Checking for draw in TicTacToe

**arhzz** · June 6th, 2020, 07:01 PM

So after some thought about my code, I forgot that a draw could also occur,and I havent implemented that in my code.So here I am.Now the way of determining if a draw has happened should be pretty simple.First check if the board is full (all the fields are initialised) and second check if there is a winner, if not a draw happend.So I tried to do exactly that I created a method to check if the board was full;

 
public static boolean isBoardFull() {
	for(int i = 0; i < col; i++) {
		for(int j = 0; j < row; j++) {
			if(board[i][j] == EMPTY) {
				return false;
			}
		}
	}
	return true;
}

And I went to implement this method in the rest of my code.Now since I'm here you can assume that something went wrong and this is what is going wrong.After every input it prints out draw.Although it should only do it when the board is full.So my guess is something is wrong with this method, but I'll post the entire code so that you can see how I'm implementing it

 
public class TicTacToe {
	public static int row,col;
	public static char[][] board = new char[3][3];
	public static char turn = 'X';
	public static final int EMPTY = 0;
 
	public static void main(String[] args) {
		for(int i = 0; i < 3; i++) {
			for(int j = 0; j < 3; j++) {
				board[i][j] = '_';
			}
		}
		Play();
	}
 
	public static void printBoard() {
	for(int i = 0; i < 3; i++) {
		Out.println();
		for(int j = 0; j < 3; j++) {
			if(j == 0){
				Out.print("| ");
			}
			Out.print(board[i][j] + " | ");
		}
	}
	Out.println();
 
}
 
 
public static void Play() {
	boolean playing = true;
	printBoard();
	Out.println();
	int nOfTurns = 1;
	Out.println("Turn: " + nOfTurns);
 
	while(playing){
		Out.println();
		Out.println("Player:" +" "+ turn);
		Out.print("Enter a row:");
		row = readNumber();
		Out.print("Enter a coloumn:");
		col = readNumber();
		do {
			if(isTaken(row,col)) {
				Out.print("That cell is taken,please enter another cell:");
				row = readNumber();
				col = readNumber();
			}
		}while(isTaken(row,col));
		board[row][col] = turn;
		nOfTurns++;
		Out.println();
		Out.println("Turn: "+ nOfTurns);
		if(GameOver(row,col)) {
			playing = false;
			Out.println("Player" +" "+turn +" "+"has won!");
		}
		printBoard();
 
		if(isBoardFull()) {
			Out.println("Draw");
		}
 
		if(turn == 'X') {
			turn = 'O';
		}else{
			turn = 'X';
		}
 
}
}
public static boolean GameOver(int rowMove,int colMove) {
	if(board[0][colMove] == board[1][colMove] && board[0][colMove] == board[2][colMove]){
		return true;
	}else if(board[rowMove][0] == board[rowMove][1] && board[rowMove][0] == board[rowMove][2]) {
		return true;
	}else if(board[0][0] == board[1][1] && board[0][0] == board[2][2] && board[1][1] != '_') {
		return true;
	}else if(board[0][2] == board[1][1] && board[0][2] == board[2][0] && board[1][1] != '_') {
		return true;
	}else
		return false;
}
 
 
public static int readNumber() {
	boolean isValid = false;
	int number;
	do {	
 
	number = In.readInt() - 1;
 
	if (!In.done()) {
        Out.println("Input must be a valid number");
        In.readLine(); 
      } else if (number < 0 || number > 2) {
        Out.println("The number is not in the specified range: 1-3");
      } else {
        isValid = true;
      }
    } while (!isValid);
 
    return number;
  }
 
public static boolean isTaken(int row, int col) {
	return board[row][col] != '_';
}
 
public static boolean isBoardFull() {
	for(int i = 0; i < col; i++) {
		for(int j = 0; j < row; j++) {
			if(board[i][j] == EMPTY) {
				return false;
			}
		}
	}
	return true;
}
 
}

**Norm** · June 6th, 2020, 07:16 PM

Time for some debugging to see what the code is doing. Add some print statements inside the loop that print out the values of i and j and the contents of the board at i and j.

**arhzz** · June 6th, 2020, 07:23 PM

Aight I'll give it a shot

**arhzz** · June 7th, 2020, 08:46 AM

So after a good night sleep,and a few hours of coding.I have come up with this;

 
public class TicTacToe {
	public static int row,col;
	public static char[][] board = new char[3][3];
	public static char turn = 'X';
 
	public static void main(String[] args) {
		for(int i = 0; i < 3; i++) {
			for(int j = 0; j < 3; j++) {
				board[i][j] = '_';
			}
		}
		play();
	}
 
	public static void printBoard() {
	for(int i = 0; i < 3; i++) {
		Out.println();
		for(int j = 0; j < 3; j++) {
			if(j == 0){
				Out.print("| ");
			}
			Out.print(board[i][j] + " | ");
		}
	}
	Out.println();
 
