Как сделать список из DataFrame RMD

Я создал следующий 2D-массив из предоставленного вами файла:

 37 | 48 | 59 | 70 | 81 |  2 | 13 | 24 | 35
----+----+----+----+----+----+----+----+----
 36 | 38 | 49 | 60 | 71 | 73 |  3 | 14 | 25
----+----+----+----+----+----+----+----+----
 26 | 28 | 39 | 50 | 61 | 72 | 74 |  4 | 15
----+----+----+----+----+----+----+----+----
 16 | 27 | 29 | 40 | 51 | 62 | 64 | 75 |  5
----+----+----+----+----+----+----+----+----
  6 | 17 | 19 | 30 | 41 | 52 | 63 | 65 | 76
----+----+----+----+----+----+----+----+----
 77 |  7 | 18 | 20 | 31 | 42 | 53 | 55 | 66
----+----+----+----+----+----+----+----+----
 67 | 78 |  8 | 10 | 21 | 32 | 43 | 54 | 56
----+----+----+----+----+----+----+----+----
 57 | 68 | 79 |  9 | 11 | 22 | 33 | 44 | 46
----+----+----+----+----+----+----+----+----
 47 | 58 | 69 | 80 |  1 | 12 | 23 | 34 | 45

Массив определяет размер квадрата, когда он читает первую строку файла. Это очень динамично. Его работы до тех пор, пока входной файл является идеальным квадратом. У меня нет дополнительной обработки ошибок.

Вот простой подход, который должен придерживаться ваших рекомендаций.

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ReadMagicSquare {
    public static int[][] create2DIntMatrixFromFile(String filename) throws Exception {
        int[][] matrix = null;

        // If included in an Eclipse project.
        InputStream stream = ClassLoader.getSystemResourceAsStream(filename);
        BufferedReader buffer = new BufferedReader(new InputStreamReader(stream));

        // If in the same directory - Probably in your case...
        // Just comment out the 2 lines above this and uncomment the line
        // that follows.
        //BufferedReader buffer = new BufferedReader(new FileReader(filename));

        String line;
        int row = 0;
        int size = 0;

        while ((line = buffer.readLine()) != null) {
            String[] vals = line.trim().split("\\s+");

            // Lazy instantiation.
            if (matrix == null) {
                size = vals.length;
                matrix = new int[size][size];
            }

            for (int col = 0; col < size; col++) {
                matrix[row][col] = Integer.parseInt(vals[col]);
            }

            row++;
        }

        return matrix;
    }

    public static void printMatrix(int[][] matrix) {
        String str = "";
        int size = matrix.length;

        if (matrix != null) {
            for (int row = 0; row < size; row++) {
                str += " ";
                for (int col = 0; col < size; col++) {
                    str += String.format("%2d",  matrix[row][col]);
                    if (col < size - 1) {
                        str += " | ";
                    }
                }
                if (row < size - 1) {
                    str += "\n";
                    for (int col = 0; col < size; col++) {
                        for (int i = 0; i < 4; i++) {
                            str += "-";
                        }
                        if (col < size - 1) {
                            str += "+";
                        }
                    }
                    str += "\n";
                } else {
                    str += "\n";
                }
            }
        }

        System.out.println(str);
    }

    public static void main(String[] args) {
        int[][] matrix = null;

        try {
            matrix = create2DIntMatrixFromFile("square.txt");
        } catch (Exception e) {
            e.printStackTrace();
        }

        printMatrix(matrix);
    }
}

Этот подход более совершенен и оптимизирован.

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class ReadMagicSquare {

    private int[][] matrix;
    private int size = -1;
    private int log10 = 0;
    private String numberFormat;

    public ReadMagicSquare(String filename) {
        try {
            readFile(filename);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void readFile(String filename) throws IOException {
        // If included in an Eclipse project.
        InputStream stream = ClassLoader.getSystemResourceAsStream(filename);
        BufferedReader buffer = new BufferedReader(new InputStreamReader(stream));

        // If in the same directory - Probably in your case...
        // Just comment out the 2 lines above this and uncomment the line
        // that follows.
        //BufferedReader buffer = new BufferedReader(new FileReader(filename));

        String line;
        int row = 0;

        while ((line = buffer.readLine()) != null) {
            String[] vals = line.trim().split("\\s+");

            // Lazy instantiation.
            if (matrix == null) {
                size = vals.length;
                matrix = new int[size][size];
                log10 = (int) Math.floor(Math.log10(size * size)) + 1;
                numberFormat = String.format("%%%dd", log10);
            }

            for (int col = 0; col < size; col++) {
                matrix[row][col] = Integer.parseInt(vals[col]);
            }

            row++;
        }
    }

    @Override
    public String toString() {
        StringBuffer buff = new StringBuffer();

        if (matrix != null) {
            for (int row = 0; row < size; row++) {
                buff.append(" ");
                for (int col = 0; col < size; col++) {
                    buff.append(String.format(numberFormat,  matrix[row][col]));
                    if (col < size - 1) {
                        buff.append(" | ");
                    }
                }
                if (row < size - 1) {
                    buff.append("\n");
                    for (int col = 0; col < size; col++) {
                        for (int i = 0; i <= log10 + 1; i++) {
                            buff.append("-");
                        }
                        if (col < size - 1) {
                            buff.append("+");
                        }
                    }
                    buff.append("\n");
                } else {
                    buff.append("\n");
                }
            }
        }

        return buff.toString();
    }

    public static void main(String[] args) {
        ReadMagicSquare square = new ReadMagicSquare("square.txt");
        System.out.println(square.toString());
    }
}