Laba2.2 java

package com.company;

import java.util.Scanner;
import java.io.*;

public class Main {
    public static Scanner scan = new Scanner(System.in);
    public final static String CHAR_MISTAKE_MESSAGE = "Error! Enter a number.\n";
    public final static String MISTAKE_NOT_FOUND_MESSAGE = "Error! File name can not be found. Please try again.";
    public final static String MISTAKE_NOT_OPEN_MESSAGE = "Error! Unable to open this file. Please check the file and try again.";

    public enum typeOfInput {
        CHOOSEKEYBOARD, CHOOSEFILE
    }

    public enum typeOfOutput {
        YES, NO
    }

    public static void main(String[] args) {
        final String THEME_MESSAGE = "This program finds pairs of friendly numbers in a given range.";
        final String DOTTED_LINE = "--------------------------------------------------------------------\n";
        int range = 0;
        int[] friendlyNumbers = new int[0];
        System.out.print(THEME_MESSAGE);
        System.out.print(DOTTED_LINE);
        typeOfInput Input = chooseInput();
        switch (Input) {
            case CHOOSEKEYBOARD:
                System.out.print("Please enter an upper limit (from 284 to 10,000) for the friendly number search range: ");
                range = checkInputNumber(284, 10000);
                break;
            case CHOOSEFILE:
                range = readRangeFromFile();
                System.out.println("Range: " + range);
                break;
        }
        friendlyNumbers = searchFriendlyNumber(range + 1);
        outputConsole(friendlyNumbers);
        typeOfOutput Output = chooseOutput();
        switch (Output) {
            case YES:
                writeToFile(friendlyNumbers);
                break;
            case NO:
                break;
        }
        System.out.print(DOTTED_LINE);
        System.out.println("Program completed");
    }

    public static int checkInputNumber(int min, int max) {
        boolean isCorrect = true;
        int number = 0;
        Scanner scan = new Scanner(System.in);
        do {
            try {
                number = scan.nextInt();
                if ((number > min - 1) && (number < max + 1)) {
                    isCorrect = false;
                } else {
                    System.out.println("Error! Enter a number. The number must be between " + min + " and " + max + "!");
                }
            } catch (Exception e){
                System.out.println("Error! The number must be between " + min + " and " + max + "!" );
                scan.next();
            }
        } while(isCorrect);
        isCorrect = true;
        return number;
    }

    public static void outputConsole(int[] array) {
        int lengthArray = array.length;
        int i = 0;
        System.out.println("Pair Friendship Numbers: ");
        while (i < lengthArray) {
            if (array[i] == 0){
                i = i + 2;
            }
            else {
                System.out.println(array[i] + " | " + array[i + 1] );
                i = i + 2;
            }
        }
    }

    public static int dividers(int number) {
        int sum = 1;
        for (int i = 2; i < number; i++)
            if (number % i == 0) {
                sum = sum + i;
            }
        return sum;
    }

    public static int[] searchFriendlyNumber(int range) {
        int[] array = new int[range];
        int a = 0;
        int[] friendlyNumbers = new int[10];
        for (int i = 1; i < range; i++) {
            int sumDividers = dividers(i);
            if (sumDividers < range && array[sumDividers] == i){
                friendlyNumbers[a] = sumDividers;
                a++;
                friendlyNumbers[a] = i;
                a++;
            }
            array[i] = sumDividers;
        }
        return friendlyNumbers;
    }

    public static typeOfInput chooseInput() {
        typeOfInput answer = null;
        boolean isNotCorrect;

        do {
            System.out.print("If you wish to fill in the matrix using the keyboard, please enter 'K', \nif you want to read an array from a file, please enter 'F': ");
            char symbol = scan.next().charAt(0);
            symbol = Character.toUpperCase(symbol);
            isNotCorrect = false;
            if ((symbol != 'K') & (symbol != 'F')) {
                System.out.println("Attention, an error occurred while input. Please try again.");
                isNotCorrect = true;
            }
            if (symbol == 'K') {
                answer = typeOfInput.CHOOSEKEYBOARD;
            } else if (symbol == 'F') {
                answer = typeOfInput.CHOOSEFILE;
            }
        }
        while (isNotCorrect);
        return answer;
    }

    public static int readRangeFromFile() {
        final String INPUT_MESSAGE = "Please enter a file name from which data will be read.\nFor example,\"C:\\Users\\Eugene\\Desktop\\Name.txt\".";
        boolean isInvalidInput;
        int range = 0;
        scan.nextLine();
        do {
            isInvalidInput = false;
            System.out.println(INPUT_MESSAGE);
            String fileName = scan.nextLine();
            try {
                BufferedReader input = new BufferedReader(new FileReader(fileName));
                String text = input.readLine();
                range = Integer.parseInt(text);
                if ((range < 283) || (range > 10001)) {
                    System.out.println("Error! The number in the file is not natural. Please check the file and try again.");
                    isInvalidInput = true;
                }
                input.close();
            } catch (FileNotFoundException e) {
                System.out.println(MISTAKE_NOT_FOUND_MESSAGE);
                isInvalidInput = true;
            } catch (IOException e) {
                System.out.println(MISTAKE_NOT_OPEN_MESSAGE);
                isInvalidInput = true;
            } catch (NumberFormatException e) {
                System.out.println("Error! The file contains invalid data. Please check the file and try again.");
                isInvalidInput = true;
            }
        } while (isInvalidInput);
        return range;
    }

    public static typeOfOutput chooseOutput() {
        typeOfOutput answer = null;
        boolean isNotCorrect;
        do {
            System.out.println("If you want to put the result in a file, please enter 'Y', \notherwise, please enter 'N':");
            char symbol = scan.next().charAt(0);
            symbol = Character.toUpperCase(symbol);
            isNotCorrect = false;
            if ((symbol != 'Y') & (symbol != 'N')) {
                System.out.println("Attention, an error occurred while entering. Please try again.");
                isNotCorrect = true;
            }
            if (symbol == 'Y') {
                answer = typeOfOutput.YES;
            } else if (symbol == 'N') {
                answer = typeOfOutput.NO;
            }
        }
        while (isNotCorrect);
        return answer;
    }

    public static void writeToFile(int[] friendlyNumbers) {
        final String OUTPUT_MESSAGE = "Please enter the name of the file in which you want to write the result.\nFor example, \"C:\\Users\\Eugene\\Desktop\\Answer.txt\".";
        boolean isInvalidOutput;
        int i = 0;
        int lengthArray = friendlyNumbers.length;
        scan.nextLine();
        do {
            isInvalidOutput = false;
            System.out.println(OUTPUT_MESSAGE);
            String FileName = scan.nextLine();
            try {
                BufferedWriter output = new BufferedWriter(new FileWriter(FileName));
                output.write("Pair Friendship Numbers: \n");
                while (i < lengthArray) {
                    if (friendlyNumbers[i] == 0){
                        i = i + 2;
                    }
                    else {
                        output.write(friendlyNumbers[i] + " | " + friendlyNumbers[i + 1] +  "\n" );
                        i = i + 2;
                    }
                }
                output.close();
            } catch (FileNotFoundException e) {
                System.out.println(MISTAKE_NOT_FOUND_MESSAGE);
                isInvalidOutput = true;
            } catch (IOException e) {
                System.out.println(MISTAKE_NOT_OPEN_MESSAGE);
                isInvalidOutput = true;
            }
        }
        while (isInvalidOutput);
        System.out.println("Data recording completed successfully.");
    }
}