使用异常知识，来写一段Java代码来实现学生信息管理系统

当实现学生信息管理系统时，可以利用异常处理来处理可能发生的错误和异常情况。以下是一个简单的Java代码示例，演示如何利用异常处理来实现学生信息管理系统：

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

class Student {
    private String name;
    private int age;
    private String gender;
    private String studentId;

    // 构造函数
    public Student(String name, int age, String gender, String studentId) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.studentId = studentId;
    }

    // Getter 和 Setter 方法

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

    public String getGender() {
        return gender;
    }

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

    public String getStudentId() {
        return studentId;
    }

    public void setStudentId(String studentId) {
        this.studentId = studentId;
    }
}

class StudentManagementSystem {
    private List<Student> students;

    // 构造函数
    public StudentManagementSystem() {
        students = new ArrayList<>();
    }

    // 添加学生信息
    public void addStudent(Student student) throws Exception {
        // 检查学号是否重复
        for (Student s : students) {
            if (s.getStudentId().equals(student.getStudentId())) {
                throw new Exception("学号重复");
            }
        }
        students.add(student);
    }

    // 删除学生信息
    public void deleteStudent(String studentId) throws Exception {
        boolean found = false;
        for (Student student : students) {
            if (student.getStudentId().equals(studentId)) {
                students.remove(student);
                found = true;
                break;
            }
        }
        if (!found) {
            throw new Exception("学生信息不存在");
        }
    }

    // 修改学生信息
    public void updateStudent(String studentId, Student newStudent) throws Exception {
        boolean found = false;
        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getStudentId().equals(studentId)) {
                students.set(i, newStudent);
                found = true;
                break;
            }
        }
        if (!found) {
            throw new Exception("学生信息不存在");
        }
    }

    // 查询学生信息
    public Student findStudent(String studentId) throws Exception {
        for (Student student : students) {
            if (student.getStudentId().equals(studentId)) {
                return student;
            }
        }
        throw new Exception("学生信息不存在");
    }

    // 保存学生信息到文件
    public void saveToFile(String filename) throws IOException {
        try (PrintWriter writer = new PrintWriter(new FileWriter(filename))) {
            for (Student student : students) {
                writer.println(student.getName() + "," + student.getAge() + "," + student.getGender() + "," + student.getStudentId());
            }
        }
    }

    // 从文件加载学生信息
    public void loadFromFile(String filename) throws IOException {
        try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
            String line;
            while ((line = reader.readLine()) != null) {
                String[] parts = line.split(",");
                if (parts.length == 4) {
                    String name = parts[0];
                    int age = Integer.parseInt(parts[1]);
                    String gender = parts[2];
                    String studentId = parts[3];
                    students.add(new Student(name, age, gender, studentId));
                }
            }
        }
    }
}

public class Main {
    public static void main(String[] args) {
        StudentManagementSystem system = new StudentManagementSystem();
        try {
            // 添加学生
            system.addStudent(new Student("张三", 18, "男", "10001"));
            system.addStudent(new Student("李四", 19, "女", "10002"));
            system.addStudent(new Student("王五", 20, "男", "10003"));
            
            // 保存学生信息到文件
            system.saveToFile("students.txt");
            
            // 从文件加载学生信息
            system.loadFromFile("students.txt");
            
            // 查询学生信息
            Student student = system.findStudent("10002");
            System.out.println("学生信息：" + student.getName() + " " + student.getAge() + " " + student.getGender());
            
            // 修改学生信息
            system.updateStudent("10002", new Student("李四", 20, "女", "10002"));
            
            // 删除学生信息
            system.deleteStudent("10003");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

以上示例代码实现了一个简单的学生信息管理系统，包括添加、删除、修改和查询学生信息的功能，并将学生信息保存在txt文件中。同时，使用了异常处理来处理可能发生的错误和异常情况，提高程序的稳定性和健壮性。