Thread: Need help please.

So here's what I've got:

 
public class TicTacToeGame {
 
    static int [][] gameboard;
    static final int EMPTY = 0;
    static final int NOUGHT = -1;
    static final int CROSS = 1;
    static void createBoard(int row, int col){
          int gameboard[][]= new int [row][col];
 
    }
 
static int winOrTie(){
        for (int r=0; r<gameboard.length; r++) {
            int x1=gameboard[r][0];
            int x2=gameboard[r][1];
            int x3=gameboard[r][2];
 
            if (x1 == x2 && x2 == x3 && x1 != EMPTY){
                return x1;
        }
        for (int c=0; c<gameboard.length; c++){
            int y1=gameboard[0][c];
            int y2=gameboard[1][c];
            int y3=gameboard[2][c];
 
            if (y1 == y2 && y2 == y3 && y1 != EMPTY){
                return y1;
            }
        }
 
        int z1 = gameboard[0][0];
        int z2 = gameboard[1][1];
        int z3 = gameboard[2][2];
        if (z1 == z2 && z2 == z3 && z1 != EMPTY){
            return z1;
        }
        int d1 = gameboard[0][0];
        int d2 = gameboard[1][1];
        int d3 = gameboard[2][2];
 
        if (d1 == d2 && d2 == d3 && d1 != EMPTY){
            return d1;
        }
        for(int row=0; row<gameboard.length; row++){
            for (int col=0; col<gameboard.length; col++){
                if(gameboard[row][col] == EMPTY)
                    return -2;
                }
        }
} return 0;
}
    public static void main(String[] args) {
        createBoard(3,3);
        int turn = 0;
        int playerVal;
        int outcome;
 
        java.util.Scanner scan = new java.util.Scanner(System.in);
 
        do {
            displayBoard();
            playerVal = (turn % 2 == 0)? NOUGHT : CROSS;
            if (playerVal == NOUGHT)
                System.out.println("O's turn");
            else{
                System.out.println("X's turn");
            }
            System.out.print("Enter row and column:");
 
            try {
                set(playerVal, scan.nextInt(), scan.nextInt());
            } catch (IllegalArgumentException ex)
            {System.err.println(ex);
            }
 
            turn ++;
            outcome=winOrTie();
        } while (-2 == outcome);
 
        displayBoard();
        switch(outcome) {
            case NOUGHT:
                System.out.println("O wins!");
                break;
            case CROSS:
                System.out.println("X wins!");
                break;
            case 0:
                System.out.println("Tie.");
                break;
 
        }
    }
 
static void set (int val, int row, int col) throws IllegalArgumentException {
    if (gameboard[row][col] == EMPTY) 
        gameboard[row][col] = val;
    else throw new 
        IllegalArgumentException("Player already there!");
}
 
static void displayBoard() {
        for (int row=0; row<gameboard.length; row++) {
            System.out.print("|");
                for (int col = 0; col<gameboard[row].length; col++) {                                         
                    switch (gameboard[row][col]) {
                        case NOUGHT:
                            System.out.print("O");
                            break;
                        case CROSS:
                            System.out.print("X");
                            break;
                        default:
                            System.out.print(" ");
                    }
                    System.out.print("|");
                    {
                        System.out.println("\n-------\n");
                    }
                }
            }
        }
 
   }

It's supposed to be a Tic-Tac-Toe game that displays a 3x3 gameboard. I'm using NetBeans to run it, and it's displaying each space on a separate line. Apparently there's a problem with the createBoard() method on line 19. It won't let me use the variable gameboard, but it won't let me use any other name either. Can someone give me some idea as to what I need to do to make this work?

Line 19 is the one that reads

int gameboard[][]= new int[row][col];

The error message I'm getting is

 
Exception in thread "main" java.lang.NullPointerException
	at tictactoegame.TicTacToeGame.displayBoard(TicTacToeGame.java:114)
	at tictactoegame.TicTacToeGame.main(TicTacToeGame.java:72)
C:\Users\owner\AppData\Local\NetBeans\Cache\8.2\executor-snippets\run.xml:53: Java returned: 1

I tried rewriting the line to read

gameboard= new int[row][col]

and that's when it runs but it displays nine individual spaces on nine individual lines instead of displaying a 3x3 square. Here's the complete code so you can see what I'm talking about.

public class TicTacToeGame {
 
    static int [][] gameboard;
    static final int EMPTY = 0;
    static final int NOUGHT = -1;
    static final int CROSS = 1;
    static void createBoard(int row, int col){
         gameboard= new int [row][col];
 
    }
 
static int winOrTie(){
        for (int r=0; r<gameboard.length; r++) {
            int x1=gameboard[r][0];
            int x2=gameboard[r][1];
            int x3=gameboard[r][2];
 
            if (x1 == x2 && x2 == x3 && x1 != EMPTY){
                return x1;
        }
        for (int c=0; c<gameboard.length; c++){
            int y1=gameboard[0][c];
            int y2=gameboard[1][c];
            int y3=gameboard[2][c];
 
            if (y1 == y2 && y2 == y3 && y1 != EMPTY){
                return y1;
            }
        }
 
        int z1 = gameboard[0][0];
        int z2 = gameboard[1][1];
        int z3 = gameboard[2][2];
        if (z1 == z2 && z2 == z3 && z1 != EMPTY){
            return z1;
        }
        int d1 = gameboard[0][0];
        int d2 = gameboard[1][1];
        int d3 = gameboard[2][2];
 
