package io.github.atengk.oop;

/**
 * 学生类，用于演示面向对象中的属性和行为
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Student {

    private String name;

    private Integer age;

    public Student(String name, Integer age) {
        this.name = name;
        this.age = age;
    }

    public void introduce() {
        System.out.println("大家好，我是" + name + "，今年" + age + "岁。");
    }
}

package io.github.atengk.oop;

/**
 * 学生测试类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class StudentTest {

    public static void main(String[] args) {
        Student student = new Student("张三", 18);
        student.introduce();
    }
}

package io.github.atengk.oop;

/**
 * 面向过程登录示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ProcessLoginDemo {

    public static void main(String[] args) {
        String username = "admin";
        String password = "123456";

        if ("admin".equals(username) && "123456".equals(password)) {
            System.out.println("登录成功");
        } else {
            System.out.println("用户名或密码错误");
        }
    }
}

package io.github.atengk.oop;

/**
 * 用户实体类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class User {

    private String username;

    private String password;

    public User(String username, String password) {
        this.username = username;
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public String getPassword() {
        return password;
    }
}

package io.github.atengk.oop;

/**
 * 登录服务类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class LoginService {

    public boolean login(User user) {
        return "admin".equals(user.getUsername()) && "123456".equals(user.getPassword());
    }
}

package io.github.atengk.oop;

/**
 * 面向对象登录示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ObjectLoginDemo {

    public static void main(String[] args) {
        User user = new User("admin", "123456");
        LoginService loginService = new LoginService();

        boolean result = loginService.login(user);

        if (result) {
            System.out.println("登录成功");
        } else {
            System.out.println("用户名或密码错误");
        }
    }
}

package io.github.atengk.oop;

/**
 * 封装示例用户类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EncapsulationUser {

    private String username;

    private Integer age;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        if (username == null || username.isBlank()) {
            System.out.println("用户名不能为空");
            return;
        }
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        if (age == null || age < 0 || age > 150) {
            System.out.println("年龄不合法");
            return;
        }
        this.age = age;
    }
}

package io.github.atengk.oop;

/**
 * 动物父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Animal {

    private String name;

    public Animal(String name) {
        this.name = name;
    }

    public void eat() {
        System.out.println(name + "正在吃东西");
    }

    public String getName() {
        return name;
    }
}

package io.github.atengk.oop;

/**
 * 狗子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Dog extends Animal {

    public Dog(String name) {
        super(name);
    }

    public void bark() {
        System.out.println(getName() + "正在叫");
    }
}

package io.github.atengk.oop;

/**
 * 继承测试类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ExtendsDemo {

    public static void main(String[] args) {
        Dog dog = new Dog("旺财");
        dog.eat();
        dog.bark();
    }
}

package io.github.atengk.oop;

/**
 * 多态动物父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PolymorphismAnimal {

    public void sound() {
        System.out.println("动物发出声音");
    }
}

package io.github.atengk.oop;

/**
 * 多态狗子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PolymorphismDog extends PolymorphismAnimal {

    @Override
    public void sound() {
        System.out.println("狗发出汪汪声");
    }
}

package io.github.atengk.oop;

/**
 * 多态猫子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PolymorphismCat extends PolymorphismAnimal {

    @Override
    public void sound() {
        System.out.println("猫发出喵喵声");
    }
}

package io.github.atengk.oop;

/**
 * 多态测试类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PolymorphismDemo {

    public static void main(String[] args) {
        PolymorphismAnimal dog = new PolymorphismDog();
        PolymorphismAnimal cat = new PolymorphismCat();

        dog.sound();
        cat.sound();
    }
}

package io.github.atengk.oop;

/**
 * 用户类，用于演示类的基本定义
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class User {

    private Long id;

    private String username;

    private Integer age;

    public void introduce() {
        System.out.println("用户ID：" + id + "，用户名：" + username + "，年龄：" + age);
    }
}

类名 对象名 = new 类名();

User user = new User();

package io.github.atengk.oop;

/**
 * 用户对象创建示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class UserObjectDemo {

    public static void main(String[] args) {
        User user = new User();
        user.introduce();
    }
}

package io.github.atengk.oop;

/**
 * 多对象创建示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MultiUserDemo {

    public static void main(String[] args) {
        User user1 = new User();
        User user2 = new User();

        user1.introduce();
        user2.introduce();

