/**
 * Title: Playing Tic Tac Toe no Graphics
 * Author: Kay A. Robbins
 */

public class TicTacToe  {
   protected static final int DEFAULT_BOARD_SIZE = 3;
   private static final char BOARD_EMPTY_MARKER = '-';
   private char [][] myBoard;
   private int myBoardSize;
   private boolean myXTurn;  // true if it is X's turn to play
   private char myWinner; // Holds winner ('X', 'O', 'N')
   private int myNumberMoves;  // Contains number of moves

   // Constructors
   public TicTacToe() {
      this(DEFAULT_BOARD_SIZE);
   }

   public TicTacToe(int size) {
      myBoardSize = size;
      myXTurn = true;
      myWinner = 'N';
      myNumberMoves = 0;
      initializeBoard();
   }

   // Accessors
   public int getBoardSize() {
      return myBoardSize;
   }

   public int getNumberMoves() {
      return myNumberMoves;
   }

   public char getWinner() {
      return myWinner;
   }

   public boolean isXTurn() {
      return myXTurn;
   }

   public char getElement(int row, int col ) {
      return myBoard[row][col];
   }

   public void printBoard() {
      System.out.println("After " + myNumberMoves + " moves the board is:");
      for (int row = 0; row < myBoardSize; row++) {
         for (int col = 0; col < myBoardSize; col++)
            System.out.print(myBoard[row][col] + " ");
         System.out.println();
      }
   }

   // Modifiers
   /**
    * If move is valid (in range and not already set)
    * make the move, check for winner and return true.
    * Otherwise return false.
    */
   public boolean play (int row, int column) {
      if (myWinner != 'N')
         return false;
      if (row < 0 || row >= myBoardSize || column < 0 || column >= myBoardSize)
         return false;
      if (myBoard[row][column] != BOARD_EMPTY_MARKER)
         return false;
      if (myXTurn)
         myBoard[row][column] = 'X';
      else
         myBoard[row][column] = 'O';
      myNumberMoves++;
      myXTurn = !myXTurn;
      if (checkForWinner('X'))
         myWinner = 'X';
      else if (checkForWinner('O'))
         myWinner = 'O';
      return true;
   }

   // Private helpers --- these will be very important for clean code
   private void initializeBoard() {
      myBoard = new char [myBoardSize] [myBoardSize];
      for (int row = 0; row < myBoardSize; row++)
         for (int col = 0; col < myBoardSize; col++)
            myBoard[row][col] = BOARD_EMPTY_MARKER;

   }
   // returns true if all entries in row r match c
   private boolean checkRow(int row, char c) {
      for (int col = 0; col < myBoardSize; col++)
         if (myBoard[row][col] != c)
            return false;
      return true;
   }

   private boolean checkColumn(int col, char c) {
      for (int row = 0; row < myBoardSize; row++)
         if (myBoard[row][col] != c)
            return false;
      return true;
   }

   private boolean checkDiagonal(char c) {
      for (int row = 0; row < myBoardSize; row++)
         if (myBoard[row][row] != c)
            return false;
      return true;
   }

   private boolean checkBackDiagonal(char c) {
      for (int row = 0; row < myBoardSize; row++)
         if (myBoard[row][myBoardSize-1 - row] != c)
            return false;
      return true;
   }

   private boolean checkForWinner(char c) {
      for (int i = 0; i < myBoardSize; i++) {
         if (checkRow(i,c))
            return true;
         else if (checkColumn(i, c))
            return true;
      }
      return checkDiagonal(c) || checkBackDiagonal(c);
   }
}

/*
 * TicTacToeGraphics: TicTacToe class extended for graphics
 */
import java.applet.Applet;
import java.awt.*;

public class TicTacToeGraphics extends TicTacToe {
   private static final Color X_COLOR = Color.green;
   private static final Color O_COLOR = Color.blue;
   private static final Color B_COLOR = new Color(255, 255, 200);
   private static final Color BLACK = Color.black;
   public int boxWidth = 70;
   public int boxHeight = 70;

