private boolean isTie() {
        Player[][] locations = this.board.getBoardLocations();

        for (int row = 0; row < locations.length; row++) {
            Player[] rowLocations = locations[row];
            for (int col = 0; col < rowLocations.length; col++) {
                Player location = rowLocations[col];
                if (locations[row][col] == null) { 
                    return false;
                }
            }
        }

        return true;
    }