laba_3_2_java

import java.io.*;
import java.util.Iterator;
import java.util.Scanner;
import java.util.HashSet;
import java.util.Set;

public class Lab2 {
    private static final Scanner scan = new Scanner(System.in);
    public static void main(String[] args) throws FileNotFoundException {
        String sequence;
        Set <Character> setOfSymbols;
        System.out.println("Given a non-empty sequence of characters, it is required to construct and print a set whose elements are signs of arithmetic operations and digits that occur in the sequence.");
        System.out.println("Type 1 - console input, type 0 - file input.");
        boolean chose = choose();
        if (chose)
            sequence = inputSequence();
        else {
            String path = inputFilePath();
            sequence = inputSequenceFromFile(path);
        }
        setOfSymbols = makeSet(sequence);
        System.out.println("Type 1 - console output, type 0 - file output.");
        chose = choose();
        if (chose)
            consoleOutput(setOfSymbols);
        else {
            fileOutput(setOfSymbols);
        }
    }
    private static String inputSequence() {
        String sequence;
        System.out.println("Input Sequence");
        sequence = scan.nextLine();
        return sequence;
    }

    private static String inputSequenceFromFile(String path) throws FileNotFoundException {
        String sequence;
        Scanner fileScanner;
        fileScanner = new Scanner(new File(path));
        sequence = fileScanner.nextLine();
        return sequence;
    }

    private static String inputFilePath() {
        String path;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            System.out.println("Input file path: ");
            path = scan.nextLine();
            File file = new File(path);
            if (!path.endsWith(".txt")) {
                System.out.println("File Extension error");
                isIncorrect = true;
            }
            if (!isIncorrect && !file.exists()) {
                System.out.println("Wrong way to file. Input correct path.");
                isIncorrect = true;
            }
        } while(isIncorrect);
        return path;
    }

    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(scan.nextLine());
            } catch (Exception e) {
                isIncorrect = true;
                System.out.println("Please, enter a integer number:");
            }
            if (inputNumber < MIN_NUM || inputNumber > MAX_NUM) {
                System.out.println("You are out of input range!:");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return inputNumber == 1;
    }
    private static Set<Character> makeSet(String sequence) {
        HashSet<Character> setOfSymbols = new HashSet<>();
        Set<Character> symbols = Set.of('/', '*', '-', '+', '%', '0', '1', '2', '3',
                '4', '5', '6', '7', '8', '9');
        for (char i : symbols)
        {
            if (sequence.contains(String.valueOf(i)))
                setOfSymbols.add(i);
        }
        return setOfSymbols;
    }

    private static void consoleOutput(Set<Character> setOfSymbols) {
        for (Character setOfSymbol : setOfSymbols)
            System.out.print(setOfSymbol + " ");
    }

    private static void fileOutput(Set <Character> setOfSymbols) {
        boolean isIncorrect;
        Iterator <Character> output = setOfSymbols.iterator();
        String path = inputFilePath();
        do {
            isIncorrect = false;
            try {
                FileWriter writer = new FileWriter(path);

                if (setOfSymbols.isEmpty())
                    writer.write("You have not entered any signs of arithmetic operations or digits.");
                else {
                    writer.write("The resulting set\n");
                    while (output.hasNext()) {
                        writer.write(output.next() + " ");
                    }
                }
                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.");
    }
}