BoardUtils.java

public class BoardUtils {

    public static void printBoard(int[][] board) {
        System.out.println("   0 1 2   3 4 5   6 7 8");
        for (int i = 0; i < 9; i++) {
            if (i % 3 == 0)
                System.out.println("  +-------+-------+-------+");
            System.out.print(i + " | ");
            for (int j = 0; j < 9; j++) {
                if (board[i][j] == 0)
                    System.out.print(". ");
                else
                    System.out.print(board[i][j] + " ");
                if ((j + 1) % 3 == 0)
                    System.out.print("| ");
            }
            System.out.println();
        }
        System.out.println("  +-------+-------+-------+");
    }

    public static boolean isBoardFull(int[][] board) {
        for (int[] row : board)
            for (int cell : row)
                if (cell == 0)
                    return false;
        return true;
    }

    public static int[][] deepCopy(int[][] original) {
        int[][] copy = new int[original.length][original[0].length];
        for (int i = 0; i < original.length; i++) {
            System.arraycopy(original[i], 0, copy[i], 0, original[0].length);
        }
        return copy;
    }
}