4.4 java

import java.util.Scanner;
import java.io.*;
public class Permutations {
    private static final Scanner scanner = new Scanner(System.in);
    static Scanner fileScanner;
    static int num = 1; // номер перестановки

    public static void main (String[] args) {
        int num;
        int[] arr;
        System.out.println("the program generates all permutations of n elements in lexicographic order.");
        System.out.println("Enter type of input." + '\n' + "1 is console input, 0 is file input.");
        String path;
        boolean chose = choose();
        if (chose) {
            System.out.println("Input size of plurality:");
            num = inputArraySize();
            System.out.println("Input plurality elements:");
            arr = inputArray(num);
        } else {
            path = inputFilePath();
            num = inputSizeOfArrayFromFile(path);
            arr = inputArrayFile(path, num);
        }
        output(num, arr);
    }

    private static boolean choose() {
        int inputNumber = 0;
        boolean isIncorrect;
        final int MIN_NUM = 0;
        final int MAX_NUM = 1;
        do {
            isIncorrect = false;
            try {
                inputNumber = Integer.parseInt(scanner.nextLine());
            } catch (Exception e) {
                isIncorrect = true;
                System.out.println("Please, enter a number.");
            }
            if (!isIncorrect && (inputNumber < MIN_NUM || inputNumber > MAX_NUM)) {
                System.out.println("You are out of input range!");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return inputNumber == 1;
    }

    private 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 integer number:");
            }
        } while (isIncorrect);
        return n;
    }

    private static int inputArraySize() {
        boolean isIncorrect;
        final int MIN_SIZE = 2;
        final int MAX_SIZE = 7;
        int num;
        do {
            num = inputData();
            isIncorrect = false;
            if ((num < MIN_SIZE) || (num > MAX_SIZE)) {
                System.out.println("Array size should be in the range from 2 to 7:");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return num;
    }

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

    private 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;
    }
    private static int inputSizeOfArrayFromFile(String path) {
        int num = 0;
        boolean isIncorrect;
        final int MIN = 1;
        final int MAX = 7;
        do {
            isIncorrect = false;
            try {
                fileScanner = new Scanner(new File(path));
                num = fileScanner.nextInt();
            } catch (Exception q) {
                isIncorrect = true;
                System.out.println("Check file.");
                path = inputFilePath();
            }
            if (!isIncorrect && ((num < MIN) || (num > MAX))) {
                isIncorrect = true;
                System.out.println("Array size should be in the range from 2 to 7:");
                path = inputFilePath();
            }
        } while (isIncorrect);
        return num;
    }

    private static int[] inputArrayFile(String path, int num) {
        boolean isIncorrect;
        int[] arr = new int[num];
        do {
            isIncorrect = false;
            try {
                fileScanner = new Scanner(new File(path));
                fileScanner.nextLine();
                for (int i = 0; (i < arr.length); i++) {
                    arr[i] = fileScanner.nextInt();
                }
            } catch (Exception q) {
                isIncorrect = true;
                System.out.println("Reading of array elements failed.");
                path = inputFilePath();
            }
        } while (isIncorrect);
        return arr;
    }

    public static void swap(int[] arr, int i, int j)
    {
        int temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
    }

    public static boolean nextSet(int[] arr, int n)
    {
        int j = n - 2;
        while (j != -1 && arr[j] >= arr[j + 1])
            j--;
        if (j == -1)
            return false; //закончились
        int k = n - 1;
        while (arr[j] >= arr[k])
            k--;
        swap(arr, j, k);
        int l = j + 1;
        int r = n - 1;
        while (l < r)
            swap(arr, l++, r--);
        return true;
    }

    public static void print (int[] arr, int n)
    {
        System.out.print((num++) + ": ");
        for (int i = 0; i < n; i++)
            System.out.print(arr[i] + " ");
        System.out.println();
    }

    public static void output (int num, int[] arr) {
        System.out.println(num + " elements:");
        print(arr, num);
        while (nextSet(arr, num))
            print(arr, num);
    }

}