        System.out.println(user1 == user2);
    }
}

package io.github.atengk.oop;

/**
 * 成员变量默认值示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MemberVariableDemo {

    private int number;

    private boolean enabled;

    private String name;

    public void show() {
        System.out.println("number = " + number);
        System.out.println("enabled = " + enabled);
        System.out.println("name = " + name);
    }

    public static void main(String[] args) {
        MemberVariableDemo demo = new MemberVariableDemo();
        demo.show();
    }
}

访问修饰符 返回值类型 方法名(参数列表) {
    方法体;
}

package io.github.atengk.oop;

/**
 * 商品类，用于演示成员方法
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Product {

    private String name;

    private BigDecimal price;

    private Integer stock;

    public Product(String name, BigDecimal price, Integer stock) {
        this.name = name;
        this.price = price;
        this.stock = stock;
    }

    public void showInfo() {
        System.out.println("商品名称：" + name);
        System.out.println("商品价格：" + price);
        System.out.println("商品库存：" + stock);
    }

    public boolean hasStock() {
        return stock != null && stock > 0;
    }

    public void reduceStock(Integer quantity) {
        if (quantity == null || quantity <= 0) {
            System.out.println("扣减数量必须大于0");
            return;
        }

        if (stock == null || stock < quantity) {
            System.out.println("库存不足");
            return;
        }

        stock -= quantity;
        System.out.println("库存扣减成功，剩余库存：" + stock);
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 商品类，用于演示成员方法
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Product {

    private String name;

    private BigDecimal price;

    private Integer stock;

    public Product(String name, BigDecimal price, Integer stock) {
        this.name = name;
        this.price = price;
        this.stock = stock;
    }

    public void showInfo() {
        System.out.println("商品名称：" + name);
        System.out.println("商品价格：" + price);
        System.out.println("商品库存：" + stock);
    }

    public boolean hasStock() {
        return stock != null && stock > 0;
    }

    public void reduceStock(Integer quantity) {
        if (quantity == null || quantity <= 0) {
            System.out.println("扣减数量必须大于0");
            return;
        }

        if (stock == null || stock < quantity) {
            System.out.println("库存不足");
            return;
        }

        stock -= quantity;
        System.out.println("库存扣减成功，剩余库存：" + stock);
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 商品成员方法调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ProductDemo {

    public static void main(String[] args) {
        Product product = new Product("机械键盘", new BigDecimal("299.00"), 10);

        product.showInfo();

        if (product.hasStock()) {
            product.reduceStock(2);
        }
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 订单类，用于演示构造方法
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Order {

    private String orderNo;

    private BigDecimal amount;

    public Order() {
        System.out.println("无参构造方法被调用");
    }

    public Order(String orderNo, BigDecimal amount) {
        this.orderNo = orderNo;
        this.amount = amount;
        System.out.println("有参构造方法被调用");
    }

    public void showInfo() {
        System.out.println("订单编号：" + orderNo);
        System.out.println("订单金额：" + amount);
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 订单构造方法调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class OrderDemo {

    public static void main(String[] args) {
        Order order1 = new Order();
        order1.showInfo();

        Order order2 = new Order("ORDER_1001", new BigDecimal("199.90"));
        order2.showInfo();
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 不推荐的账户类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class BadAccount {

    public String accountNo;

    public BigDecimal balance;
}

BadAccount account = new BadAccount();
account.balance = new BigDecimal("-1000");

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 银行账户类，用于演示封装
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class BankAccount {

    private String accountNo;

    private BigDecimal balance;

    public BankAccount(String accountNo, BigDecimal balance) {
        if (accountNo == null || accountNo.isBlank()) {
            throw new IllegalArgumentException("账户编号不能为空");
        }
        if (balance == null || balance.compareTo(BigDecimal.ZERO) < 0) {
            throw new IllegalArgumentException("账户余额不能为负数");
        }

        this.accountNo = accountNo;
        this.balance = balance;
    }

    public String getAccountNo() {
        return accountNo;
    }

    public BigDecimal getBalance() {
        return balance;
    }

    public void deposit(BigDecimal amount) {
        if (amount == null || amount.compareTo(BigDecimal.ZERO) <= 0) {
            System.out.println("存款金额必须大于0");
            return;
        }

        balance = balance.add(amount);
        System.out.println("存款成功，当前余额：" + balance);
    }

    public void withdraw(BigDecimal amount) {
        if (amount == null || amount.compareTo(BigDecimal.ZERO) <= 0) {
            System.out.println("取款金额必须大于0");
            return;
        }

        if (balance.compareTo(amount) < 0) {
            System.out.println("余额不足，取款失败");
            return;
        }

        balance = balance.subtract(amount);
        System.out.println("取款成功，当前余额：" + balance);
    }
}

package io.github.atengk.oop;

