laba_2_4_java

import java.util.Scanner;
import java.io.*;
public class moveMatrix {
    private static final Scanner scanner = new Scanner(System.in);
    private static Scanner fileScanner;

    public static void main(String[] args) {
        int n;
        int[][] arr;
        System.out.println("Enter 1 or 0. " + '\n' + "1 is console input, 0 is file input.");
        int chose = choose();
        if (chose == 1) {
            System.out.println("Input matrix size: ");
            n = inputArraySize();
            System.out.println("Enter the numbers one by one: ");
            arr = inputArray(n);
        } else {
            String str = inputFilePath();
            n = inputSizeOfMatrixFromFile(str);
            arr = inputMatrixFile(str,n);
        }
        int starti = 0;
        int startj = starti;
        int[] bufferFor1 = transferMatrixVector(n, arr, starti, startj);

        starti = 0;
        startj = n / 2;
        int[] bufferFor2 = transferMatrixVector(n, arr, starti, startj);

        starti = n / 2;
        startj = 0;
        int[] bufferFor3 = transferMatrixVector(n, arr, starti, startj);

        starti = n / 2;
        startj = starti;
        int[] bufferFor4 = transferMatrixVector(n, arr, starti, startj);

        int i;
        int j;
        int k = 0;
        for (i = 0; i < n; i++) {
            for (j = 0; j < n; j++) {
                if ((i < n / 2) && (j < n / 2))
                    arr[i][j] = bufferFor4[k];
                k = 0;
                if ((i < n / 2) && (j > n / 2 - 1))
                    arr[i][j] = bufferFor3[k];
                if ((i > n / 2 - 1) && (j < n / 2))
                    arr[i][j] = bufferFor1[k];
                if ((i > n / 2 - 1) && (j > n / 2 - 1))
                    arr[i][j] = bufferFor2[k];
                k++;
            }
        }
        System.out.println("Enter 1 or 0.");
        System.out.println("1 is console output, 0 is file output.");
        chose = choose();
        if (chose == 1)
            outputArray(n, arr);
        else {
            String str = inputFilePath();
            fileOutput(arr, n, str);
        }
        scanner.close();
        fileScanner.close();
    }


    public static int choose() {
        int chose = 0;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            try {
                chose = Integer.parseInt(scanner.nextLine());
            } catch (Exception e) {
                isIncorrect = true;
                System.out.println("Please, enter a positive integer number:");
            }
            if ((isIncorrect) || !((chose == 1) || (chose == 0))) {
                isIncorrect = true;
                System.out.println("Please, choose.");
                System.out.println("1 is console input/output, 0 is file input/output.");
            }
        } while (isIncorrect);
        return chose;
    }
    // консольный ввод и вывод. Функции для них
    public static int inputData() {
        int n = 0;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            try {
                n = Integer.parseInt(scanner.nextLine());
            } catch (Exception e) {
                isIncorrect = true;
                System.out.println("Please, enter a positive integer number:");
            }
        } while (isIncorrect);
        return n;
    }

    public static int inputPositiveNumber () {
        int npos;
        final int MIN = 1;
        boolean isIncorrect;
        do {
            npos = inputData();
            isIncorrect = false;
            if (npos < MIN) {
                System.out.println("Please, enter a positive number.");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return npos;
    }

    public static int inputArraySize() {
        boolean isIncorrect;
        int num;
        do {
            num = inputPositiveNumber();
            isIncorrect = false;
            if (num % 2 != 0) {
                System.out.println("Please, enter an even number:");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return num;
    }

    public static int[][] inputArray(int num) {
        int i;
        int j;
        int[][] arr = new int[num][num];
        for (i = 0; i < num; i++)
            for (j = 0; j < num; j++)
                arr[i][j] = inputData();
        return arr;
    }

    public static int[] transferMatrixVector(int n, int[][] arr, int starti, int startj) {
        final int min = 4;
        int[] quarter = new int[(n * n) / min];
        int k = 0;
        int i;
        int j;
        int halfn = n / 2;
        for (i = starti; i < starti + halfn; i++) {
            for (j = startj; j < startj + halfn; j++) {
                quarter[k] = arr[i][j];
                k++;
            }
        }
        return quarter;
    }





    public static void outputArray(int num, int[][] arr) {
        int i;
        int j;
        for (i = 0; i < num; i++) {
            for (j = 0; j < num; j++)
                System.out.print(arr[i][j] + " ");
            System.out.print('\n');
        }
    }
    //functions for files:
    public static String inputFilePath() {
        String path;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            System.out.println("Input file path:");
            path = scanner.nextLine();
            File file = new File(path);
            if (!file.exists()) {
                System.out.println("Wrong way to file.");
                isIncorrect = true;
            }
            if (!file.canRead() && file.exists()) {
                System.out.println("Impossible to read a file.");
                isIncorrect = true;
            }
            if (!file.canWrite() && file.canRead()) {
                System.out.println("Impossible to write a file.");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return path;
    }

    public static int inputSizeOfMatrixFromFile(String path) {
        int n = 0;
        boolean isIncorrect;
        final int MIN = 1;
        final int MAX = 10;
        do {
            isIncorrect = false;
            try {
                fileScanner = new Scanner(new File(path));
                n = fileScanner.nextInt();
            } catch (Exception q) {
                isIncorrect = true;
                System.out.println("Check file");
                path = inputFilePath();
            }
            if (!isIncorrect && (n < MIN || n > MAX)) {
                isIncorrect = true;
                System.out.println("Matrix size should be at least 2");
            }
        } while (isIncorrect);
        return n;
    }
    public static int[][] inputMatrixFile(String path, int num) {
        boolean isIncorrect;
        int i, j;
        int[][] arrFile = new int[num][num];
        for (i = 0; i < num; i++)
            arrFile[i] = new int[num];
        do {
            isIncorrect = false;
            try {
                fileScanner = new Scanner(new File(path));
                fileScanner.nextLine();
                for (i = 0; (i < num); i++) {
                    for (j = 0; (j < num); j++) {
                        arrFile[i][j] = Integer.parseInt(fileScanner.next());
                    }
                }
            } catch (Exception q) {
                isIncorrect = true;
                System.out.println("Reading of matrix elements failed.");
                path = inputFilePath();
            }
        } while (isIncorrect);
        return arrFile;
    }
    private static void fileOutput(int[][] arr, int num, String path) {
        boolean isIncorrect;
        do {
            isIncorrect = false;
            try {
                FileWriter writer = new FileWriter(path);
                for (int i = 0; i < num; i++){
                    for (int j = 0; j < num; j++) {
                        writer.write((arr[i][j]) + " ");
                    }
                    writer.write('\n');
                }
                writer.close();
            } catch (IOException e) {
                isIncorrect = true;
                System.out.println("Mistake of output in file. Input path.");
                path = inputFilePath();
            }
        } while(isIncorrect);
        System.out.println("Successful output in file.");
    }
}