lab3_2_0

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

public class lab3_2 {

    static Scanner scConsole = new Scanner(System.in);

    private static PrintWriter getOutputFileLocation() {
        boolean isIncorrect;
        String location;
        PrintWriter file = null;
        do {
            isIncorrect = false;
            System.out.println("Enter file location:");
            location = scConsole.nextLine();
            try {
                file = new PrintWriter(location);
            } catch (FileNotFoundException e) {
                isIncorrect = true;
                System.out.println("File with this location is not found");
            }
        } while (isIncorrect);
        if (file != null)
            System.out.println("File opened successfully");
        return file;
    }

    private static Scanner getInputFileLocation() {
        boolean isIncorrect;
        String location;
        Scanner file = null;
        do {
            isIncorrect = false;
            System.out.println("Enter file location:");
            location = scConsole.nextLine();
            try {
                file = new Scanner(new File(location));
            } catch (FileNotFoundException e) {
                isIncorrect = true;
                System.out.println("File with this location is not found");
            }
        } while (isIncorrect);
        if (file != null)
            System.out.println("File opened successfully");
        return file;
    }

    public static String getLineFromFile() {
        String str = null;
        Scanner file = getInputFileLocation();
        boolean isIncorrect = false;
        do {
            try {
                str = file.nextLine();
            } catch (Exception e) {
                isIncorrect = true;
                System.out.println("Enter natural number");
            }
            if ((!isIncorrect) && (str.length() == 0)) {
                System.out.println("The line is empty");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return str;
    }


    private static String getLineFromConsole () {
        String str = null;
        boolean isIncorrect;
        do {
            isIncorrect = false;
            try {
                str = scConsole.nextLine();
            } catch (Exception e) {
                System.out.println("Enter the number");
                isIncorrect = true;
            }
            if (str.length() == 0) {
                System.out.println("You entered an empty line!\nRepeat enter");
                isIncorrect = true;
            }
        } while (isIncorrect);
        return str;
    }


    private static String changeSentence(String str){
        HashSet<Character> LetSet = new HashSet<>();
        boolean isNotUnique;
        int i = 0;
        int temp = str.length();
        while (i < temp){
            isNotUnique = CheckUnique(str, i, LetSet);
            if (isNotUnique){
                StringBuilder sb = new StringBuilder(str);
                sb.delete(i,i+1);
                str = sb.toString();
                temp--;
            }else {
                LetSet.add(str.charAt(i));
                i++;
            }
        }
        return str;
    }

    private static boolean CheckUnique(String str, int i, HashSet LetSet){
        boolean isNotUnique;
        isNotUnique = LetSet.contains(str.charAt(i));
        return isNotUnique;
    }


    private static void outputToFile(String str) {
        PrintWriter out = getOutputFileLocation();
        out.print(str);
        out.close();
    }

    private static int chooseInput () {
        boolean isIncorrect;
        String line;
        do {
            isIncorrect = false;
            System.out.println("Do you want to input from file? (y/n)");
            line = scConsole.nextLine().toLowerCase();
            if (!line.equals("y") && !line.equals("n") && !line.equals("")) {
                isIncorrect = true;
                System.out.println("Enter valid answer");
            }
        } while (isIncorrect);
        if (line.equals("y") || line.equals("")) {
            return 0;
        } else {
            return 1;
        }
    }

    public static void main (String[]args){
        String str;
        System.out.println("Данная программа удаляет одинаковые элементы строки , оставляя один экземпляр символа.");
        int chosenInput = chooseInput();
        System.out.println("Enter the string");
        if (chosenInput == 0) {
            str = getLineFromFile();
        } else {
            str = getLineFromConsole();
        }
        str = changeSentence(str);
        System.out.println("Modified string:");
        System.out.println(str);
        outputToFile(str);
    }
}