如何使X和O交替

Question

I am trying to make the X's and O's alternate after each turn like in a normal tic tac toe game, but when I run it, all that happens is that it keeps outputting X after each turn. Why is this happening?

import java.util.Scanner;
public class TicTacToe{
    public static void main(String[] args){
        Scanner reader = new Scanner(System.in);
        Scanner numreader = new Scanner(System.in);

        TicTacToeBoard board = new TicTacToeBoard(620,720);
        board.setFiles("X.png", "O.jpeg");
        int[][] lines = new int[4][4];

        lines[0][0] = 0;
        lines[0][1] = 200;
        lines[0][2] = 600;
        lines[0][3] = 200;

        lines[1][0] = 0;
        lines[1][1] = 400;
        lines[1][2] = 800;
        lines[1][3] = 400;

        lines[2][0] = 200;
        lines[2][1] = 600;
        lines[2][2] = 200;
        lines[2][3] = 0;

        lines[3][0] = 400;
        lines[3][1] = 600;
        lines[3][2] = 400;
        lines[3][3] = 0;
        board.defineBoard(lines);
        int counter = 0;

        char[][] arr= {
                        {'-','-','-'},
                        {'-','-','-'},
                        {'-','-','-'},
                    };
        board.setBoard(arr);
        int a = 0;


        for(int i = 0; i<9; i++){

        System.out.println("Enter what row:");
        int y = numreader.nextInt();

        System.out.println("Enter what column:");
        int z = numreader.nextInt();

        if(arr[y][z]=='-'){
            arr[y][z]='x';
            board.setBoard(arr);
            board.repaint();
            counter ++;}
        else
            System.out.println("This is not allowed");
        }
    }
}

Answer 1

Your code seems to explicitly set the tile to x .

arr[y][z]='x';

I suspect you'll want something like

arr[y][z]= counter % 2 == 0 ? 'x' : 'o';

Also, watch out. You will iterate 9 times on your "input a row/column" code, no matter if the input is valid. This means that if you input an invalid row/column combination, you'll end up with an 8 turn game.

Answer 2

You always change with 'x':

arr[y][z]='x'

You could do this:

if(arr[y][z]=='-'){
   if (counter % 2 == 0) arr[y][z]='x';
   else arr[y][z]='o';

   board.setBoard(arr);
   board.repaint();
   counter ++;
}

When counter is even, you change to 'x'. And when is odd, you change to 'o'.

Answer 3

Try implementing something like the following instead of your arr[y][z]='x'; line :

if (counter % 2 == 0)
  arr[y][z]='x';
else
  arr[y][z]='o';

So it would alternate based on the counter value (ie if counter is even, then it's 'x's turn, else it's 'o')

I hope that helps

Answer 4

Because you are always setting it to 'x' here: arr[y][z]='x'; . You need to have a condition where you alternate this value to 'x' and 'o'. Something like a flag which you set and reset on each iteration to determine if you want 'x' or 'o'.