Lab5.1 (Java)

public class StudentList {
    private Student head;

    // Метод для добавления студента в список
    public void addStudent(Student newStudent) {
        newStudent.next = head;
        head = newStudent;
    }

    // Метод для добавления оценки студенту
    public void addMark(Student student, int subjectCode, int mark) {
        Marks newMark = new Marks(subjectCode, mark);
        newMark.next = student.marks;
        student.marks = newMark;
    }

    public void removeStudent(Student studentToRemove) {
        Student previousStudent = null;
        Student currentStudent = head;
        while (currentStudent != null && currentStudent != studentToRemove) {
            previousStudent = currentStudent;
            currentStudent = currentStudent.next;
        }

        if (currentStudent != null) {
            if (currentStudent.marks != null) {
                currentStudent.marks = null;
            }

            if (previousStudent != null) {
                previousStudent.next = currentStudent.next;
            } else {
                head = currentStudent.next;
            }
        }
    }

    public void printStudentsWithLowMarks() {
        Student currentStudent = head;
        if (currentStudent == null) {
            System.out.println("Список пуст! Добавьте запись");
            return;
        }
        boolean hasLowMarks = false;
        while (currentStudent != null) {
            Marks currentMark = currentStudent.marks;
            while (currentMark != null) {
                if (currentMark.mark < 4) {
                    hasLowMarks = true;
                    System.out.println("код группы: " + currentStudent.groupCode);
                    System.out.println("фамилия: " + currentStudent.lastName);
                    System.out.println("инициалы: " + currentStudent.initials);
                    System.out.println("----------------------------");
                    break;
                }
                currentMark = currentMark.next;
            }
            currentStudent = currentStudent.next;
        }
        if (!hasLowMarks) {
            System.out.println("Нет студентов с оценками ниже 4");
        }
    }

    public void printStudent() {
        Student currentStudent = head;
        if (currentStudent == null) {
            System.out.println("Список пуст!");
            return;
        }
        while (currentStudent != null) {
            String marks = "";
            Marks currentMarks = currentStudent.marks;
            while (currentMarks != null) {
                marks = marks + currentMarks.mark + " ";
                currentMarks = currentMarks.next;
            }
            System.out.print(currentStudent.groupCode + " ");
            System.out.print(currentStudent.lastName + " " + currentStudent.initials + " : ");
            System.out.println(marks);
            currentStudent = currentStudent.next;
        }
    }

    public int size() {
        int length = 0;
        Student currentStudent = head;
        while (currentStudent != null) {
            length++;
            currentStudent = currentStudent.next;
        }
        return length;
    }

    public Student getStudent(int num) {
        Student currentStudent = head;
        int i = 1;
        while (currentStudent != null && i != num) {
            i++;
            currentStudent = currentStudent.next;
        }
        return currentStudent;
    }

    public boolean checkRepeat(Student student) {
        Student currStudent = head;
        boolean isCorrect = true;
        while (currStudent != null) {
            if (currStudent == student) {
                isCorrect = false;
                System.out.println("Такая запись уже существует");
                break;
            }
            currStudent = currStudent.next;
        }
        return isCorrect;
    }

    public void replaceStudent(Student oldStudent, Student newStudent) { //int oldGroupCode, Student newStudent
        Student prevStudent = null;
        Student currentStudent = head;

        while (currentStudent != null && currentStudent != oldStudent) {
            prevStudent = currentStudent;
            currentStudent = currentStudent.next;
        }

        if (currentStudent != null) {
            if (prevStudent == null) {
                newStudent.next = head.next;
                head = newStudent;
            } else {
                newStudent.next = currentStudent.next;
                prevStudent.next = newStudent;
            }
        }
    }

    public Student getHead() {
        return head;
    }

}


public class Student {
    int groupCode;
    String lastName;
    String initials;
    Marks marks;
    Student next;

    Student(int groupCode, String lastName, String initials) {
        this.groupCode = groupCode;
        this.lastName = lastName;
        this.initials = initials;
        this.next = null;
    }

}

public class Marks {
    int subjectCode;
    int mark;
    Marks next;

    Marks(int subjectCode, int mark) {
        this.subjectCode = subjectCode;
        this.mark = mark;
        this.next = null;
    }
}


import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.util.*;

public class Main {
    static Scanner scanner = new Scanner(System.in);
    static StudentList studentList = new StudentList();

    public static void main(String[] args) throws IOException {
        System.out.println("Эта программа выводит студентов, у которых есть оценки ниже 4\n");
        int num = 0;
        do {
            getInfo();
            num = getNum();
            getUserChoice(num);
        } while (num != 0);
        scanner.close();
    }

    private static void getInfo() {
        System.out.println("""
                1 - Добавить студента в список\s
                2 - Редактировать список\s
                3 - Удалить студента из списка
                4 - Показать весь список\s
                5 - Сохранить список в файл\s
                6 - Загрузить данные из файла
                7 - Вывести информацию о студентах\s
                0 - Нажмите чтобы выйти""");
    }

    private static int getNum() {
        int MIN = 0;
        int MAX = 7;
        int choose = 0;
        boolean isCorrect;
        do {
            isCorrect = true;
            try {
                choose = Integer.parseInt(scanner.nextLine());
            } catch (Exception e) {
                isCorrect = false;
                System.out.println("Проверьте корректность данных");
            }
            if (isCorrect & (choose < MIN || choose > MAX)) {
                isCorrect = false;
            }
        } while (!isCorrect);
        return choose;
    }


    private static void addRecord() {
        int code;
        String lastName;
        String initial;
        boolean isCorrect = true;
        code = addCode();
        lastName = addLastName();
        initial = addInitial();
        int size = addSize();

        int[] mark = new int[size];
        mark = addMark(size);

