请基于Java写出一个简单的人事管理系统

好的，以下是一个简单的人事管理系统的Java代码示例：

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

class Employee {
    private int id;
    private String name;
    private int age;
    private String position;
    private double salary;

    public Employee(int id, String name, int age, String position, double salary) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.position = position;
        this.salary = salary;
    }

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public String getPosition() {
        return position;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

    public String toString() {
        return "ID: " + id + "\nName: " + name + "\nAge: " + age + "\nPosition: " + position + "\nSalary: " + salary;
    }
}

public class HRSystem {
    private ArrayList<Employee> employees;

    public HRSystem() {
        employees = new ArrayList<>();
    }

    public void addEmployee(Employee e) {
        employees.add(e);
    }

    public void removeEmployee(int id) {
        for (Employee e : employees) {
            if (e.getId() == id) {
                employees.remove(e);
                break;
            }
        }
    }

    public void displayAllEmployees() {
        for (Employee e : employees) {
            System.out.println(e.toString());
        }
    }

    public void updateEmployeeSalary(int id, double newSalary) {
        for (Employee e : employees) {
            if (e.getId() == id) {
                e.setSalary(newSalary);
                break;
            }
        }
    }

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

        while (true) {
            System.out.println("1. Add Employee");
            System.out.println("2. Remove Employee");
            System.out.println("3. Display All Employees");
            System.out.println("4. Update Employee Salary");
            System.out.println("5. Exit");

            System.out.print("\nEnter your choice: ");
            int choice = scanner.nextInt();

            switch (choice) {
                case 1:
                    System.out.print("Enter employee ID: ");
                    int id = scanner.nextInt();
                    System.out.print("Enter employee name: ");
                    String name = scanner.next();
                    System.out.print("Enter employee age: ");
                    int age = scanner.nextInt();
                    System.out.print("Enter employee position: ");
                    String position = scanner.next();
                    System.out.print("Enter employee salary: ");
                    double salary = scanner.nextDouble();

                    Employee e = new Employee(id, name, age, position, salary);
                    hrSystem.addEmployee(e);
                    System.out.println("\nEmployee added successfully!\n");
                    break;
                case 2:
                    System.out.print("Enter employee ID: ");
                    int removeId = scanner.nextInt();

                    hrSystem.removeEmployee(removeId);
                    System.out.println("\nEmployee removed successfully!\n");
                    break;
                case 3:
                    hrSystem.displayAllEmployees();
                    break;
                case 4:
                    System.out.print("Enter employee ID: ");
                    int updateId = scanner.nextInt();
                    System.out.print("Enter new salary: ");
                    double newSalary = scanner.nextDouble();

                    hrSystem.updateEmployeeSalary(updateId, newSalary);
                    System.out.println("\nEmployee salary updated successfully!\n");
                    break;
                case 5:
                    System.out.println("\nExiting HR System...");
                    System.exit(0);
                default:
                    System.out.println("\nInvalid choice. Please try again.\n");
            }
        }
    }
}

这个人事管理系统可以添加、删除、显示和更新员工信息，包括ID、姓名、年龄、职位和工资。用户可以通过菜单选择操作，所有员工信息被存储在一个ArrayList中。