/**
 * 访问修饰符示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class AccessModifierDemo {

    public String publicValue = "public";

    protected String protectedValue = "protected";

    String defaultValue = "default";

    private String privateValue = "private";

    public void publicMethod() {
        System.out.println("public方法可以被任意位置访问");
    }

    protected void protectedMethod() {
        System.out.println("protected方法可以被同包类或子类访问");
    }

    void defaultMethod() {
        System.out.println("默认方法只能被同包类访问");
    }

    private void privateMethod() {
        System.out.println("private方法只能在当前类内部访问");
    }

    public void showPrivateValue() {
        System.out.println(privateValue);
        privateMethod();
    }
}

package io.github.atengk.oop;

/**
 * 用户资料类，用于演示Getter和Setter
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class UserProfile {

    private String username;

    private Integer age;

    private boolean enabled;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        if (username == null || username.isBlank()) {
            System.out.println("用户名不能为空");
            return;
        }
        this.username = username;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        if (age == null || age < 0 || age > 150) {
            System.out.println("年龄不合法");
            return;
        }
        this.age = age;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }
}

package io.github.atengk.oop;

/**
 * 用户资料Getter和Setter调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class UserProfileDemo {

    public static void main(String[] args) {
        UserProfile userProfile = new UserProfile();

        userProfile.setUsername("ateng");
        userProfile.setAge(20);
        userProfile.setEnabled(true);

        System.out.println("用户名：" + userProfile.getUsername());
        System.out.println("年龄：" + userProfile.getAge());
        System.out.println("是否启用：" + userProfile.isEnabled());
    }
}

package io.github.atengk.oop;

/**
 * this关键字示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ThisUser {

    private String username;

    private Integer age;

    public ThisUser() {
        this("默认用户", 18);
    }

    public ThisUser(String username, Integer age) {
        this.username = username;
        this.age = age;
    }

    public void updateAge(Integer age) {
        this.age = age;
    }

    public void showInfo() {
        this.printLine();
        System.out.println("用户名：" + this.username);
        System.out.println("年龄：" + this.age);
        this.printLine();
    }

    private void printLine() {
        System.out.println("--------------------");
    }
}

package io.github.atengk.oop;

/**
 * this关键字调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ThisUserDemo {

    public static void main(String[] args) {
        ThisUser user1 = new ThisUser();
        user1.showInfo();

        ThisUser user2 = new ThisUser("张三", 22);
        user2.updateAge(23);
        user2.showInfo();
    }
}

public ThisUser(String username, Integer age) {
    username = username;
    age = age;
}

public class 子类 extends 父类 {
    子类自己的成员变量和成员方法;
}

package io.github.atengk.oop;

/**
 * 动物父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Animal {

    private String name;

    public Animal(String name) {
        this.name = name;
    }

    public void eat() {
        System.out.println(name + "正在吃东西");
    }

    public void sleep() {
        System.out.println(name + "正在睡觉");
    }

    public String getName() {
        return name;
    }
}

package io.github.atengk.oop;

/**
 * 狗子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Dog extends Animal {

    public Dog(String name) {
        super(name);
    }

    public void bark() {
        System.out.println(getName() + "正在汪汪叫");
    }
}

package io.github.atengk.oop;

/**
 * 继承调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ExtendsDemo {

    public static void main(String[] args) {
        Dog dog = new Dog("旺财");

        dog.eat();
        dog.sleep();
        dog.bark();
    }
}

public class Dog extends Animal, Pet {
}

package io.github.atengk.oop;

/**
 * 基础动物父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class BaseAnimal {

    public void sound() {
        System.out.println("动物发出声音");
    }
}

package io.github.atengk.oop;

/**
 * 基础狗子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class BaseDog extends BaseAnimal {

