头哥string 类型

String是一种数据类型，在许多编程语言中都有，用于表示一串字符。在Java、C++、Python等语言中，String类型都是内置的，可以直接使用。String类型通常用于存储文本数据，例如电子邮件、网页内容、用户名等。它具有许多有用的方法，例如字符串拼接、字符串比较、字符串查找等。在编程中，String类型是非常常见的数据类型之一。

相关问题

头哥javastring类

Java中的String类是一个非常重要的类，它代表了字符串类型的数据。String类是不可变的，这意味着一旦创建了一个字符串对象，就不能更改它的值。String类提供了许多有用的方法来操作字符串，例如substring()、length()、indexOf()等等。

另外，Java中还有一个StringBuffer类，它也代表了字符串类型的数据，但是与String类不同的是，StringBuffer类是可变的，这意味着可以更改它的值。StringBuffer类提供了许多有用的方法来操作字符串，例如append()、insert()、reverse()等等。

在提供的引用中，给出了一个使用StringBuffer类的例子，它将输入的字符串中的每个单词都反转，并返回一个新的字符串。具体实现可以参考以下代码：

public class Reverse {
    public static StringBuffer start(String data) {
        StringBuffer ans = new StringBuffer();
        String[] words = data.split(" ");
        for (int i = 0; i < words.length; i++) {
            StringBuffer wordcaps = new StringBuffer(words[i]);
            ans.append(wordcaps.reverse());
            ans.append(" ");
        }
        return ans;
    }
}

头哥java继承和多态之综合练习

好的，下面给你一个综合练习，希望能够帮助你熟悉Java继承和多态的使用。

题目描述：

设计一个简单的员工管理系统，要求实现员工信息录入、查看、修改和删除等功能。该系统包含以下员工类型：

1.普通员工：包含员工编号、姓名、性别、年龄、职位、基本工资等属性，以及计算薪水的方法（基本工资 + 奖金）。

2.经理：包含员工编号、姓名、性别、年龄、职位、基本工资、奖金、部门等属性，以及计算薪水的方法（基本工资 + 奖金 + 年度绩效）。

3.销售员：包含员工编号、姓名、性别、年龄、职位、基本工资、销售额、提成比例等属性，以及计算薪水的方法（基本工资 + 销售额 * 提成比例）。

要求：

1.使用继承和多态的概念实现员工类的设计。

2.使用ArrayList集合来存储员工信息。

3.实现员工信息的增删改查功能。

4.实现员工薪水的计算和显示功能。

5.使用菜单方式来实现系统的交互。

代码实现：

首先，我们需要先定义一个父类Employee，包含员工编号、姓名、性别、年龄、职位、基本工资等属性，以及计算薪水的方法（基本工资 + 奖金）。

public class Employee {
    private String id; // 员工编号
    private String name; // 姓名
    private String sex; // 性别
    private int age; // 年龄
    private String position; // 职位
    private double salary; // 基本工资

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

    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 getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public int getAge() {
        return age;
    }

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

    public String getPosition() {
        return position;
    }

    public void setPosition(String position) {
        this.position = position;
    }

    public double getSalary() {
        return salary;
    }

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

    public double calcSalary() {
        return salary;
    }
}

接下来，我们分别定义三个子类，分别为Manager、Salesman和NormalEmployee，分别添加各自特有的属性和计算薪水的方法。

public class Manager extends Employee {
    private double bonus; // 奖金
    private double performance; // 年度绩效
    private String department; // 部门

    public Manager(String id, String name, String sex, int age, String position, double salary, double bonus,
            double performance, String department) {
        super(id, name, sex, age, position, salary);
        this.bonus = bonus;
        this.performance = performance;
        this.department = department;
    }

    public double getBonus() {
        return bonus;
    }

    public void setBonus(double bonus) {
        this.bonus = bonus;
    }

    public double getPerformance() {
        return performance;
    }

    public void setPerformance(double performance) {
        this.performance = performance;
    }

    public String getDepartment() {
        return department;
    }

    public void setDepartment(String department) {
        this.department = department;
    }

