So I have been working for the past few days on a simple non-GUI tic-tac-toe game and this morning I finally finished. I would like to share some of the things I learned as well as the code for the game.
The game uses 5 methods that comprise all of the logic for the game:
MAIN
initBoard
displayBoard
play
updateGame
I ended up using a 2-D char array as the game board. There was some thought to using an int array but I chose the char so that I could more easily display the ‘x’ and ‘o’.
The logic for determining if the game was over was the most difficult spot for me, specifically the DRAW logic. I began by trying to scan the array for any ‘ ‘ spaces. t the time my logic was not correct and I couldn’t figure out why although eventually I did determine that I was applying the DRAW if there was a single != ‘ ‘ field in the array. Eventually, I moved to a turnCount int that increments by 1 after each user play. If you get to 9 and there is no winner then the game ends in a draw.
The last thing I will mention is that you will see a few variables and some surrounding code that is marked as ‘USED IN TESTING’. I used these fields to help me determine which bit of logic was assigning the invalid ‘win’ flag.
In the coming weeks I plan on tackling some other logic based challenges that increase in difficulty. I will post them here as I complete them.
So here is the tic-tac-toe code:
//BTG 1.22.14
import java.util.Scanner;
public class playGame
{
//creating the game board in a 2-D array
public static char[][] board = new char[3][3];
//public static int[] winningPosition = new int[2]; USED IN TESTING
public static final int rows = 3;
public static final int columns = 3;
//public static int winFlag = 0; USED IN TESTING
static Scanner kbd = new Scanner(System.in);
//constants to represent the contents of the cells
public static final int empty = 0;
public static final int cross = 1;
public static final int zero = 2;
//contents to represent the playing stages of the game
public static final int playing = 0;
public static final int draw = 1;
public static final int won = 2;
public static int turnCount = 0;// USED TO DETERMINE IF GAME ENDS IN DRAW
//public static final int zeroWon = 3;
public static int currentStage; //current Stage of the game
public static int currentPlayer; //player who last moved
public static int currentRow, currentCol; //location of last play
public static void main (String[] args)
{
initBoard(); //sets array values = empty and sets initial currentStage and currentPlayer
displayBoard(); //displays empty initial game board with column and row markers
do
{
play(); //checks for validEntry, collects user input, updates game board
updateGame(); //checks for a winner
displayBoard(); //displays board so next player can make a move
if (currentStage == won && currentPlayer == 1)
System.out.println("Contrats player X, you won!");
if (currentStage == won && currentPlayer == 2)
System.out.println("Contrats player O, you won!");
//USED IN TESTING
//System.out.println(winningPosition[0]+", "+winningPosition[1]);
//System.out.println(winFlag);
//
else if (currentStage == draw)
System.out.println("It's a tie, thanks for playing!");
if (currentPlayer == cross) //switches player
currentPlayer = zero;
else
currentPlayer = cross; //switches player
} while (currentStage == playing);
}//main
public static void initBoard()
{
for(int row = 0; row < 3; row++)
for(int col = 0; col < 3; col++)
board[row][col] = empty; //initial game board, all array fields = empty
currentStage = playing;
currentPlayer = cross; //X always plays first
}//initBoard
public static void displayBoard()
{
System.out.println(" 1 " + board[0][0] + "|" + board[0][1] + "|" + board[0][2]);
System.out.println(" --+-+--");
System.out.println(" 2 " + board[1][0] + "|" + board[1][1] + "|" + board[1][2]);
System.out.println(" --+-+--");
System.out.println(" 3 " + board[2][0] + "|" + board[2][1] + "|" + board[2][2]);
System.out.println(" 1 2 3 ");
}//displayBoard
public static void play()
{
boolean validEntry = false; //boolean for valid entry
do{
if(currentPlayer == cross)
{
System.out.print("\r'X', choose your location (row, column): ");
}
else
{
System.out.print("\r'O', choose your location (row, column): ");
}
int row = kbd.nextInt() - 1; //saves user input for row, array starts at 0
int col = kbd.nextInt() - 1; //saves user input for col, array starts at 0
if (row >= 0 && row < rows && col >= 0 && col < columns && board[row][col] == empty) //acceptable move
{
currentRow = row; //saves value to currentRow for updateGame processing
currentCol = col; //saves value to currentCol for updateGame processing
validEntry = true; //update boolean
if (currentPlayer == cross) //update board to display currentPlayer char value
board[currentRow][currentCol] = 'X';
else //update board to display currentPlayer char value
board[currentRow][currentCol] = 'O';
turnCount = turnCount + 1; //used to determine if game ends in draw
}
else
{
System.out.println("Your attempted play at " +(row+1)+ ", " +(col+1)+ " is not valid. Try again..."); //not a valid user entry
}
}while(!validEntry);
}//play
public static void updateGame()
{
for (int i = 0; i < rows; i++) //CHECKS FOR A WIN IN A ROW
{
if ((board[currentRow][0] == board[currentRow][1] && board[currentRow][1] == board[currentRow][2]) && board[currentRow][0] != empty) {
currentStage = won;
// USED IN TESTING
//winningPosition[0] = currentRow;
//winningPosition[1] = currentCol;
//winFlag = 1;
//
}
}
for (int j = 0; j < columns; j++) //CHECKS FOR A WIN IN A COLUMN
{
if ((board[0][currentCol] == board[1][currentCol] && board[1][currentCol] == board[2][currentCol]) && board[0][currentCol] != empty) {
currentStage = won;
// USED IN TESTING
//winningPosition[0] = currentRow;
//winningPosition[1] = currentCol;
//winFlag = 2;
//
}
}
//CHECKS FOR DIAGONAL WIN
if ((board[0][0] == board[1][1] && board[1][1] == board[2][2]) && board[2][2] != empty) {
currentStage = won;
// USED IN TESTING
//winningPosition[0] = currentRow;
//winningPosition[1] = currentCol;
//winFlag = 3;
//
}
//CHECKS FOR OTHER DIAGONAL WIN
if ((board[0][2] == board[1][1] && board[1][1] == board[2][0]) && board[0][2] != empty){
currentStage = won;
// USED IN TESTING
//winningPosition[0] = currentRow;
//winningPosition[1] = currentCol;
//winFlag = 4;
//
}
//DRAW
if(turnCount == 9 && currentStage == playing)
currentStage = draw;
}//updateGame
}//class