    @Override
    public void sound() {
        System.out.println("狗发出汪汪声");
    }
}

package io.github.atengk.oop;

/**
 * 方法重写调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class OverrideDemo {

    public static void main(String[] args) {
        BaseAnimal animal = new BaseAnimal();
        animal.sound();

        BaseDog dog = new BaseDog();
        dog.sound();
    }
}

package io.github.atengk.oop;

/**
 * 父类动物
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ParentAnimal {

    private String name;

    public ParentAnimal(String name) {
        this.name = name;
        System.out.println("父类构造方法执行");
    }

    public void eat() {
        System.out.println(name + "正在吃东西");
    }

    public String getName() {
        return name;
    }
}

package io.github.atengk.oop;

/**
 * 子类狗
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ChildDog extends ParentAnimal {

    public ChildDog(String name) {
        super(name);
        System.out.println("子类构造方法执行");
    }

    public void eat() {
        super.eat();
        System.out.println(getName() + "吃完后摇尾巴");
    }
}

package io.github.atengk.oop;

/**
 * super关键字调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class SuperDemo {

    public static void main(String[] args) {
        ChildDog dog = new ChildDog("旺财");
        dog.eat();
    }
}

package io.github.atengk.oop;

/**
 * 构造方法父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ConstructorParent {

    public ConstructorParent() {
        System.out.println("父类无参构造方法");
    }
}

package io.github.atengk.oop;

/**
 * 构造方法子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ConstructorChild extends ConstructorParent {

    public ConstructorChild() {
        System.out.println("子类无参构造方法");
    }
}

package io.github.atengk.oop;

/**
 * 继承构造方法调用顺序示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ConstructorDemo {

    public static void main(String[] args) {
        ConstructorChild child = new ConstructorChild();
    }
}

package io.github.atengk.oop;

/**
 * 人员父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Person {

    private String name;

    public Person(String name) {
        this.name = name;
        System.out.println("Person有参构造方法");
    }

    public String getName() {
        return name;
    }
}

package io.github.atengk.oop;

/**
 * 教师子类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class Teacher extends Person {

    private String subject;

    public Teacher(String name, String subject) {
        super(name);
        this.subject = subject;
        System.out.println("Teacher有参构造方法");
    }

    public void teach() {
        System.out.println(getName() + "正在教授" + subject);
    }
}

package io.github.atengk.oop;

/**
 * 教师构造方法调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class TeacherDemo {

    public static void main(String[] args) {
        Teacher teacher = new Teacher("李老师", "Java基础");
        teacher.teach();
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付渠道父类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PayChannel {

    public void pay(BigDecimal amount) {
        System.out.println("使用默认支付渠道支付：" + amount + "元");
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付宝支付渠道
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class AliPayChannel extends PayChannel {

    @Override
    public void pay(BigDecimal amount) {
        System.out.println("使用支付宝支付：" + amount + "元");
    }

    public void queryAliPayBill() {
        System.out.println("查询支付宝账单");
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 微信支付渠道
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class WechatPayChannel extends PayChannel {

    @Override
    public void pay(BigDecimal amount) {
        System.out.println("使用微信支付：" + amount + "元");
    }

    public void queryWechatBill() {
        System.out.println("查询微信账单");
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 多态调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PolymorphismDemo {

    public static void main(String[] args) {
        PayChannel aliPay = new AliPayChannel();
        PayChannel wechatPay = new WechatPayChannel();

        aliPay.pay(new BigDecimal("100.00"));
        wechatPay.pay(new BigDecimal("200.00"));
    }
}

父类类型 变量名 = new 子类类型();

PayChannel channel = new AliPayChannel();

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 向上转型示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class UpcastingDemo {

    public static void main(String[] args) {
        PayChannel channel = new AliPayChannel();
        channel.pay(new BigDecimal("99.90"));
    }
}

PayChannel channel = new AliPayChannel();
channel.queryAliPayBill();

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付服务类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PaymentService {

    public void submitPay(PayChannel payChannel, BigDecimal amount) {
        if (payChannel == null) {
            System.out.println("支付渠道不能为空");
            return;
        }

        if (amount == null || amount.compareTo(BigDecimal.ZERO) <= 0) {
            System.out.println("支付金额必须大于0");
            return;
        }

        payChannel.pay(amount);
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付服务调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PaymentServiceDemo {

    public static void main(String[] args) {
        PaymentService paymentService = new PaymentService();

        paymentService.submitPay(new AliPayChannel(), new BigDecimal("88.00"));
        paymentService.submitPay(new WechatPayChannel(), new BigDecimal("66.00"));
    }
}

