用java写员工管理系统 员工属性：员工编号、员工姓名、性别、年龄、所在部门 1————员工添加 2————员工删除 3————员工信息修改 4————根据员工编号查询员工信息 5————查询所有员工信息 要求员工信息存储在TreeSet中，.按照员工编号进行升序排序

好的，这是一个比较典型的 Java 项目。员工管理系统可以使用面向对象的思想来实现，每个员工可以用一个类来表示，包含员工编号、姓名、性别、年龄、所在部门等属性。下面是一个简单的示例：

public class Employee implements Comparable<Employee> {
    private int id;
    private String name;
    private char gender;
    private int age;
    private String department;

    public Employee(int id, String name, char gender, int age, String department) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.age = age;
        this.department = department;
    }

    // getters and setters

    @Override
    public int compareTo(Employee other) {
        return Integer.compare(this.id, other.id);
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", name=" + name + ", gender=" + gender + ", age=" + age + ", department="
                + department + "]";
    }
}

这里实现了 `Comparable` 接口，以便可以按照员工编号进行排序。

接下来是员工管理系统的主类，包含添加、删除、修改、查询等操作。

import java.util.Scanner;
import java.util.TreeSet;

public class EmployeeManager {
    private TreeSet<Employee> employees;

    public EmployeeManager() {
        employees = new TreeSet<>();
    }

    public void addEmployee() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter employee id: ");
        int id = input.nextInt();
        System.out.print("Enter employee name: ");
        String name = input.next();
        System.out.print("Enter employee gender: ");
        char gender = input.next().charAt(0);
        System.out.print("Enter employee age: ");
        int age = input.nextInt();
        System.out.print("Enter employee department: ");
        String department = input.next();
        Employee employee = new Employee(id, name, gender, age, department);
        employees.add(employee);
        System.out.println("Employee added: " + employee);
    }

    public void removeEmployee() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter employee id: ");
        int id = input.nextInt();
        Employee employee = new Employee(id, "", ' ', 0, "");
        if (employees.contains(employee)) {
            employees.remove(employee);
            System.out.println("Employee removed: " + employee);
        } else {
            System.out.println("Employee not found with id: " + id);
        }
    }

    public void updateEmployee() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter employee id: ");
        int id = input.nextInt();
        Employee employee = new Employee(id, "", ' ', 0, "");
        if (employees.contains(employee)) {
            employees.remove(employee);
            System.out.println("Enter new employee details:");
            System.out.print("Enter employee name: ");
            String name = input.next();
            System.out.print("Enter employee gender: ");
            char gender = input.next().charAt(0);
            System.out.print("Enter employee age: ");
            int age = input.nextInt();
            System.out.print("Enter employee department: ");
            String department = input.next();
            Employee newEmployee = new Employee(id, name, gender, age, department);
            employees.add(newEmployee);
            System.out.println("Employee updated: " + newEmployee);
        } else {
            System.out.println("Employee not found with id: " + id);
        }
    }

    public void searchEmployee() {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter employee id: ");
        int id = input.nextInt();
        Employee employee = new Employee(id, "", ' ', 0, "");
        if (employees.contains(employee)) {
            System.out.println("Employee found: " + employee);
        } else {
            System.out.println("Employee not found with id: " + id);
        }
    }

    public void listEmployees() {
        System.out.println("List of all employees:");
        for (Employee employee : employees) {
            System.out.println(employee);
        }
    }

    public static void main(String[] args) {
        EmployeeManager manager = new EmployeeManager();
        Scanner input = new Scanner(System.in);
        while (true) {
            System.out.println("1. Add employee");
            System.out.println("2. Remove employee");
            System.out.println("3. Update employee");
            System.out.println("4. Search employee");
            System.out.println("5. List all employees");
            System.out.println("0. Exit");
            System.out.print("Enter your choice: ");
            int choice = input.nextInt();
            switch (choice) {
            case 1:
                manager.addEmployee();
                break;
            case 2:
                manager.removeEmployee();
                break;
            case 3:
                manager.updateEmployee();
                break;
            case 4:
                manager.searchEmployee();
                break;
            case 5:
                manager.listEmployees();
                break;
            case 0:
                System.out.println("Exiting program...");
                System.exit(0);
            default:
                System.out.println("Invalid choice!");
            }
        }
    }
}

这里使用了一个 `TreeSet` 来存储所有员工信息，每个操作都可以通过调用 `TreeSet` 的方法来实现。注意在每个操作中，都需要先根据员工编号构造一个临时的 `Employee` 对象，以便可以在 `TreeSet` 中进行查找或删除。