}
 
 
public static void play() {
	boolean playing = true;
	printBoard();
	Out.println();
	int nOfTurns = 1;
	Out.println("Turn: " + nOfTurns);
 
	while(playing){
		Out.println();
		Out.println("Player:" +" "+ turn);
		Out.print("Enter a row:");
		row = readNumber();
		Out.print("Enter a coloumn:");
		col = readNumber();
		do {
			if(isTaken(row,col)) {
				Out.print("That cell is taken,please enter another cell:");
				row = readNumber();
				col = readNumber();
			}
		}while(isTaken(row,col));
		board[row][col] = turn;
		nOfTurns++;
		Out.println();
		Out.println("Turn: "+ nOfTurns);
		if(gameOver(row,col)) {
			playing = false;
			Out.println("Player" +" "+turn +" "+"has won!");
		}
		printBoard();
		if(gameOver(row,col) && isTaken(row,col)) {
			Out.println("Draw!");
			playing = false;
		}
		if(turn == 'X') {
			turn = 'O';
		}else{
			turn = 'X';
		}
 
}
}
public static boolean gameOver(int rowMove,int colMove) {
	if(board[0][colMove] == board[1][colMove] && board[0][colMove] == board[2][colMove]){
		return true;
	}else if(board[rowMove][0] == board[rowMove][1] && board[rowMove][0] == board[rowMove][2]) {
		return true;
	}else if(board[0][0] == board[1][1] && board[0][0] == board[2][2] && board[1][1] != '_') {
		return true;
	}else if(board[0][2] == board[1][1] && board[0][2] == board[2][0] && board[1][1] != '_') {
		return true;
	}else {
		return false;
}
 
}
public static int readNumber() {
	boolean isValid = false;
	int number;
	do {	
 
	number = In.readInt() - 1;
 
	if (!In.done()) {
        Out.println("Input must be a valid number");
        In.readLine(); 
      } else if (number < 0 || number > 2) {
        Out.println("The number is not in the specified range: 1-3");
      } else {
        isValid = true;
      }
    } while (!isValid);
 
    return number;
  }
 
public static boolean isTaken(int row, int col) {
	return board[row][col] != '_';
}
 
public static boolean isBoardFull() {
	if(isTaken(row,col)) {
		return true;
	}else{
		return false;
	}
}
 
}

As you can see I've changed my boardIsFull method.Now the issue is not that it prints out draw after every move it is that it doent print draw at all.Even when I reached the end(all the fields are covered) the game does not stop.What am I doing wrong?

**Norm** · June 7th, 2020, 08:55 AM

There is a basic problem in the code using the global variables: row and col. These variables should NOT be global. By global I mean at the class level. Their values are dependent on the context where they are used. They should be declared at the local level inside a method where their values are used. If a method needs their values, they should be passed to the method as arguments.

Change the code by removing row and col as global variables and have them be declared where they are needed and passed as needed.

**arhzz** · June 7th, 2020, 09:14 AM

Did it, but how is that gonna help?

 
public class TicTacToe {
	public static char[][] board = new char[3][3];
	public static char turn = 'X';
 
	public static void main(String[] args) {
		for(int i = 0; i < 3; i++) {
			for(int j = 0; j < 3; j++) {
				board[i][j] = '_';
			}
		}
		play();
	}
 
	public static void printBoard() {
	for(int i = 0; i < 3; i++) {
		Out.println();
		for(int j = 0; j < 3; j++) {
			if(j == 0){
				Out.print("| ");
			}
			Out.print(board[i][j] + " | ");
		}
	}
	Out.println();
 
}
 
 
public static void play() {
	int row,col;
	boolean playing = true;
	printBoard();
	Out.println();
	int nOfTurns = 1;
	Out.println("Turn: " + nOfTurns);
 
	while(playing){
		Out.println();
		Out.println("Player:" +" "+ turn);
		Out.print("Enter a row:");
		 row = readNumber();
		Out.print("Enter a coloumn:");
		 col = readNumber();
		do {
			if(isTaken(row,col)) {
				Out.print("That cell is taken,please enter another cell:");
				row = readNumber();
				col = readNumber();
			}
		}while(isTaken(row,col));
		board[row][col] = turn;
		nOfTurns++;
		Out.println();
		Out.println("Turn: "+ nOfTurns);
		if(gameOver(row,col)) {
			playing = false;
			Out.println("Player" +" "+turn +" "+"has won!");
		}
		printBoard();
		if(!gameOver(row,col) && isBoardFull()) {
			Out.println("Draw!");
			playing = false;
		}
		if(turn == 'X') {
			turn = 'O';
		}else{
			turn = 'X';
		}
 
