past assignments have more detailed
instructions.
Ensure your submission contains the necessary file(s) and is the correct version of your
code that you want graded. This is your warning. You will not be allowed to resubmit this
assignment after the due date if you submit the wrong file.
Remember that this is graded on accuracy and you are not allowed to collaborate on
your solutions with others. Plagiarism or cheating will be dealt with seriously.
Rubric
A rubric is also available on the assignment page on Canvas, but here is an outline of
the point breakdown for different categories.
➢ (10pts) Code cleanliness, conventions, and comments
○ (10/10pts) for >95% correctness and all required comments
○ (7.5/10pts) for repeated minor mistakes or one egregious mistake, or for
missing either overall or inline comments
○ (5/10pts) for code that is sloppy and hard to understand or is missing all
comments
○ (<=2.5 10pts)="" for="" code="" that="" has="" no="" comments,="" is="" hard="" to="" understand,="">
consistently does not follow Java conventions
➢ (25pts) Two-player game
○ (1pts) for coin-flip that decides who goes first randomly
○ (2pts) for displaying the past game state before a player's turn
○ (8pts) for tracking game history correctly using an ArrayList of game states
■ (-2pts per) for minor oversights like not adding the initial game state
to the game history without handling that design decision in the
replay, etc.
○ (10pts) for ensuring that an inputted move is within game bounds and is
unoccupied, re-prompting for input if invalid, and displaying the reason
why the move is invalid (either out of bounds or already occupied)
○ (2pts) for game ends on a win, displaying winner player's name
○ (2pts) for game ends on a draw
➢ (30pts) One-player game
○ (10pts) for adapting general game behavior from two-player game
■ (1pt) for random first turn
■ (2pts) for displaying game state before player turn
● (-1pt) for displaying the same game state more than once
■ (2pts) for tracking game history using an ArrayList of game states
■ (3pts) for validating user move inputs, warnings, etc.
■ (2pts) for game ending on a win or draw, displaying winner name
○ (5pts) for easy AI that makes a random valid move
○ (5pts) for medium AI smarter than easy but worse than hard
○ (10pts) for hard AI that follows algorithm correctly to never lose
➢ (20pts) Replay last game
○ (7.5pts) for correctly displaying the names of the users and the symbols
they had in the game
■ (-5pts) if the symbols associated with the players aren't always right
○ (1.25pts) for correctly displaying the names of each person who took the
turn in the replay
○ (1.25pts) for correctly displaying the game outcome at the end
○ (10pts) for iterating over the ArrayList to display each turn
➢ (10pts) Menu functionality throughout
○ (2pts) for a menu system that takes user input, executes the appropriate
code on valid entry and warns the user of invalid entry, repeating until user
ends program
○ (3pts) for correct names input collection – the first name should be player
one, the computer should be player two and be given a reasonable name,
for example
○ (3pts) for not executing the replay unless a past game exists
○ (3pts) for repeatedly asking for difficulty before starting the one-player
game
➢ (5pts) for using static/global variables correctly throughout
○ (-1pt) per instance where a symbol was hardcoded rather than referring to
appropriate static class char variable
○ (0pts) for this category if additional static variables are added
Sample program output
Two players, general case with replay display
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: D
No match found.
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: 2
Enter player 1 name: Nazim
Enter player 2 name: Obed
Tossing a coin to decide who goes first!!!
Nazim gets to go first.
| |
-----------
| |
-----------
| |
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 0
X | |
-----------
| |
-----------
| |
Obed's turn:
Obed enter row: 0
Obed enter col: 0
That space is already taken. Try again.
Obed enter row: 0
Obed enter col: 3
That row or column is out of bounds. Try again.