子类类型 变量名 = (子类类型) 父类引用;

package io.github.atengk.oop;

/**
 * 向下转型示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class DowncastingDemo {

    public static void main(String[] args) {
        PayChannel channel = new AliPayChannel();

        AliPayChannel aliPayChannel = (AliPayChannel) channel;
        aliPayChannel.queryAliPayBill();
    }
}

PayChannel channel = new WechatPayChannel();

AliPayChannel aliPayChannel = (AliPayChannel) channel;
aliPayChannel.queryAliPayBill();

对象 instanceof 类型

package io.github.atengk.oop;

/**
 * instanceof关键字示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class InstanceofDemo {

    public static void main(String[] args) {
        PayChannel channel = new AliPayChannel();

        if (channel instanceof AliPayChannel) {
            AliPayChannel aliPayChannel = (AliPayChannel) channel;
            aliPayChannel.queryAliPayBill();
        } else if (channel instanceof WechatPayChannel) {
            WechatPayChannel wechatPayChannel = (WechatPayChannel) channel;
            wechatPayChannel.queryWechatBill();
        } else {
            System.out.println("未知支付渠道");
        }
    }
}

package io.github.atengk.oop;

/**
 * instanceof模式匹配示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class InstanceofPatternDemo {

    public static void main(String[] args) {
        PayChannel channel = new WechatPayChannel();

        if (channel instanceof AliPayChannel aliPayChannel) {
            aliPayChannel.queryAliPayBill();
        } else if (channel instanceof WechatPayChannel wechatPayChannel) {
            wechatPayChannel.queryWechatBill();
        } else {
            System.out.println("未知支付渠道");
        }
    }
}

public abstract class 类名 {
    普通成员变量;
    普通成员方法;
    抽象方法;
}

package io.github.atengk.oop;

/**
 * 报表导出抽象类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public abstract class AbstractReportExporter {

    private String reportName;

    public AbstractReportExporter(String reportName) {
        this.reportName = reportName;
    }

    public void export(String fileName) {
        if (fileName == null || fileName.isBlank()) {
            System.out.println("导出文件名不能为空");
            return;
        }

        System.out.println("开始导出报表：" + reportName);
        doExport(fileName);
        System.out.println("报表导出完成：" + fileName);
    }

    public String getReportName() {
        return reportName;
    }

    protected abstract void doExport(String fileName);
}

AbstractReportExporter exporter = new AbstractReportExporter("用户报表");

package io.github.atengk.oop;

/**
 * Excel报表导出器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ExcelReportExporter extends AbstractReportExporter {

    public ExcelReportExporter(String reportName) {
        super(reportName);
    }

    @Override
    protected void doExport(String fileName) {
        System.out.println("按照Excel格式导出文件：" + fileName);
    }
}

package io.github.atengk.oop;

/**
 * PDF报表导出器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PdfReportExporter extends AbstractReportExporter {

    public PdfReportExporter(String reportName) {
        super(reportName);
    }

    @Override
    protected void doExport(String fileName) {
        System.out.println("按照PDF格式导出文件：" + fileName);
    }
}

package io.github.atengk.oop;

/**
 * 抽象类调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class AbstractClassDemo {

    public static void main(String[] args) {
        AbstractReportExporter excelExporter = new ExcelReportExporter("用户统计报表");
        AbstractReportExporter pdfExporter = new PdfReportExporter("订单统计报表");

        excelExporter.export("user-report.xlsx");
        pdfExporter.export("order-report.pdf");
    }
}

访问修饰符 abstract 返回值类型 方法名(参数列表);

protected abstract void doExport(String fileName);

public abstract void doExport(String fileName) {
    System.out.println("导出文件");
}

public class ReportExporter {

    public abstract void doExport(String fileName);
}

public void export(String fileName) {
    if (fileName == null || fileName.isBlank()) {
        System.out.println("导出文件名不能为空");
        return;
    }

    System.out.println("开始导出报表：" + reportName);
    doExport(fileName);
    System.out.println("报表导出完成：" + fileName);
}

public interface 接口名 {
    方法声明;
}

package io.github.atengk.oop;

/**
 * 消息发送接口
 *
 * @author Ateng
 * @since 2026-05-15
 */
public interface MessageSender {

    void send(String receiver, String content);
}

MessageSender sender = new MessageSender();

package io.github.atengk.oop;

/**
 * 邮件消息发送器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EmailMessageSender implements MessageSender {

    @Override
    public void send(String receiver, String content) {
        System.out.println("发送邮件给：" + receiver + "，内容：" + content);
    }
}

package io.github.atengk.oop;

/**
 * 短信消息发送器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class SmsMessageSender implements MessageSender {

    @Override
    public void send(String receiver, String content) {
        System.out.println("发送短信给：" + receiver + "，内容：" + content);
    }
}

package io.github.atengk.oop;

/**
 * 接口调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class InterfaceDemo {

    public static void main(String[] args) {
        MessageSender emailSender = new EmailMessageSender();
        MessageSender smsSender = new SmsMessageSender();

        emailSender.send("admin@example.com", "系统运行正常");
        smsSender.send("13800000000", "验证码：123456");
    }
}

void send(String receiver, String content);
public abstract void send(String receiver, String content);

String DEFAULT_ENCODING = "UTF-8";
public static final String DEFAULT_ENCODING = "UTF-8";

package io.github.atengk.oop;

/**
 * 文件存储接口
 *
 * @author Ateng
 * @since 2026-05-15
 */
public interface FileStorage {

    String DEFAULT_BUCKET = "default";

    String upload(String fileName, byte[] content);

    boolean delete(String fileName);
}

package io.github.atengk.oop;

/**
 * 本地文件存储实现类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class LocalFileStorage implements FileStorage {

    @Override
    public String upload(String fileName, byte[] content) {
        if (fileName == null || fileName.isBlank()) {
            return "文件名不能为空";
        }

        if (content == null || content.length == 0) {
            return "文件内容不能为空";
        }

        return "文件已上传到本地存储：" + DEFAULT_BUCKET + "/" + fileName;
    }

    @Override
    public boolean delete(String fileName) {
        if (fileName == null || fileName.isBlank()) {
            System.out.println("文件名不能为空");
            return false;
        }

        System.out.println("删除本地文件：" + fileName);
        return true;
    }
}

public class LocalFileStorage implements FileStorage {
}

package io.github.atengk.oop;

/**
 * 消息格式化接口
 *
 * @author Ateng
 * @since 2026-05-15
 */
public interface MessageFormatter {

    String format(String content);

    default String formatWithPrefix(String content) {
        if (content == null || content.isBlank()) {
            return "[系统消息] 空消息";
        }
        return "[系统消息] " + format(content);
    }

    static boolean isBlank(String content) {
        return content == null || content.isBlank();
    }
}

package io.github.atengk.oop;

/**
 * 文本消息格式化器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class TextMessageFormatter implements MessageFormatter {

    @Override
    public String format(String content) {
        if (MessageFormatter.isBlank(content)) {
            return "空消息";
        }
        return content.trim();
    }
}

package io.github.atengk.oop;

/**
 * 告警消息格式化器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class AlarmMessageFormatter implements MessageFormatter {

    @Override
    public String format(String content) {
        if (MessageFormatter.isBlank(content)) {
            return "空告警";
        }
        return content.trim();
    }

    @Override
    public String formatWithPrefix(String content) {
        return "[告警消息] " + format(content);
    }
}

package io.github.atengk.oop;

/**
 * 接口默认方法和静态方法调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class DefaultStaticMethodDemo {

    public static void main(String[] args) {
        MessageFormatter textFormatter = new TextMessageFormatter();
        MessageFormatter alarmFormatter = new AlarmMessageFormatter();

        System.out.println(textFormatter.formatWithPrefix("服务启动成功"));
        System.out.println(alarmFormatter.formatWithPrefix("CPU使用率过高"));

        System.out.println(MessageFormatter.isBlank(""));
    }
}

public abstract class AbstractEmployee {

    private String name;

    private String employeeNo;

    public abstract BigDecimal calculateSalary();
}

public interface Exportable {

    String export();
}

外部类.内部类 对象名 = 外部类对象.new 内部类();

package io.github.atengk.oop;

