用Java写出一个学生请假管理系统

好的，以下是一个简单的学生请假管理系统的Java代码：

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

public class LeaveManagementSystem {

    public static void main(String[] args) {
        ArrayList<Student> students = new ArrayList<>();
        Scanner scanner = new Scanner(System.in);
        int choice;
        do {
            System.out.println("1. 添加学生");
            System.out.println("2. 查看所有学生");
            System.out.println("3. 请假");
            System.out.println("4. 退出");

            System.out.print("请输入你的选择: ");
            choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    addStudent(students);
                    break;
                case 2:
                    viewAllStudents(students);
                    break;
                case 3:
                    takeLeave(students);
                    break;
                case 4:
                    System.out.println("谢谢使用！");
                    break;
                default:
                    System.out.println("无效的选择，请重新输入！");
                    break;
            }
        } while (choice != 4);
    }

    private static void addStudent(ArrayList<Student> students) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入学生姓名: ");
        String name = scanner.nextLine();
        Student student = new Student(name);
        students.add(student);
        System.out.println("添加成功！");
    }

    private static void viewAllStudents(ArrayList<Student> students) {
        if (students.size() == 0) {
            System.out.println("当前没有学生！");
            return;
        }
        for (int i = 0; i < students.size(); i++) {
            System.out.println(i + 1 + ". " + students.get(i).getName());
        }
    }

    private static void takeLeave(ArrayList<Student> students) {
        Scanner scanner = new Scanner(System.in);
        viewAllStudents(students);
        System.out.print("请选择请假的学生编号: ");
        int index = scanner.nextInt();
        if (index < 1 || index > students.size()) {
            System.out.println("无效的学生编号！");
            return;
        }
        Student student = students.get(index - 1);
        System.out.print("请输入请假天数: ");
        int days = scanner.nextInt();
        if (days <= 0) {
            System.out.println("无效的请假天数！");
            return;
        }
        student.takeLeave(days);
        System.out.println(student.getName() + "请假成功！");
    }
}

class Student {
    private String name;
    private int leaveDays;

    public Student(String name) {
        this.name = name;
        this.leaveDays = 0;
    }

    public String getName() {
        return name;
    }

    public void takeLeave(int days) {
        this.leaveDays += days;
    }

    public int getLeaveDays() {
        return leaveDays;
    }
}

该系统包含以下基本功能：

1. 添加学生
2. 查看所有学生
3. 请假
4. 退出

学生类包含姓名和已请假天数两个属性，以及请假方法。主程序中使用ArrayList来存储所有学生的信息，用户可以通过选择菜单来进行相应的操作。