Obed enter row: 1
Obed enter col: 1
X | |
-----------
| O |
-----------
| |
Nazim's turn:
Nazim enter row: 1
Nazim enter col: 0
X | |
-----------
X | O |
-----------
| |
Obed's turn:
Obed enter row: 2
Obed enter col: 0
X | |
-----------
X | O |
-----------
O | |
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 2
X | | X
-----------
X | O |
-----------
O | |
Obed's turn:
Obed enter row: 1
Obed enter col: 2
X | | X
-----------
X | O | O
-----------
O | |
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 1
Nazim wins!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: D
Nazim (X) vs Obed (O)
| |
-----------
| |
-----------
| |
Nazim:
X | |
-----------
| |
-----------
| |
Obed:
X | |
-----------
| O |
-----------
| |
Nazim:
X | |
-----------
X | O |
-----------
| |
Obed:
X | |
-----------
X | O |
-----------
O | |
Nazim:
X | | X
-----------
X | O |
-----------
O | |
Obed:
X | | X
-----------
X | O | O
-----------
O | |
Nazim:
X | X | X
-----------
X | O | O
-----------
O | |
Nazim wins!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: Q
Thanks for playing. Hope you had fun!
Two players, game ends in tie with replay display
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: 2
Enter player 1 name: Nazim
Enter player 2 name: Obed
Tossing a coin to decide who goes first!!!
Obed gets to go first.
| |
-----------
| |
-----------
| |
Obed's turn:
Obed enter row: 1
Obed enter col: 1
| |
-----------
| O |
-----------
| |
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 2
| | X
-----------
| O |
-----------
| |
Obed's turn:
Obed enter row: 0
Obed enter col: 0
O | | X
-----------
| O |
-----------
| |
Nazim's turn:
Nazim enter row: 2
Nazim enter col: 2
O | | X
-----------
| O |
-----------
| | X
Obed's turn:
Obed enter row: 1
Obed enter col: 2
O | | X
-----------
| O | O
-----------
| | X
Nazim's turn:
Nazim enter row: 1
Nazim enter col: 0
O | | X
-----------
X | O | O
-----------
| | X
Obed's turn:
Obed enter row: 2
Obed enter col: 0
O | | X
-----------
X | O | O
-----------
O | | X
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 1
O | X | X
-----------
X | O | O
-----------
O | | X
Obed's turn:
Obed enter row: 2
Obed enter col: 1
It's a draw!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: D
Nazim (X) vs Obed (O)
| |
-----------
| |
-----------
| |
Obed:
| |
-----------
| O |
-----------
| |
Nazim:
| | X
-----------
| O |
-----------
| |
Obed:
O | | X
-----------
| O |
-----------
| |
Nazim:
O | | X
-----------
| O |
-----------
| | X
Obed:
O | | X
-----------
| O | O
-----------
| | X
Nazim:
O | | X
-----------
X | O | O
-----------
| | X
Obed:
O | | X
-----------
X | O | O
-----------
O | | X
Nazim:
O | X | X
-----------
X | O | O
-----------
O | | X
Obed:
O | X | X
-----------
X | O | O
-----------
O | O | X
It's a draw!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: Q
Thanks for playing. Hope you had fun!
One player, playing a game in each mode and watching some replays
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: s
's' is not a valid option.
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: 1
E: Easy
M: Medium
H: Hard
Choose difficulty: f
'f' is not a valid difficulty
E: Easy
M: Medium
H: Hard
Choose difficulty: E
Enter player 1 name: Nazim
Tossing a coin to decide who goes first!!!
Easy Computer gets to go first.
| |
-----------
| |
-----------
| |
Easy Computer's turn:
| |
-----------
| |
-----------
| O |
Nazim's turn:
Nazim enter row: 1
Nazim enter col: 1
| |
-----------
| X |
-----------
| O |
Easy Computer's turn:
| |
-----------
O | X |
-----------
| O |
Nazim's turn:
Nazim enter row: 2
Nazim enter col: 0
| |
-----------
O | X |
-----------
X | O |
Easy Computer's turn:
| |
-----------
O | X |
-----------
X | O | O
Nazim's turn:
Nazim enter row: 0
Nazim enter col: 2
Nazim wins!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: D
Nazim (X) vs Easy Computer (O)
| |
-----------
| |
-----------
| |
Easy Computer:
| |
-----------
| |
-----------
| O |
Nazim:
| |
-----------
| X |
-----------
| O |
Easy Computer:
| |
-----------
O | X |
-----------
| O |
Nazim:
| |
-----------
O | X |
-----------
X | O |
Easy Computer:
| |
-----------
O | X |
-----------
X | O | O
Nazim:
| | X
-----------
O | X |
-----------
X | O | O
Nazim wins!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: 1
E: Easy
M: Medium
H: Hard
Choose difficulty: M
Enter player 1 name: Nazim
Tossing a coin to decide who goes first!!!
