🔖 Background Information
Tic-tac-toe is a game for two players who take turns marking the spaces in a three-by-three grid with an “X” or “O”. The player who puts three of their marks in a horizontal, vertical, or diagonal row is the winner. You can see a full writeup of the rules and a bit of game theory behind tic-tac-toe on its Wikipedia page (“Tic-Tac-Toe,” 2024).
🎯 Problem Statement
Implement a human versus human game of tic-tac-toe that can be played on the console.
Note: You will expand on this codebase multiple times throughout the semester in different portfolios.
✅ Acceptance Criteria
You should implement a human vs human game of tic-tac-toe.
- Computer players are not required for this submission.
- Player 1 is “X” and Player 2 is “O”.
- The game is played on a 3 x 3 board.
- This game of tic-tac-toe should implement all the “classic” rules – e.g. players take turns marking the board, three marks in a row wins, etc.
As a tic-tac-toe player, when I start the program, I should see:
- A welcome message for the game.
- A nicely formatted board consisting of a 3 x 3 square grid of cells. The cells should be numbered 1 – 9.
- A prompt to take a move.
As a tic-tac-toe player, after I make a valid move, I should see:
- The board in its updated state with all of the moves taken thus far
- A prompt for the next player to make a move.
- Details for the end of the game if the game is over (see below).
As a tic-tac-toe player, after I make an invalid move, I should see:
- The board in its current state with no additional moves made
- A prompt telling me that my move was invalid and to try again.
When the game ends:
- It should tell me which player won or if the game ended in a draw.
- It should prompt me to play again.
- If I choose to play the game again, it should start a brand new game with a cleared board.
The program should warn a user when an input is invalid. This applies when a user enters a cell position and when a user decides to play again. Some validations include:
- A cell is already taken.
- A string or char input instead of an integer (or vice versa).
- Random or unexpected symbols.
- Random whitespace.
- A decimal number instead of an integer for the cell input.
- No input (just pressing enter).
Your program should not crash from user input!
📋 Dev Notes
Keep the idea of an MVP (minimal viable product) in mind as you write your code. If you have to ask “should I include this feature?”, the answer is probably “no” unless specifically outlined in the Acceptance Criteria.
The goal of the tic-tac-toe project is to build on previous submissions. For portfolios 2 and 3, you will build on this same submission to implement more features. You CANNOT rewrite tic-tac-toe from scratch in future submissions.
🖥️ Example Output
$ gradle run
Welcome to Tic-Tac-Toe!
1 | 2 | 3
-----+-----+-----
4 | 5 | 6
-----+-----+-----
7 | 8 | 9
What is your move? 3
1 | 2 | X
-----+-----+-----
4 | 5 | 6
-----+-----+-----
7 | 8 | 9
What is your move? 258
That is not a valid move! Try again.
What is your move? 4
1 | 2 | X
-----+-----+-----
O | 5 | 6
-----+-----+-----
7 | 8 | 9
What is your move? 4
That is not a valid move! Try again.
What is your move? 6
1 | 2 | X
-----+-----+-----
O | 5 | X
-----+-----+-----
7 | 8 | 9
What is your move? $
That is not a valid move! Try again.
What is your move? 7
1 | 2 | X
-----+-----+-----
O | 5 | X
-----+-----+-----
O | 8 | 9
What is your move? 9
1 | 2 | X
-----+-----+-----
O | 5 | X
-----+-----+-----
O | 8 | X
Player X wins!
Would you like to play again (yes/no)? foobar
That is not a valid entry!
Would you like to play again (yes/no)? no
Goodbye!