laba3.2 (Java)

package com.company;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.lang.*;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws IOException {
        System.out.println("The program describes the set of vowels and consonants of the Russian language,\n" +
        " and determines the number of vowels and consonants in a sentence entered from the keyboard.");
        int source = chooseSource();
        String line = inputData(source);
        int numberOfVowels = calculateVowels(line);
        int numberOfConsonants = calculateConsonants(line);
        outputData(source, numberOfVowels, numberOfConsonants);
    }

    public static int chooseSource() {
        System.out.println("Choose where to enter data. Enter 1 or 2:\n 1.File\n 2.Console");
        Scanner scan = new Scanner(System.in);
        int choice = 0;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            try {
                choice = Integer.parseInt(scan.nextLine());
            }catch (Exception e){
                System.out.println("Enter an integer!");
                isIncorrect = true;
            }
            if (!isIncorrect && choice != 1 && choice != 2){
                System.out.println("Enter 1 or 2!");
                isIncorrect = true;
            }
        }while (isIncorrect);
        return choice;
    }

    public static String inputData(int source) throws FileNotFoundException {
        String line = "";
        switch (source){
            case 1:
                System.out.println("Enter the absolute link to the input file");
                String pathInput = inputPath();
                line = inputLineFromFile(pathInput);
                break;
            case 2:
                line = inputLineFromConsole();
                break;
        }
        return line;
    }

    public static String inputPath() {
        Scanner scan = new Scanner(System.in);
        boolean isIncorrect;
        String path;
        do {
            isIncorrect = false;
            path = scan.nextLine();
            File file = new File(path);

            if (!file.exists()){
                System.out.println("File not found!\nEnter the absolute link to the file");
                isIncorrect = true;
            }
        }while (isIncorrect);
        System.out.println();
        return path;
    }

    public static String inputLineFromFile(String path) throws FileNotFoundException {
        File inputFile = new File(path);
        Scanner scan = new Scanner(inputFile);
        String line;
        if (inputFile.length() != 0){
            line = scan.nextLine();
        }else{
            System.out.println("The line is missing from your file!\nEnter it from console ");
            line = inputLineFromConsole();
        }
        return line;
    }

    public static String inputLineFromConsole() {
        Scanner scan = new Scanner(System.in);
        boolean isIncorrect;
        String line;
        System.out.println("Enter the line");
        do {
            isIncorrect = false;
            line = scan.nextLine();
            if (line.length() == 0){
                System.out.println("You entered an empty line!\nRepeat enter");
                isIncorrect = true;
            }
        }while (isIncorrect);
        return line;
    }

    public static int calculateVowels(String line){
        HashSet<Character> vowelsLetters = new HashSet<>(Arrays.asList('а','о','у','ы','э','я','ё','ю','и','е'));
        int amount = 0;
        for (int i = 0; i < line.length(); i++){
            if (vowelsLetters.contains(Character.toLowerCase(line.charAt(i)))) {
                amount++;
            }
        }
        return amount;
    }

    public static int calculateConsonants(String line){
        HashSet<Character> consonantsLetters = new HashSet<>(Arrays.asList('б','в','г','д','ж','з','й','к','л','м','н','п','р','с','т','ф','х','ц','ч','ш','щ'));
        int amount = 0;
        for (int i = 0; i < line.length(); i++){
            if (consonantsLetters.contains(Character.toLowerCase(line.charAt(i)))) {
                amount++;
            }
        }
        return amount;
    }

    public static void outputData(int source, int numberOfVowels, int numberOfConsonants ) throws IOException {
        if (source == 1) {
            System.out.println("\nEnter the absolute link to the output file");
            String pathOutput = inputPath();
            outputToFile(pathOutput, numberOfVowels, numberOfConsonants);
        }else {
            outputToConsole(numberOfVowels, numberOfConsonants);
        }
    }

    public static void outputToFile(String path, int numberOfVowels, int numberOfConsonants) throws IOException {
        FileWriter writer = new FileWriter(path);
        writer.write("Vowels: " + numberOfVowels + "\nConsonants: " + numberOfConsonants);
        writer.close();
        System.out.println("The data is successfully recorded in the file");
    }

    public static void outputToConsole(int numberOfVowels, int numberOfConsonants){
        System.out.println("\nVowels: " + numberOfVowels + "\nConsonants: " + numberOfConsonants);
    }
}