   // Constructors
   public TicTacToeGraphics() {
      this(DEFAULT_BOARD_SIZE);
   }

   public TicTacToeGraphics(int size) {
      super(size);
   }

   // drawX: draw two lines in the square making an "X"
   private void drawX(int i, int j, Graphics g) {
      g.setColor(BLACK);
      int xCen = i*boxWidth + boxWidth/2;
      int yCen = j*boxHeight + boxHeight/2;
      int r = boxWidth/3;
      g.drawLine(xCen - r, yCen - r, xCen + r, yCen + r);
      g.drawLine(xCen - r, yCen + r, xCen + r, yCen - r);
   }

   // drawO: draw a circle in the square making an "O"
   private void drawO(int i, int j, Graphics g) {
      g.setColor(BLACK);
      int xCen = i*boxWidth + boxWidth/2;
      int yCen = j*boxHeight + boxHeight/2;
      int r = boxWidth/3;
      g.drawOval(xCen - r, yCen - r, 2*r, 2*r);
   }

   // displayBoard: display graphical version of board in applet
   public void displayBoard(Graphics g) { // need graphics class
      for (int i = 0; i < getBoardSize();  i++) {
         int xpos = i * boxWidth;
         for (int j = 0; j < getBoardSize(); j++) {
            int ypos = j*boxHeight;
            char c = getElement(i, j);
            if (c == 'X') {
               g.setColor(X_COLOR);
               g.fillRect(xpos, ypos, boxWidth, boxHeight);
	       drawX(i, j, g);
	    }
            else if (c == 'O') {
               g.setColor(O_COLOR);
               g.fillRect(xpos, ypos, boxWidth, boxHeight);
	       drawO(i, j, g);
	    }
            else {
               g.setColor(B_COLOR);
               g.fillRect(xpos, ypos, boxWidth, boxHeight);
	    }
         }   
      }
      // draw vertical and horizontal lines
      g.setColor(BLACK);
      for (int i = 1; i <= 2; i++) {
         g.drawLine(i*boxWidth,0, i*boxWidth, 3*boxWidth);
         g.drawLine(0, i*boxHeight, 3*boxWidth, i*boxHeight);
      }
   }
}

/*
 * TicTacToeApplet.java: applet for TicTacToe game
 */
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.net.URL;

public class TicTacToeApplet extends Applet implements MouseListener {

    TicTacToeGraphics tttg = new TicTacToeGraphics(3);
    private int mRelX, mRelY; // coords of mouse, returned by mouseReleased
    private int posX, posY; // row and col numbers of mouse position
    public void init() {
        setBackground(Color.white);
        addMouseListener(this); // so it notices the mouse
    }

    // for painting and repainting
    public void paint(Graphics g) {
       tttg.displayBoard(g);
       // must do items below in the proper order
       if (tttg.getWinner() == 'X')
          g.drawString("X wins!", 10, 3*tttg.boxHeight + 30);
       else if (tttg.getWinner() == 'O')
          g.drawString("O wins!", 10, 3*tttg.boxHeight + 30);
       else if (tttg.getNumberMoves() == 9)
          g.drawString("Board Full, No Winner", 10, 3*tttg.boxHeight + 30);
       else if (tttg.isXTurn())
          g.drawString("X's turn to play", 10, 3*tttg.boxHeight + 30);
       else if (!tttg.isXTurn())
          g.drawString("0's turn to play", 10, 3*tttg.boxHeight + 30);
    }

    // do actions as mouse button is released
    public void mouseReleased(MouseEvent e) {
       mRelX = e.getX(); mRelY = e.getY();
       int posX = mRelX/tttg.boxWidth;
       int posY = mRelY/tttg.boxHeight;
       tttg.play(posX, posY);
       repaint();
    }

    // not needed or used except for interface implementation
    public void mousePressed(MouseEvent e) {}
    public void mouseClicked(MouseEvent e) {}
    public void mouseEntered(MouseEvent e) {}
    public void mouseExited(MouseEvent e) {}
}

<html>
<applet code="TicTacToeApplet.class" width=210 height=250>
</applet>
</html>