用java设计个学生管理系统，能对学生成绩进行增删改查，并用io将数据保存

好的，我可以为您提供一份简单的Java代码，实现学生管理系统并通过IO流进行数据的保存。

首先，我们需要定义一个学生类，包括学生的姓名、学号、性别和成绩等信息，代码如下：

import java.io.Serializable;

public class Student implements Serializable {
    private String name;
    private String id;
    private String gender;
    private float score;

    public Student(String name, String id, String gender, float score) {
        this.name = name;
        this.id = id;
        this.gender = gender;
        this.score = score;
    }

    public String getName() {
        return name;
    }

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

    public String getId() {
        return id;
    }

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

    public String getGender() {
        return gender;
    }

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

    public float getScore() {
        return score;
    }

    public void setScore(float score) {
        this.score = score;
    }
}

然后，我们需要编写一个学生管理类，实现学生信息的增删改查和数据的保存，代码如下：

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

public class StudentManager {
    private List<Student> studentList;
    private String filename;

    public StudentManager(String filename) {
        this.filename = filename;
        this.studentList = load();
    }

    private List<Student> load() {
        List<Student> list = new ArrayList<>();
        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filename))) {
            list = (List<Student>) ois.readObject();
        } catch (IOException | ClassNotFoundException e) {
            System.out.println("Load error: " + e.getMessage());
        }
        return list;
    }

    private void save() {
        try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
            oos.writeObject(studentList);
        } catch (IOException e) {
            System.out.println("Save error: " + e.getMessage());
        }
    }

    public void add() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the student name: ");
        String name = scanner.nextLine();
        System.out.print("Enter the student ID: ");
        String id = scanner.nextLine();
        System.out.print("Enter the student gender: ");
        String gender = scanner.nextLine();
        System.out.print("Enter the student score: ");
        float score = scanner.nextFloat();
        scanner.nextLine();
        Student student = new Student(name, id, gender, score);
        studentList.add(student);
        save();
    }

    public void delete() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the student ID: ");
        String id = scanner.nextLine();
        boolean found = false;
        for (Student student : studentList) {
            if (student.getId().equals(id)) {
                studentList.remove(student);
                found = true;
                break;
            }
        }
        if (!found) {
            System.out.println("Student not found!");
        } else {
            save();
        }
    }

    public void update() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the student ID: ");
        String id = scanner.nextLine();
        boolean found = false;
        for (Student student : studentList) {
            if (student.getId().equals(id)) {
                System.out.print("Enter the new student name: ");
                String name = scanner.nextLine();
                System.out.print("Enter the new student gender: ");
                String gender = scanner.nextLine();
                System.out.print("Enter the new student score: ");
                float score = scanner.nextFloat();
                scanner.nextLine();
                student.setName(name);
                student.setGender(gender);
                student.setScore(score);
                found = true;
                break;
            }
        }
        if (!found) {
            System.out.println("Student not found!");
        } else {
            save();
        }
    }

    public void search() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the student ID: ");
        String id = scanner.nextLine();
        boolean found = false;
        for (Student student : studentList) {
            if (student.getId().equals(id)) {
                System.out.println("Name: " + student.getName() + ", Gender: " + student.getGender() + ", Score: " + student.getScore());
                found = true;
                break;
            }
        }
        if (!found) {
            System.out.println("Student not found!");
        }
    }
}

最后，在主函数中，我们可以创建一个学生管理类对象，用于处理用户输入的命令，代码如下：

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the filename to save the student info: ");
        String filename = scanner.nextLine();
        StudentManager manager = new StudentManager(filename);
        while (true) {
            System.out.println("1. Add student");
            System.out.println("2. Delete student");
            System.out.println("3. Update student");
            System.out.println("4. Search student");
            System.out.println("5. Exit");
            System.out.print("Enter your choice: ");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 1:
                    manager.add();
                    break;
                case 2:
                    manager.delete();
                    break;
                case 3:
                    manager.update();
                    break;
                case 4:
                    manager.search();
                    break;
                case 5:
                    System.exit(0);
                default:
                    System.out.println("Invalid choice!");
            }
        }
    }
}

这样，我们就实现了一个简单的学生管理系统，并通过IO流将数据保存到文件中。