        Student student = new Student(code, lastName, initial);
        for (int i = size - 1; i >= 0; i--) {
            studentList.addMark(student, code, mark[i]);
        }

        isCorrect = studentList.checkRepeat(student);
        if (isCorrect) {
            studentList.addStudent(student);
        }
    }

    private static int addCode() {
        int MIN = 251001;
        int MAX = 251005;
        int code = 0;
        boolean isCorrect;
        do{
            isCorrect = true;
            System.out.print("Введите код группы " + MIN + " - " + MAX + ": ");
            try {
                code = Integer.parseInt(scanner.nextLine());
            } catch (NumberFormatException e) {
                isCorrect = false;
                System.out.println("Проверьте корректность введенных данных");
            }
            if (isCorrect) {
                isCorrect = checkGroup(code);
            }
        } while (!isCorrect);
        return code;
    }

    private static boolean checkGroup(int num) {
        boolean isCorrect = false;
        int MIN = 251001;
        int MAX = 251005;
        if (num < MIN || num > MAX) {
            System.out.println("Ошибка номера введенной группы");
        } else {
            isCorrect = true;
        }
        return isCorrect;
    }

    private static String addLastName() {
        String name = "";
        boolean isCorrect;
        do {
            isCorrect = true;
            System.out.print("Введите фамилию студента: ");
            name = scanner.nextLine();
            isCorrect = checkName(name);
        } while (!isCorrect);
        return name;
    }

    private static boolean checkName(String name) {
        boolean isCorrect = false;
        int MIN = 2;
        int MAX = 15;
        if (name.length() < MIN || name.length() > MAX) {
            System.out.println("Вы вышли за пределы диапазона [2; 15]");
        } else {
            isCorrect = true;
        }
        return isCorrect;
    }

    private static String addInitial() {
        String init = "";
        boolean isCorrect;
        do {
            isCorrect = true;
            System.out.print("Введите инициалы студента: ");
            init = scanner.nextLine();
            isCorrect = checkInitial(init);
        } while (!isCorrect);
        return init;
    }

    private static boolean checkInitial(String initial) {
        boolean isCorrect = false;
        int MIN = 1;
        int MAX = 4;
        if (initial.length() < MIN || initial.length() > MAX) {
            System.out.println("Вы вышли за пределы диапазона [1; 4]");
        } else {
            isCorrect = true;
        }
        return isCorrect;
    }

    private static int[] addMark(int size) {
        boolean isCorrect;
        int[] mark = new int[size];
        for (int i = 0; i < size; i++) {
            do {
                isCorrect = true;
                System.out.println("Введите " + (i + 1) + " оценку");
                try {
                    mark[i] = Integer.parseInt(scanner.nextLine());
                } catch (Exception e) {
                    isCorrect = false;
                    System.out.println("Проверьте корректность данных");
                }
                if (isCorrect) {
                    isCorrect = checkMark(mark[i]);
                }
            } while (!isCorrect);
        }
        return mark;
    }

    public static boolean checkMark (int num) {
        boolean isCorrect = false;
        int MIN = 1;
        int MAX = 10;
        if (num < MIN || num > MAX) {
            System.out.println("Введите оценки от " + MIN + " до " + MAX);
        } else {
            isCorrect = true;
        }
        return isCorrect;
    }

    private static int addSize() {
        int num = 0;
        int MIN = 1;
        int MAX = 10;
        boolean isCorrect;
        do {
            isCorrect = true;
            System.out.println("Введите количество оценок у студента: ");
            try {
                num = Integer.parseInt(scanner.nextLine());
            } catch (Exception e) {
                isCorrect = false;
                System.out.println("");
            }
            if (isCorrect & (num < MIN || num > MAX)) {
                isCorrect = false;
                System.out.println("");
            }
        } while (!isCorrect);
        return num;
    }

    private static void deleteRecord() {
        if (studentList.size() == 0) {
            System.out.println("Список пуст! Добавьте запись");
            return;
        }
        Student student = getStudentOfRecord( "удалить");
        studentList.removeStudent(student);
    }

    private static Student getStudentOfRecord(String str) {
        int num = 0;
        final int MIN_NUM = 1;
        int length = studentList.size();
        boolean isIncorrect;
        do {
            isIncorrect = false;
            System.out.print("Введите номер записи которую хотите " + str + ": ");
            try {
                num = Integer.parseInt(scanner.nextLine());
            } catch (Exception q) {
                isIncorrect = true;
                System.out.println("Ошибка. Для ввода используйте цифры.");
            }
            if (!isIncorrect & (num < MIN_NUM || num > length)) {
                isIncorrect = true;
                System.out.println("Недопустимый диапазон входных данных.");
            }
        } while (isIncorrect);
        return studentList.getStudent(num);
    }

    private static void editRecord() {
        if (studentList.size() == 0) {
            System.out.println("Список пуст! Добавьте запись");
            return;
        }
        boolean isCorrect = true;
        Student student = getStudentOfRecord( "редактировать");
        int code = addCode();
        String lastName = addLastName();
        String initial = addInitial();
        int size = addSize();
        int[] mark = new int[size];
        mark = addMark(size);

        Student newStudent = new Student(code, lastName, initial);
        for (int i = size - 1; i >= 0; i--) {
            studentList.addMark(newStudent, code, mark[i]);
        }

        if (studentList.size() > 1) {
            isCorrect = studentList.checkRepeat(newStudent);
        }
        if (isCorrect) {
            studentList.replaceStudent(student, newStudent);
        }
    }


    private static String inputPath() {
        String path;
        boolean isCorrect;
        do {
            isCorrect = true;
            System.out.println("Введите полный путь к файлу");
            path = scanner.nextLine();
            File file = new File(path);
            if (!file.exists()) {
                isCorrect = false;
                System.out.println("Неверно введен путь");
            }
            if (!isCorrect && !file.canRead()) {
                System.out.println("Невозможно считать данные с файла");
            }
            if (!isCorrect && !file.canWrite()) {
                System.out.println("Невозможно записать данные в файл");
            }
        } while (!isCorrect);
        return path;
    }


    private static boolean checkDataCorrectness(String path) {
        boolean isCorrect = true;
        boolean isCorrectGroup, isCorrectName, isCorrectInitial, isCorrectMarks;
        String str;
        String[] mas;

        try {
            Scanner fileReader = new Scanner(new File(path));
            while((fileReader.hasNext()) & isCorrect) {
                str = fileReader.nextLine();
                mas = str.split(" ");
                if (mas.length < 4) {
                    System.out.println("Недостаточно данных в файле");
                    isCorrect = false;
                } else {
                    isCorrectGroup = checkGroup(Integer.parseInt(mas[0]));
                    isCorrectName = checkName(mas[1]);
                    isCorrectInitial = checkInitial(mas[2]);
                    isCorrectMarks = true;
                    int i = 3;
                    while (i < mas.length) {
                        isCorrectMarks = checkMark(Integer.parseInt(mas[i]));
                        i++;
                        if (!isCorrectMarks) {
                            break;
                        }
                    }

                    if (!isCorrectGroup || !isCorrectName || !isCorrectInitial || !isCorrectMarks) {
                        isCorrect = false;
                    }
                }
            }
        } catch (Exception q) {
            System.out.println("Проверьте корректность данных в файле.");
            isCorrect = false;
        }
        return isCorrect;
    }



    private static void openData() throws FileNotFoundException {
        String path = inputPath();
        boolean IsCorrect = checkDataCorrectness(path);
        if (IsCorrect) {
            System.out.println("Данные были успешно считаны.");
        } else {
            return;
        }
        String str;
        boolean isIncorrect = true;
        String[] mas;
        Scanner fileReader = new Scanner(new File(path));
        while((fileReader.hasNext())  & isIncorrect) {
            str = fileReader.nextLine();
            mas = str.split(" ");
            Student student = new Student(Integer.parseInt(mas[0]), mas[1],  mas[2]);
            int i = 3;
            while (i < mas.length) {
                studentList.addMark(student, Integer.parseInt(mas[0]), Integer.parseInt(mas[i]));
                i++;
            }
            isIncorrect = studentList.checkRepeat(student);

            if(isIncorrect) {
                studentList.addStudent(student);
            } else {
                System.out.println("Такая запись уже существует.");
            }
        }
    }

    private static void saveData(String path) throws IOException {
        if (studentList.size() == 0) {
            System.out.println("Список пуст!");
            return;
        }
        FileWriter writer = new FileWriter(path);
        Student currStudent = studentList.getHead();
        while (currStudent != null) {
            writer.write(currStudent.groupCode + " " + currStudent.lastName + " " + currStudent.initials + " ");
            Marks marks = currStudent.marks;
            while (marks != null) {
                writer.write(marks.mark + " ");
                marks = marks.next;
            }
            writer.write("\n");
            currStudent = currStudent.next;
        }
        writer.close();
    }

    private static void getUserChoice(int num) throws IOException {
        switch (num) {
            case 1 -> addRecord();
            case 2 -> editRecord();
            case 3 -> deleteRecord();
            case 4 -> studentList.printStudent();
            case 5 -> saveData(inputPath());
            case 6 -> openData();
            case 7 -> studentList.printStudentsWithLowMarks();
            case 0 -> System.exit(0);
        }
    }
}