Medium Computer gets to go first.
| |
-----------
| |
-----------
| |
Medium Computer's turn:
O | |
-----------
| |
-----------
| |
Nazim's turn:
Nazim enter row: 2
Nazim enter col: 2
O | |
-----------
| |
-----------
| | X
Medium Computer's turn:
O | |
-----------
O | |
-----------
| | X
Nazim's turn:
Nazim enter row: 2
Nazim enter col: 0
O | |
-----------
O | |
-----------
X | | X
Medium Computer's turn:
O | |
-----------
O | |
-----------
X | O | X
Nazim's turn:
Nazim enter row: 1
Nazim enter col: 2
O | |
-----------
O | | X
-----------
X | O | X
Medium Computer's turn:
O | | O
-----------
O | | X
-----------
X | O | X
Nazim's turn:
Nazim enter row: 1
Nazim enter col: 1
O | | O
-----------
O | X | X
-----------
X | O | X
Medium Computer's turn:
O | O | O
-----------
O | X | X
-----------
X | O | X
Medium Computer wins!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: 1
E: Easy
M: Medium
H: Hard
Choose difficulty: H
Enter player 1 name: Obed
Tossing a coin to decide who goes first!!!
Hard Computer gets to go first.
| |
-----------
| |
-----------
| |
Hard Computer's turn:
O | |
-----------
| |
-----------
| |
Obed's turn:
Obed enter row: 1
Obed enter col: 1
O | |
-----------
| X |
-----------
| |
Hard Computer's turn:
O | O |
-----------
| X |
-----------
| |
Obed's turn:
Obed enter row: 0
Obed enter col: 2
O | O | X
-----------
| X |
-----------
| |
Hard Computer's turn:
O | O | X
-----------
| X |
-----------
O | |
Obed's turn:
Obed enter row: 1
Obed enter col: 0
O | O | X
-----------
X | X |
-----------
O | |
Hard Computer's turn:
O | O | X
-----------
X | X | O
-----------
O | |
Obed's turn:
Obed enter row: 2
Obed enter col: 2
O | O | X
-----------
X | X | O
-----------
O | | X
Hard Computer's turn:
It's a draw!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: D
Obed (X) vs Hard Computer (O)
| |
-----------
| |
-----------
| |
Hard Computer:
O | |
-----------
| |
-----------
| |
Obed:
O | |
-----------
| X |
-----------
| |
Hard Computer:
O | O |
-----------
| X |
-----------
| |
Obed:
O | O | X
-----------
| X |
-----------
| |
Hard Computer:
O | O | X
-----------
| X |
-----------
O | |
Obed:
O | O | X
-----------
X | X |
-----------
O | |
Hard Computer:
O | O | X
-----------
X | X | O
-----------
O | |
Obed:
O | O | X
-----------
X | X | O
-----------
O | | X
Hard Computer:
O | O | X
-----------
X | X | O
-----------
O | O | X
It's a draw!
1. Single player
2. Two player
D. Display last match
Q. Quit
What do you want to do: Q
Thanks for playing. Hope you had fun!
Changelog
If any corrections, clarifications, etc. are made to the assignment after its release, they
will be listed here. Any changes more substantial than simply fixing typos will get
corresponding Canvas announcements. That way, you don't need to keep checking
whether updates have occurred.
● 10/6 4:30PM: Reworded "(-1pt) for displaying game state before AI turn" to
"(-1pt) for displaying the same game state more than once"