    @Override
    public double calcSalary() {
        return super.calcSalary() + bonus + performance;
    }
}

public class Salesman extends Employee {
    private double sales; // 销售额
    private double commission; // 提成比例

    public Salesman(String id, String name, String sex, int age, String position, double salary, double sales,
            double commission) {
        super(id, name, sex, age, position, salary);
        this.sales = sales;
        this.commission = commission;
    }

    public double getSales() {
        return sales;
    }

    public void setSales(double sales) {
        this.sales = sales;
    }

    public double getCommission() {
        return commission;
    }

    public void setCommission(double commission) {
        this.commission = commission;
    }

    @Override
    public double calcSalary() {
        return super.calcSalary() + sales * commission;
    }
}

public class NormalEmployee extends Employee {
    public NormalEmployee(String id, String name, String sex, int age, String position, double salary) {
        super(id, name, sex, age, position, salary);
    }
}

接下来，我们需要实现员工信息的增删改查功能，以及员工薪水的计算和显示功能，具体实现如下：

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

public class EmployeeSystem {
    private ArrayList<Employee> employees = new ArrayList<>(); // 员工列表

    // 添加员工
    public void addEmployee(Employee employee) {
        employees.add(employee);
    }

    // 删除员工
    public void deleteEmployee(String id) {
        for (int i = 0; i < employees.size(); i++) {
            Employee employee = employees.get(i);
            if (employee.getId().equals(id)) {
                employees.remove(i);
                break;
            }
        }
    }

    // 修改员工
    public void updateEmployee(String id, Employee employee) {
        for (int i = 0; i < employees.size(); i++) {
            Employee e = employees.get(i);
            if (e.getId().equals(id)) {
                e.setName(employee.getName());
                e.setSex(employee.getSex());
                e.setAge(employee.getAge());
                e.setPosition(employee.getPosition());
                e.setSalary(employee.getSalary());

                if (employee instanceof Manager) {
                    Manager manager = (Manager) employee;
                    ((Manager) e).setBonus(manager.getBonus());
                    ((Manager) e).setPerformance(manager.getPerformance());
                    ((Manager) e).setDepartment(manager.getDepartment());
                } else if (employee instanceof Salesman) {
                    Salesman salesman = (Salesman) employee;
                    ((Salesman) e).setSales(salesman.getSales());
                    ((Salesman) e).setCommission(salesman.getCommission());
                }

                break;
            }
        }
    }

    // 查询员工
    public Employee queryEmployee(String id) {
        for (int i = 0; i < employees.size(); i++) {
            Employee employee = employees.get(i);
            if (employee.getId().equals(id)) {
                return employee;
            }
        }
        return null;
    }

    // 计算所有员工的薪水
    public double calcAllSalary() {
        double totalSalary = 0;
        for (int i = 0; i < employees.size(); i++) {
            Employee employee = employees.get(i);
            totalSalary += employee.calcSalary();
        }
        return totalSalary;
    }

    // 显示所有员工的信息
    public void showAllEmployees() {
        for (int i = 0; i < employees.size(); i++) {
            Employee employee = employees.get(i);
            System.out.println("员工编号：" + employee.getId());
            System.out.println("姓名：" + employee.getName());
            System.out.println("性别：" + employee.getSex());
            System.out.println("年龄：" + employee.getAge());
            System.out.println("职位：" + employee.getPosition());
            System.out.println("工资：" + employee.calcSalary());
            System.out.println("--------------------------");
        }
    }

    // 显示菜单
    public void showMenu() {
        System.out.println("==========员工管理系统==========");
        System.out.println("1.添加员工");
        System.out.println("2.删除员工");
        System.out.println("3.修改员工");
        System.out.println("4.查询员工");
        System.out.println("5.显示所有员工");
        System.out.println("6.计算所有员工的薪水");
        System.out.println("0.退出系统");
        System.out.println("请选择操作：");
    }