        if (d1 == d2 && d2 == d3 && d1 != EMPTY){
            return d1;
        }
        for(int row=0; row<gameboard.length; row++){
            for (int col=0; col<gameboard.length; col++){
                if(gameboard[row][col] == EMPTY)
                    return -2;
                }
        }
} return 0;
}
    public static void main(String[] args) {
        createBoard(3,3);
        int turn = 0;
        int playerVal;
        int outcome;
 
        java.util.Scanner scan = new java.util.Scanner(System.in);
 
        do {
            displayBoard();
            playerVal = (turn % 2 == 0)? NOUGHT : CROSS;
            if (playerVal == NOUGHT)
                System.out.println("O's turn");
            else{
                System.out.println("X's turn");
            }
            System.out.print("Enter row and column:");
 
            try {
                set(playerVal, scan.nextInt(), scan.nextInt());
            } catch (IllegalArgumentException ex)
            {System.err.println(ex);
            }
 
            turn ++;
            outcome=winOrTie();
        } while (-2 == outcome);
 
        displayBoard();
        switch(outcome) {
            case NOUGHT:
                System.out.println("O wins!");
                break;
            case CROSS:
                System.out.println("X wins!");
                break;
            case 0:
                System.out.println("Tie.");
                break;
 
        }
    }
 
static void set (int val, int row, int col) throws IllegalArgumentException {
    if (gameboard[row][col] == EMPTY) 
        gameboard[row][col] = val;
    else throw new 
        IllegalArgumentException("Player already there!");
}
 
static void displayBoard() {
        for (int row=0; row<gameboard.length; row++) {
            System.out.print("|");
                for (int col = 0; col<gameboard[row].length; col++) {                                         
                    switch (gameboard[row][col]) {
                        case NOUGHT:
                            System.out.print("O");
                            break;
                        case CROSS:
                            System.out.print("X");
                            break;
                        default:
                            System.out.print(" ");
                    }
                    System.out.print("|");
                    {
                        System.out.println("\n-------\n");
                    }
                }
            }
        }

Okay, this is what my output looks like:

run:
| |
-------
 
 |
-------
 
 |
-------
 
| |
-------
 
 |
-------
 
 |
-------
 
| |
-------
 
 |
-------
 
 |
-------
 
O's turn
Enter row and column:

I also noticed that there's a message that says that in gameboard.length, the field "length" references a null object. This is kind of what I thought the problem might be, but I have no idea how to correct it.

Thanks for your help, Norm. I finally got it.

public class TicTacToeGame {
 
    static int [][] gameboard;
    static final int EMPTY = 0;
    static final int NOUGHT = -1;
    static final int CROSS = 1;
    static void createBoard(int row, int col){
        gameboard = new int [row][col];
 
    } 
 
static int winOrTie(){
        for (int r=0; r<gameboard.length; r++) {
            int x1=gameboard[r][0];
            int x2=gameboard[r][1];
            int x3=gameboard[r][2];
 
            if (x1 == x2 && x2 == x3 && x1 != EMPTY){
                return x1;
        }
        for (int c=0; c<gameboard.length; c++){
            int y1=gameboard[0][c];
            int y2=gameboard[1][c];
            int y3=gameboard[2][c];
 
            if (y1 == y2 && y2 == y3 && y1 != EMPTY){
                return y1;
            }
        }
 
        int z1 = gameboard[0][0];
        int z2 = gameboard[1][1];
        int z3 = gameboard[2][2];
        if (z1 == z2 && z2 == z3 && z1 != EMPTY){
            return z1;
        }
        int d1 = gameboard[0][0];
        int d2 = gameboard[1][1];
        int d3 = gameboard[2][2];
 
        if (d1 == d2 && d2 == d3 && d1 != EMPTY){
            return d1;
        }
        for(int row=0; row<gameboard.length; row++){
            for (int col=0; col<gameboard.length; col++){
                if(gameboard[row][col] == EMPTY)
                    return -2;
                }
        }
} return 0;
}
    public static void main(String[] args) {
        createBoard(3,3);
        int turn = 0;
        int playerVal;
        int outcome;
 
        java.util.Scanner scan = new java.util.Scanner(System.in);
 
        do {
            displayBoard();
            playerVal = (turn % 2 == 0)? NOUGHT : CROSS;
            if (playerVal == NOUGHT)
                System.out.println("O's turn");
            else{
                System.out.println("X's turn");
            }
            System.out.print("Enter row and column:");
 
            try {
                set(playerVal, scan.nextInt(), scan.nextInt());
            } catch (IllegalArgumentException ex)
            {System.err.println(ex);
            }
 
            turn ++;
            outcome=winOrTie();
        } while (-2 == outcome);
 
        displayBoard();
        switch(outcome) {
            case NOUGHT:
                System.out.println("O wins!");
                break;
            case CROSS:
                System.out.println("X wins!");
                break;
            case 0:
                System.out.println("Tie.");
                break;
 
        }
    }
 
static void set (int val, int row, int col) throws IllegalArgumentException {
    if (gameboard[row][col] == EMPTY) 
        gameboard[row][col] = val;
    else throw new 
        IllegalArgumentException("Player already there!");
}
 
static void displayBoard() {
        for (int row=0; row<gameboard.length; row++) {
            System.out.print("|");
                for (int col = 0; col<gameboard[row].length; col++) {                    
                    switch (gameboard[row][col]) {
                        case NOUGHT:
                            System.out.print("O");
                            break;
                        case CROSS:
                            System.out.print("X");
                            break;
                        default:
                            System.out.print(" ");
                    }
                    System.out.print("|");
                }
 
 
                        System.out.println("\n-------\n");
 
                }
                }
        }

The output looks like this.

run:
| | | |
-------
 
| | | |
-------
 
| | | |
-------
 
O's turn
Enter row and column: