java设计一个学生信息管理系统，能够实现学生信息（学号、姓名、性别、民族、年龄、年级、班级、专 业、电话、E-mail）的增加、删除、修改、查询以及更新功能。要将学生信息及其变动情况存储在 out.txt中。

好的，这是一个比较典型的 Java 项目，需要设计类、接口和文件存储等功能。下面是一个简单的实现方案：

1. 学生信息类：Student

public class Student {
    private String id; // 学号
    private String name; // 姓名
    private String gender; // 性别
    private String nation; // 民族
    private int age; // 年龄
    private int grade; // 年级
    private int clazz; // 班级
    private String major; // 专业
    private String phone; // 电话
    private String email; // 邮箱

    // 构造方法
    public Student(String id, String name, String gender, String nation, int age, int grade, int clazz, String major, String phone, String email) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.nation = nation;
        this.age = age;
        this.grade = grade;
        this.clazz = clazz;
        this.major = major;
        this.phone = phone;
        this.email = email;
    }

    // getter和setter方法
    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getNation() {
        return nation;
    }

    public void setNation(String nation) {
        this.nation = nation;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getGrade() {
        return grade;
    }

    public void setGrade(int grade) {
        this.grade = grade;
    }

    public int getClazz() {
        return clazz;
    }

    public void setClazz(int clazz) {
        this.clazz = clazz;
    }

    public String getMajor() {
        return major;
    }

    public void setMajor(String major) {
        this.major = major;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    // 重写toString方法，用于输出信息
    @Override
    public String toString() {
        return "Student{" +
                "id='" + id + '\'' +
                ", name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", nation='" + nation + '\'' +
                ", age=" + age +
                ", grade=" + grade +
                ", clazz=" + clazz +
                ", major='" + major + '\'' +
                ", phone='" + phone + '\'' +
                ", email='" + email + '\'' +
                '}';
    }
}

2. 学生信息管理接口：StudentManager

import java.util.List;

public interface StudentManager {
    /**
     * 增加学生信息
     * @param student
     */
    void addStudent(Student student);

    /**
     * 删除学生信息
     * @param id
     */
    void deleteStudent(String id);

    /**
     * 修改学生信息
     * @param student
     */
    void updateStudent(Student student);

    /**
     * 查询学生信息
     * @param id
     * @return
     */
    Student queryStudent(String id);

    /**
     * 获取所有学生信息
     * @return
     */
    List<Student> getAllStudents();

    /**
     * 更新学生信息到文件
     */
    void updateToFile();
}

3. 学生信息管理实现类：StudentManagerImpl

import java.io.*;
import java.util.ArrayList;
import java.util.List;

public class StudentManagerImpl implements StudentManager {
    private List<Student> studentList = new ArrayList<>();
    private final String FILE_NAME = "out.txt";

    // 读取文件中的学生信息
    public StudentManagerImpl() {
        try {
            BufferedReader reader = new BufferedReader(new FileReader(FILE_NAME));
            String line;
            while ((line = reader.readLine()) != null) {
                String[] data = line.split(",");
                Student student = new Student(data[0], data[1], data[2], data[3], Integer.parseInt(data[4]), Integer.parseInt(data[5]), Integer.parseInt(data[6]), data[7], data[8], data[9]);
                studentList.add(student);
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void addStudent(Student student) {
        studentList.add(student);
        updateToFile();
    }

    @Override
    public void deleteStudent(String id) {
        for (int i = 0; i < studentList.size(); i++) {
            if (studentList.get(i).getId().equals(id)) {
                studentList.remove(i);
                break;
            }
        }
        updateToFile();
    }

    @Override
    public void updateStudent(Student student) {
        for (int i = 0; i < studentList.size(); i++) {
            if (studentList.get(i).getId().equals(student.getId())) {
                studentList.set(i, student);
                break;
            }
        }
        updateToFile();
    }

    @Override
    public Student queryStudent(String id) {
        for (Student student : studentList) {
            if (student.getId().equals(id)) {
                return student;
            }
        }
        return null;
    }

    @Override
    public List<Student> getAllStudents() {
        return studentList;
    }

    @Override
    public void updateToFile() {
        try {
            FileWriter writer = new FileWriter(FILE_NAME);
            for (Student student : studentList) {
                writer.write(student.getId() + "," + student.getName() + "," + student.getGender() + "," + student.getNation() + "," + student.getAge() + "," + student.getGrade() + "," + student.getClazz() + "," + student.getMajor() + "," + student.getPhone() + "," + student.getEmail() + "\n");
            }
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

4. 主程序：StudentManagementSystem

import java.util.List;
import java.util.Scanner;

public class StudentManagementSystem {
    private static StudentManagerImpl studentManager = new StudentManagerImpl();

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        while (true) {
            System.out.println("1. 添加学生信息");
            System.out.println("2. 删除学生信息");
            System.out.println("3. 修改学生信息");
            System.out.println("4. 查询学生信息");
            System.out.println("5. 显示所有学生信息");
            System.out.println("0. 退出程序");

            int option = scanner.nextInt();

            switch (option) {
                case 1:
                    addStudent(scanner);
                    break;
                case 2:
                    deleteStudent(scanner);
                    break;
                case 3:
                    updateStudent(scanner);
                    break;
                case 4:
                    queryStudent(scanner);
                    break;
                case 5:
                    showAllStudents();
                    break;
                case 0:
                    System.exit(0);
                default:
                    System.out.println("无效的选项，请重新输入");
            }
        }
    }

    private static void addStudent(Scanner scanner) {
        System.out.println("请输入学生信息（学号,姓名,性别,民族,年龄,年级,班级,专业,电话,E-mail）：");
        String id = scanner.next();
        String name = scanner.next();
        String gender = scanner.next();
        String nation = scanner.next();
        int age = scanner.nextInt();
        int grade = scanner.nextInt();
        int clazz = scanner.nextInt();
        String major = scanner.next();
        String phone = scanner.next();
        String email = scanner.next();
        Student student = new Student(id, name, gender, nation, age, grade, clazz, major, phone, email);
        studentManager.addStudent(student);
        System.out.println("添加成功！");
    }

    private static void deleteStudent(Scanner scanner) {
        System.out.println("请输入学生学号：");
        String id = scanner.next();
        studentManager.deleteStudent(id);
        System.out.println("删除成功！");
    }

    private static void updateStudent(Scanner scanner) {
        System.out.println("请输入学生信息（学号,姓名,性别,民族,年龄,年级,班级,专业,电话,E-mail）：");
        String id = scanner.next();
        String name = scanner.next();
        String gender = scanner.next();
        String nation = scanner.next();
        int age = scanner.nextInt();
        int grade = scanner.nextInt();
        int clazz = scanner.nextInt();
        String major = scanner.next();
        String phone = scanner.next();
        String email = scanner.next();
        Student student = new Student(id, name, gender, nation, age, grade, clazz, major, phone, email);
        studentManager.updateStudent(student);
        System.out.println("修改成功！");
    }

    private static void queryStudent(Scanner scanner) {
        System.out.println("请输入学生学号：");
        String id = scanner.next();
        Student student = studentManager.queryStudent(id);
        if (student != null) {
            System.out.println(student);
        } else {
            System.out.println("未找到该学生！");
        }
    }

    private static void showAllStudents() {
        List<Student> studentList = studentManager.getAllStudents();
        for (Student student : studentList) {
            System.out.println(student);
        }
    }
}

这样就实现了一个简单的学生信息管理系统，并将学生信息存储在文件 out.txt 中。需要注意的是，这里没有进行输入验证和异常处理等操作，实际应用中需要进行更加严格的处理。