}
}
public static boolean gameOver(int rowMove,int colMove) {
	if(board[0][colMove] == board[1][colMove] && board[0][colMove] == board[2][colMove]){
		return true;
	}else if(board[rowMove][0] == board[rowMove][1] && board[rowMove][0] == board[rowMove][2]) {
		return true;
	}else if(board[0][0] == board[1][1] && board[0][0] == board[2][2] && board[1][1] != '_') {
		return true;
	}else if(board[0][2] == board[1][1] && board[0][2] == board[2][0] && board[1][1] != '_') {
		return true;
	}else {
		return false;
}
 
}
public static int readNumber() {
	boolean isValid = false;
	int number;
	do {	
 
	number = In.readInt() - 1;
 
	if (!In.done()) {
        Out.println("Input must be a valid number");
        In.readLine(); 
      } else if (number < 0 || number > 2) {
        Out.println("The number is not in the specified range: 1-3");
      } else {
        isValid = true;
      }
    } while (!isValid);
 
    return number;
  }
 
public static boolean isTaken(int row, int col) {
	return board[row][col] != '_';
}
 
public static boolean isBoardFull() {
        boolean isFull = true;
 
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (board[i][j] == '-') {
                    isFull = false;
                }
            }
        }
 
        return isFull;
    }
 
}

**Norm** · June 7th, 2020, 09:19 AM

how is that gonna help?

It forced you to rewrite the isBoardFull method.
I see that more changes were made than just the global variables.
What happens now when the code is executed?
If there are problems, copy the full contents of the command prompt window and paste it here.
Add some comments where the problems are describing what is wrong and what should be different.

**arhzz** · June 7th, 2020, 11:11 AM

I've got it now, here is the code should work.Thanks Norm,once again.This is my pre-last (I dont know if that word exists but I think you get it) assignment in my
programming class and if I get a positive Note, I will pass so wish me luck!

Here is the code;

 
public class TicTacToe {
	public static char[][] board = new char[3][3];
	public static char turn = 'X';
 
	public static void main(String[] args) {
		for(int i = 0; i < 3; i++) {
			for(int j = 0; j < 3; j++) {
				board[i][j] = '_';
			}
		}
		play();
	}
 
	public static void printBoard() {
	for(int i = 0; i < 3; i++) {
		Out.println();
		for(int j = 0; j < 3; j++) {
			if(j == 0){
				Out.print("| ");
			}
			Out.print(board[i][j] + " | ");
		}
	}
	Out.println();
 
}
 
 
public static void play() {
	int row,col;
	boolean playing = true;
	printBoard();
	Out.println();
	int nOfTurns = 1;
	Out.println("Turn: " + nOfTurns);
 
	while(playing){
		Out.println();
		Out.println("Player:" +" "+ turn);
		Out.print("Enter a row:");
		 row = readNumber();
		Out.print("Enter a coloumn:");
		 col = readNumber();
		do {
			if(isTaken(row,col)) {
				Out.print("That cell is taken,please enter another cell:");
				row = readNumber();
				col = readNumber();
			}
		}while(isTaken(row,col));
		board[row][col] = turn;
		nOfTurns++;
		Out.println();
		Out.println("Turn: "+ nOfTurns);
		if(gameOver(row,col)) {
			playing = false;
			Out.println("Player" +" "+turn +" "+"has won!");
		}
		printBoard();
		if(!gameOver(row,col) && isBoardFull()) {
			Out.println("Draw!");
			playing = false;
		}
		if(turn == 'X') {
			turn = 'O';
		}else{
			turn = 'X';
		}
 
}
}
public static boolean gameOver(int rowMove,int colMove) {
	if(board[0][colMove] == board[1][colMove] && board[0][colMove] == board[2][colMove]){
		return true;
	}else if(board[rowMove][0] == board[rowMove][1] && board[rowMove][0] == board[rowMove][2]) {
		return true;
	}else if(board[0][0] == board[1][1] && board[0][0] == board[2][2] && board[1][1] != '_') {
		return true;
	}else if(board[0][2] == board[1][1] && board[0][2] == board[2][0] && board[1][1] != '_') {
		return true;
	}else {
		return false;
}
 
}
public static int readNumber() {
	boolean isValid = false;
	int number;
	do {	
 
	number = In.readInt() - 1;
 
	if (!In.done()) {
        Out.println("Input must be a valid number");
        In.readLine(); 
      } else if (number < 0 || number > 2) {
        Out.println("The number is not in the specified range: 1-3");
      } else {
        isValid = true;
      }
    } while (!isValid);
 
    return number;
  }
 
public static boolean isTaken(int row, int col) {
	return board[row][col] != '_';
}
 
public static boolean isBoardFull() {
        boolean isFull = true;
 
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (board[i][j] == '_') {
                    isFull = false;
                }
            }
        }
 
        return isFull;
    }
 
}

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