用java写一个信息管理系统

好的，下面给您提供一个简单的 Java 信息管理系统示例代码：

import java.util.ArrayList;
import java.util.Scanner;

public class StudentInfoSystem {
    private ArrayList<Student> students;

    public StudentInfoSystem() {
        students = new ArrayList<Student>();
    }

    public void addStudent(Student student) {
        students.add(student);
    }

    public void removeStudent(int index) {
        students.remove(index);
    }

    public void displayAllStudents() {
        if(students.size() == 0) {
            System.out.println("没有学生信息！");
        } else {
            for(int i=0; i<students.size(); i++) {
                System.out.println(students.get(i));
            }
        }
    }

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

        while(true) {
            System.out.println("请输入操作序号：");
            System.out.println("1. 添加学生信息");
            System.out.println("2. 删除学生信息");
            System.out.println("3. 显示所有学生信息");
            System.out.println("4. 退出程序");

            int choice = scanner.nextInt();

            switch(choice) {
                case 1:
                    System.out.println("请输入学生姓名：");
                    String name = scanner.next();
                    System.out.println("请输入学生年龄：");
                    int age = scanner.nextInt();
                    System.out.println("请输入学生性别：");
                    String gender = scanner.next();
                    Student student = new Student(name, age, gender);
                    system.addStudent(student);
                    System.out.println("学生信息添加成功！");
                    break;
                case 2:
                    if(system.students.size() == 0) {
                        System.out.println("没有学生信息！");
                    } else {
                        System.out.println("请选择要删除的学生序号：");
                        for(int i=0; i<system.students.size(); i++) {
                            System.out.println(i + ". " + system.students.get(i).getName());
                        }
                        int index = scanner.nextInt();
                        system.removeStudent(index);
                        System.out.println("学生信息删除成功！");
                    }
                    break;
                case 3:
                    system.displayAllStudents();
                    break;
                case 4:
                    System.exit(0);
                default:
                    System.out.println("输入有误，请重新输入！");
            }
        }
    }
}

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

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

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public String getGender() {
        return gender;
    }

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

这个信息管理系统可以实现添加、删除和显示学生信息的功能，您可以根据自己的需要进行修改和完善。