How can I print a 1D array to be 3 x 3 and how can I have an RNG computer check values and to keep searching for an empty space?

I have been working on a 1D Tic Tac Toe project for a while now, and I am still fairly new to coding, so I have a couple questions/issues.

• To start off, I am having issues with printing the board as a 1D String array. Primarily setting it up in the three x three fashion with the 'blanks' represented as '-'.

  //global variables
  
  static int ArrayLength = 9;
  
  static String[] board = new String[ArrayLength];
  
  static int maxVal = ArrayLength;
  
  
  static void PrntBoard() 
  
  {
      for (int cntr = '-'; cntr < maxVal; cntr++) 
  {
  
   System.out.println(board[cntr]);
  
  
         }
  }
  
  

• I am also experiencing issues with my Computer Moves, as I keep getting errors with the computer unable to wrap around the array to eventually find an empty space and checking if a space is available in the first place.

  static void CompMove() {

  int space = 0;
  
  //keep asking till they get an empty one
  
      //have the comp random pick a spot
      space = RNG.nextInt(9);
      //check
      while (board[space].equals('X') || board[space].equals('O'));
      {
          space = RNG.nextInt(9)-1;
  
      }
  
  
  
  //fill in the game board with the valid position
  if (board[space].equals('-')) {
      board[space].equals('O');
      PrntBoard();
  }
  int lastspace = space;
  
  }
  
  

Any help would be greatly appreciated, as I am still, quite frankly, a novice and do not possess much knowledge in coding. Thank you.