用java编写一个管理系统

好的，管理系统可以有很多种类型，例如图书管理系统、学生管理系统、员工管理系统等等。这里我以学生管理系统为例，给您提供一个简单的代码框架。

import java.util.Scanner;

public class StudentManagementSystem {
    private static final int MAX_STUDENTS = 100; // 最大学生数
    private static Student[] students = new Student[MAX_STUDENTS]; // 存储学生信息的数组
    private static int numStudents = 0; // 当前学生数

    public static void main(String[] args) {
        while (true) {
            System.out.println("请选择操作：");
            System.out.println("1. 添加学生");
            System.out.println("2. 删除学生");
            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. 退出系统");

            Scanner scanner = new Scanner(System.in);
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    addStudent();
                    break;
                case 2:
                    deleteStudent();
                    break;
                case 3:
                    modifyStudent();
                    break;
                case 4:
                    searchStudent();
                    break;
                case 5:
                    displayAllStudents();
                    break;
                case 0:
                    System.out.println("谢谢使用！");
                    return;
                default:
                    System.out.println("输入有误，请重新选择！");
                    break;
            }
        }
    }

    // 添加学生
    private static void addStudent() {
        if (numStudents >= MAX_STUDENTS) {
            System.out.println("学生数已达到上限！");
            return;
        }

        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入学号：");
        String id = scanner.nextLine();
        System.out.println("请输入姓名：");
        String name = scanner.nextLine();
        System.out.println("请输入性别：");
        String gender = scanner.nextLine();
        System.out.println("请输入年龄：");
        int age = scanner.nextInt();

        Student student = new Student(id, name, gender, age);
        students[numStudents] = student;
        numStudents++;

        System.out.println("添加成功！");
    }

    // 删除学生
    private static void deleteStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要删除的学生学号：");
        String id = scanner.nextLine();

        for (int i = 0; i < numStudents; i++) {
            if (students[i].getId().equals(id)) {
                for (int j = i; j < numStudents - 1; j++) {
                    students[j] = students[j + 1];
                }
                numStudents--;
                System.out.println("删除成功！");
                return;
            }
        }

        System.out.println("未找到该学生！");
    }

    // 修改学生信息
    private static void modifyStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要修改的学生学号：");
        String id = scanner.nextLine();

        for (int i = 0; i < numStudents; i++) {
            if (students[i].getId().equals(id)) {
                System.out.println("请输入新的姓名：");
                String name = scanner.nextLine();
                System.out.println("请输入新的性别：");
                String gender = scanner.nextLine();
                System.out.println("请输入新的年龄：");
                int age = scanner.nextInt();

                students[i].setName(name);
                students[i].setGender(gender);
                students[i].setAge(age);

                System.out.println("修改成功！");
                return;
            }
        }

        System.out.println("未找到该学生！");
    }

    // 查询学生信息
    private static void searchStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要查询的学生学号：");
        String id = scanner.nextLine();

        for (int i = 0; i < numStudents; i++) {
            if (students[i].getId().equals(id)) {
                System.out.println(students[i]);
                return;
            }
        }

        System.out.println("未找到该学生！");
    }

    // 显示所有学生信息
    private static void displayAllStudents() {
        for (int i = 0; i < numStudents; i++) {
            System.out.println(students[i]);
        }
    }
}

class Student {
    private String id; // 学号
    private String name; // 姓名
    private String gender; // 性别
    private int age; // 年龄

    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 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 int getAge() {
        return age;
    }

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

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

这个简单的学生管理系统实现了添加、删除、修改、查询和显示所有学生信息的功能。您可以根据自己的需求进行修改和扩展。