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

        while (true) {
            es.showMenu();
            int choice = scanner.nextInt();
            switch (choice) {
            case 1:
                System.out.println("请输入员工类型（1.普通员工 2.经理 3.销售员）：");
                int type = scanner.nextInt();
                System.out.println("请输入员工编号：");
                String id = scanner.next();
                System.out.println("请输入员工姓名：");
                String name = scanner.next();
                System.out.println("请输入员工性别：");
                String sex = scanner.next();
                System.out.println("请输入员工年龄：");
                int age = scanner.nextInt();
                System.out.println("请输入员工职位：");
                String position = scanner.next();
                System.out.println("请输入员工基本工资：");
                double salary = scanner.nextDouble();

                Employee employee = null;
                if (type == 1) {
                    employee = new NormalEmployee(id, name, sex, age, position, salary);
                } else if (type == 2) {
                    System.out.println("请输入员工奖金：");
                    double bonus = scanner.nextDouble();
                    System.out.println("请输入员工年度绩效：");
                    double performance = scanner.nextDouble();
                    System.out.println("请输入员工部门：");
                    String department = scanner.next();
                    employee = new Manager(id, name, sex, age, position, salary, bonus, performance, department);
                } else if (type == 3) {
                    System.out.println("请输入员工销售额：");
                    double sales = scanner.nextDouble();
                    System.out.println("请输入员工提成比例：");
                    double commission = scanner.nextDouble();
                    employee = new Salesman(id, name, sex, age, position, salary, sales, commission);
                }

                es.addEmployee(employee);
                System.out.println("添加成功！");
                break;
            case 2:
                System.out.println("请输入员工编号：");
                id = scanner.next();
                es.deleteEmployee(id);
                System.out.println("删除成功！");
                break;
            case 3:
                System.out.println("请输入员工编号：");
                id = scanner.next();
                employee = es.queryEmployee(id);
                if (employee == null) {
                    System.out.println("员工不存在！");
                } else {
                    System.out.println("请输入员工姓名：");
                    name = scanner.next();
                    System.out.println("请输入员工性别：");
                    sex = scanner.next();
                    System.out.println("请输入员工年龄：");
                    age = scanner.nextInt();
                    System.out.println("请输入员工职位：");
                    position = scanner.next();
                    System.out.println("请输入员工基本工资：");
                    salary = scanner.nextDouble();

                    if (employee instanceof Manager) {
                        System.out.println("请输入员工奖金：");
                        double bonus = scanner.nextDouble();
                        System.out.println("请输入员工年度绩效：");
                        double performance = scanner.nextDouble();
                        System.out.println("请输入员工部门：");
                        String department = scanner.next();
                        Manager manager = new Manager(id, name, sex, age, position, salary, bonus, performance,
                                department);
                        es.updateEmployee(id, manager);
                    } else if (employee instanceof Salesman) {
                        System.out.println("请输入员工销售额：");
                        double sales = scanner.nextDouble();
                        System.out.println("请输入员工提成比例：");
                        double commission = scanner.nextDouble();
                        Salesman salesman = new Salesman(id, name, sex, age, position, salary, sales, commission);
                        es.updateEmployee(id, salesman);
                    } else {
                        NormalEmployee normalEmployee = new NormalEmployee(id, name, sex, age, position, salary);
                        es.updateEmployee(id, normalEmployee);
                    }
                    System.out.println("修改成功！");
                }
                break;
            case 4:
                System.out.println("请输入员工编号：");
                id = scanner.next();
                employee = es.queryEmployee(id);
                if (employee == null) {
                    System.out.println("员工不存在！");
                } else {
                    System.out.println("员工编号：" + employee.getId());
                    System.out.println("姓名：" + employee.getName());
                    System.out.println("性别：" + employee.getSex());
                    System.out.println("年龄：" + employee.getAge());
                    System.out.println("职位：" + employee.getPosition());
                    System.out.println("工资：" + employee.calcSalary());
                }
                break;
            case 5:
                es.showAllEmployees();
                break;
            case 6:
                double totalSalary = es.calcAllSalary();
                System.out.println("所有员工的薪水总和为：" + totalSalary);
                break;
            case 0:
                System.exit(0);
            default:
                System.out.println("输入有误，请重新输入！");
            }
        }
    }
}

这样，一个简单的员工管理系统就完成了。你可以尝试运行这个程序，体验一下它的功能。