Assignment 3
Objective
This assignment should give you practice with classes, command-line arguments, and
inheritance.
Task
Write a Tic-Tac-Toe game which will be played and drawn with text characters on the console.
Your main program should be in a class called TicTacToe, stored in a file called
• TicTacToe.java
You may build other classes in other files. How exactly you design this program and what
other files you create will be up to you. Everything will be packed up into a runnable jar file at
the end. Each file should have a comment including your name at the top of the file. Each file
should also have appropriate comments throughout.
Requirements
1. Storage and setup: You can design this with as many or as few classes as you like. The game
must begin with the main() method in class TicTacToe. You must use a 3 x 3 twodimensional array to store the game board information (store it as member data of a class,
you can choose the type of storage).
Suggestion: Try to design your classes for re-usability. If you changed things, such as porting
your game logic to a GUI interface, how easy would it be?
Another suggestion: Construct a main “game loop” that runs the game logic until game
over. This will be easier if you set up base class variables for a generic player, then attach
objects for the player types used in a given game using polymorphism.
2. Player options: You should allow the options of two human players, a human player and a
computer player, or two computer players. This will be controlled through command line
options when starting the program. First player will have X, the second player will have O.
The command format for player options is:
java TicTacToe [-c [1|2]]
The “-c” option indicates computer player(s). The optional “1|2” allows the user to specify
which player will be the computer player. Omitting the “-c” option means two human
players (the default). The possible combinations are:
java TicTacToe // two human players
java TicTacToe -c // two computer players
java TicTacToe -c 1 // computer is player 1, human player 2
java TicTacToe -c 2 // human player 1, computer player 2
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If the command is invalid usage (illegal options), print a usage message, as below, then exit
the program:
Usage: java TicTacToe [-c [1|2]]
3. Board output and player interface: The output of the board should be in ASCII text format
and needs to be user friendly. When asking a human player for a move, let them type in just
the number of a square (a single number). Whenever an invalid cell is chosen by a human
player (already filled or out of range), print an error message and have them re-enter.
Player 1 will always be X and will go first (whether human or computer). Player 2 will always
be O. See below for some suggested output.
4. Computer Player Rules: The computer player should not just use random moves. It needs
to follow the following rules, in this order of priority:
(a) If a winning move is available, take it.
(b) If the opponent is threatening a win, block it (Note that if the opponent has two winning
plays, only one can be blocked).
(c) If the center space is available, take it.
(d) Choose randomly between any remaining squares.
Note that with the above logic, it is possible to beat the computer player.
5. End of Game: If somebody wins, determine and print out which player was the winner. If
the game ends with no winner, print out that it was a draw.
6. Randomness: Whenever the computer player has to make a random choice, each choice
must have an equal chance of being picked (so, if there is a choice of 3 squares, you should
pick a random number in a range of 3, etc.). If you try to choose a random number between
1 and 9, then check if the square is available, there is a small chance that your program
could run a long time and never pick a valid square.
Some Suggested Libraries/Classes
• String
• StringBuilder
• java.util.Random
• java.util.Scanner
• java.lang.Integer
Also, notice that there is a good opportunity to use inheritance and polymorphism in the game
play. It also may be useful to create an enum for the space type.
Sample Output
(user input is underlined)
Game Board: Positions:
3
| | 1 | 2 | 3
———– ———–
| | 4 | 5 | 6
———– ———–
| | 7 | 8 | 9
Player 1, please enter a move(1-9): 9
Game Board: Positions:
| | 1 | 2 | 3
———– ———–
| | 4 | 5 | 6
———– ———–
| | X 7 | 8 | 9
Player 1 chooses position 5
Game Board: Positions:
| | 1 | 2 | 3
———– ———–
| O | 4 | 5 | 6
———– ———–
| | X 7 | 8 | 9
Player 1, please enter a move(1-9): 1
Game Board: Positions:
X | | 1 | 2 | 3
———– ———–
| O | 4 | 5 | 6
———– ———–
| | X 7 | 8 | 9
Player 1 chooses position 6
Game Board: Positions:
X | | 1 | 2 | 3
———– ———–
| O | O 4 | 5 | 6
———– ———–
| | X 7 | 8 | 9
Player 1, please enter a move(1-9):
Extra Credit
Add a command line option “-a”, which stands for “advanced.” This option, if used, makes the
computer players take their turns with more advanced logic, as follows:
1. If a winning move is available, take it
2. If the opponent is threatening a winning move, block it
3. Determine which squares can be played that will not eventually result in a loss, and
choose randomly between them
In other words, on the advanced setting, a computer player will always play smart enough
to not lose. On this setting, any game will result in a tie if a human is using the optimal strategy;
otherwise, the computer will win. Exactly how you create the logic for the 3rd part of the
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computer’s logic is up to you, as long as the computer can never lose (which is possible, as TicTac-Toe is a solved game).
Sample command line usage:
java TicTacToe -c 1 -a // player 1 is computer on advanced setting
Note that the -a option only makes sense if the -c option is used. If you do the extra credit, the
usage message would now be:
Usage: java TicTacToe [-c [1|2] [-a]]
Submitting
Pack all of your files (class files and source code) into a fully runnable JAR file called hw3.jar.
The main program that the jar file should execute should be in class TicTacToe. I should be
able to run the main() method from your file with the command:
java -jar hw3.jar
Submit your jar file via the Canvas submission link for assignment 3.
