学生管理系统的代码

好的，下面给您提供一个基于 Java 面向对象编程思想实现的简单学生管理系统的代码，其中使用文件存储学生信息。这只是一个简单的示例，您可以根据自己的需求和实际情况进行修改和完善。

import java.io.*;
import java.util.*;

// 定义学生类
class Student {
    private String id;
    private String name;
    private String gender;
    private int age;

    public Student(String id, String name, String gender, int age) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getGender() {
        return gender;
    }

    public int getAge() {
        return age;
    }

    @Override
    public String toString() {
        return "学号：" + id + "，姓名：" + name + "，性别：" + gender + "，年龄：" + age;
    }
}

// 定义学生管理类
class StudentManager {
    private List<Student> students;
    private String filename;

    public StudentManager(String filename) {
        this.filename = filename;
        students = new ArrayList<>();
        load();
    }

    // 加载学生信息
    private void load() {
        try (BufferedReader br = new BufferedReader(new FileReader(filename))) {
            String line;
            while ((line = br.readLine()) != null) {
                String[] data = line.split(",");
                Student student = new Student(data[0], data[1], data[2], Integer.parseInt(data[3]));
                students.add(student);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 保存学生信息
    private void save() {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter(filename))) {
            for (Student student : students) {
                bw.write(student.getId() + "," + student.getName() + "," + student.getGender() + "," + student.getAge());
                bw.newLine();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 添加学生信息
    public void add(Student student) {
        students.add(student);
        save();
    }

    // 删除学生信息
    public void remove(String id) {
        Iterator<Student> it = students.iterator();
        while (it.hasNext()) {
            Student student = it.next();
            if (student.getId().equals(id)) {
                it.remove();
                break;
            }
        }
        save();
    }

    // 修改学生信息
    public void update(String id, String name, String gender, int age) {
        for (Student student : students) {
            if (student.getId().equals(id)) {
                student = new Student(id, name, gender, age);
                break;
            }
        }
        save();
    }

    // 查询学生信息
    public List<Student> query(String id, String name, String gender, int age) {
        List<Student> result = new ArrayList<>();
        for (Student student : students) {
            if ((id == null || student.getId().equals(id)) &&
                    (name == null || student.getName().equals(name)) &&
                    (gender == null || student.getGender().equals(gender)) &&
                    (age == -1 || student.getAge() == age)) {
                result.add(student);
            }
        }
        return result;
    }

    // 显示学生信息
    public void display(List<Student> students) {
        if (students.size() == 0) {
            System.out.println("没有找到符合条件的学生！");
        } else {
            for (Student student : students) {
                System.out.println(student.toString());
            }
        }
    }
}

// 定义主程序类
public class Main {
    public static void main(String[] args) {
        StudentManager manager = new StudentManager("students.txt");
        Scanner scanner = new Scanner(System.in);

        while (true) {
            System.out.println("请选择操作：1.添加学生 2.删除学生 3.修改学生 4.查询学生 5.退出");
            int option = scanner.nextInt();
            switch (option) {
                case 1:
                    System.out.println("请输入学号：");
                    String id = scanner.next();
                    System.out.println("请输入姓名：");
                    String name = scanner.next();
                    System.out.println("请输入性别：");
                    String gender = scanner.next();
                    System.out.println("请输入年龄：");
                    int age = scanner.nextInt();
                    Student student = new Student(id, name, gender, age);
                    manager.add(student);
                    System.out.println("添加成功！");
                    break;
                case 2:
                    System.out.println("请输入学号：");
                    id = scanner.next();
                    manager.remove(id);
                    System.out.println("删除成功！");
                    break;
                case 3:
                    System.out.println("请输入学号：");
                    id = scanner.next();
                    System.out.println("请输入姓名：");
                    name = scanner.next();
                    System.out.println("请输入性别：");
                    gender = scanner.next();
                    System.out.println("请输入年龄：");
                    age = scanner.nextInt();
                    manager.update(id, name, gender, age);
                    System.out.println("修改成功！");
                    break;
                case 4:
                    System.out.println("请输入学号（不输入则不限制）：");
                    id = scanner.next();
                    System.out.println("请输入姓名（不输入则不限制）：");
                    name = scanner.next();
                    System.out.println("请输入性别（不输入则不限制）：");
                    gender = scanner.next();
                    System.out.println("请输入年龄（不输入则不限制）：");
                    age = scanner.nextInt();
                    List<Student> students = manager.query(id.equals("") ? null : id, name.equals("") ? null : name, gender.equals("") ? null : gender, age == 0 ? -1 : age);
                    manager.display(students);
                    break;
                case 5:
                    System.exit(0);
                    break;
                default:
                    System.out.println("输入错误，请重新选择！");
            }
        }
    }
}

以上代码只是一个简单的示例，可能存在不足和需要改进的地方，仅供参考。