The class in which we read the text file with the matrix and the number of generations:

import java.io.BufferedReader; import java.io.FileReader; import java.io.IOException; public class TextFileReader { private char[][] cells; private int width = 0; private int height = 0; private int generation; public void readFromFile(){ try(BufferedReader bufferedReader = new BufferedReader(new FileReader("D:\\life\\test.txt"))) { String value; while ((value = bufferedReader.readLine()) != null) { if (width == 0) { width = value.length(); } height++; } } catch (IOException e) { e.printStackTrace(); } cells = new char[height-1][width]; try(BufferedReader bufferedReader = new BufferedReader(new FileReader("D:\\life\\test.txt"))) { String currentLine; int row = 0; while (bufferedReader.ready()) { currentLine = bufferedReader.readLine(); if (row < (height-1)) { for (int i = 0; i < width; i++) { cells[row][i] = currentLine.charAt(i); } } else { generation = Integer.parseInt(currentLine); } row++; } } catch (IOException e) { e.printStackTrace(); } //========================= For Testing ===========================// System.out.println("Ширина: " + width + " Высота: " + (height-1)); for (int i = 0; i < height - 1; i++) { for (int j = 0; j < width; j++) System.out.print(cells[i][j] + " "); System.out.println(); } System.out.println("Количество поколений: " + generation); } public char[][] getCells() { return cells; } public char getCell(int row, int col) { return cells[row][col]; } public void setCells(char[][] cells) { this.cells = cells; } public int getGeneration() { return generation; } public int getHeight() { return height-1; } public int getWidth() { return width; } }

The class in which all the logic is executed:

 public class Cell { TextFileReader textFileReader = new TextFileReader(); private char[][] temporalCell; public void action () { textFileReader.readFromFile(); temporalCell = new char[textFileReader.getHeight()][textFileReader.getWidth()]; for (int i = 1; i < textFileReader.getGeneration(); i++) { for (int row = 0; row < textFileReader.getHeight(); row++) { for (int col = 0; col < textFileReader.getWidth(); col++) { int currentNeighbours = neighbours(row, col); if (currentNeighbours > 3 || currentNeighbours < 2) { temporalCell[row][col] = '.'; } else if (currentNeighbours == 3) { temporalCell[row][col] = 'o'; } else { temporalCell[row][col] = textFileReader.getCell(row, col); } } } textFileReader.setCells(temporalCell); } } public int neighbours (int row, int col) { int neighboursCount = 0; for (int i = row - 1; i <= row + 1; i++) { for (int j = col - 1; j <= col + 1; j++) { if (textFileReader.getCell(i, j) == ('o') && (i != row || j != col)) { neighboursCount++; } } } return neighboursCount; } }

The program throws an Exception in the neighbors () method, which is logical, because we go beyond the bounds of the matrix, because we do not have a method that defines the boundaries of the field. But that's not the point. How do I realize the surface of the torus, so that the left border is connected to the right, and the top - from the bottom? I reviewed many examples, but I could not understand how to implement it ((

    1 answer 1

    Use not the coordinates themselves, but the remainder of dividing them by the size of the field. That is, when passing through the neighboring cells, define their coordinates as textFileReader.getCell(i % textFileReader.getHeight(), j % textFileReader.getWidth()) . Thus, the coordinates will never exceed the dimensions of the matrix, and if they exceed, then the height (width) of the matrix will be automatically taken away from them, and they will go to its opposite side.

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      It should be clarified that the remainder of dividing a negative number by a positive using% yields a negative residue, which should be taken care of. - AlexeyM
    • fori1ton, thank you very much, I understood the essence) AlexeyM, I’m just thinking about it, in the Google calculator: (-1)% 4 = 3, and in Java = -1. But if we add a divisor to the dividend, everything seems to be obtained: (-1 + 4)% 4 = 3 - Ruslan Lozitsky