/**
 * 成员内部类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MemberInnerClassDemo {

    private String username = "张三";

    public class UserAddress {

        private String city = "重庆";

        public void showAddress() {
            System.out.println(username + "居住在" + city);
        }
    }

    public static void main(String[] args) {
        MemberInnerClassDemo outer = new MemberInnerClassDemo();
        UserAddress address = outer.new UserAddress();

        address.showAddress();
    }
}

外部类.静态内部类 对象名 = new 外部类.静态内部类();

package io.github.atengk.oop;

/**
 * 静态内部类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class StaticInnerClassDemo {

    private static String systemName = "用户管理系统";

    private String username = "李四";

    public static class SystemConfig {

        private String version = "v1.0.0";

        public void showConfig() {
            System.out.println("系统名称：" + systemName);
            System.out.println("系统版本：" + version);
        }
    }

    public static void main(String[] args) {
        StaticInnerClassDemo.SystemConfig config = new StaticInnerClassDemo.SystemConfig();
        config.showConfig();
    }
}

StaticInnerClassDemo outer = new StaticInnerClassDemo();
System.out.println(outer.username);

package io.github.atengk.oop;

/**
 * 局部内部类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class LocalInnerClassDemo {

    public void printUserInfo(String username) {
        String prefix = "用户信息：";

        class UserPrinter {

            public void print() {
                System.out.println(prefix + username);
            }
        }

        UserPrinter printer = new UserPrinter();
        printer.print();
    }

    public static void main(String[] args) {
        LocalInnerClassDemo demo = new LocalInnerClassDemo();
        demo.printUserInfo("王五");
    }
}

public void printUserInfo(String username) {
    username = "赵六";

    class UserPrinter {

        public void print() {
            System.out.println(username);
        }
    }
}

接口或父类 对象名 = new 接口或父类() {
    方法重写;
};

package io.github.atengk.oop;

/**
 * 任务处理接口
 *
 * @author Ateng
 * @since 2026-05-15
 */
public interface TaskHandler {

    void handle(String taskName);
}

package io.github.atengk.oop;

/**
 * 匿名内部类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class AnonymousInnerClassDemo {

    public static void main(String[] args) {
        TaskHandler handler = new TaskHandler() {

            @Override
            public void handle(String taskName) {
                System.out.println("正在处理任务：" + taskName);
            }
        };

        handler.handle("数据同步");
    }
}

TaskHandler handler = taskName -> System.out.println("正在处理任务：" + taskName);
handler.handle("数据同步");

public enum 枚举名 {
    枚举常量1,
    枚举常量2,
    枚举常量3
}

package io.github.atengk.oop;

/**
 * 订单状态枚举
 *
 * @author Ateng
 * @since 2026-05-15
 */
public enum OrderStatus {

    CREATED,

    PAID,

    SHIPPED,

    FINISHED,

    CANCELED
}

package io.github.atengk.oop;

/**
 * 枚举基础使用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EnumBasicDemo {

    public static void main(String[] args) {
        OrderStatus status = OrderStatus.PAID;

        if (status == OrderStatus.PAID) {
            System.out.println("订单已支付，可以安排发货");
        }

        System.out.println("枚举名称：" + status.name());
        System.out.println("枚举序号：" + status.ordinal());
    }
}

package io.github.atengk.oop;

/**
 * 枚举遍历示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EnumValuesDemo {

    public static void main(String[] args) {
        for (OrderStatus status : OrderStatus.values()) {
            System.out.println(status.name() + " -> " + status.ordinal());
        }
    }
}

package io.github.atengk.oop;

/**
 * 支付状态枚举
 *
 * @author Ateng
 * @since 2026-05-15
 */
public enum PayStatus {

    WAIT_PAY(0, "待支付"),

    PAY_SUCCESS(1, "支付成功"),

    PAY_FAILED(2, "支付失败"),

    REFUNDED(3, "已退款");

    private final Integer code;

    private final String description;

    PayStatus(Integer code, String description) {
        this.code = code;
        this.description = description;
    }

    public Integer getCode() {
        return code;
    }

    public String getDescription() {
        return description;
    }

    public static PayStatus getByCode(Integer code) {
        if (code == null) {
            return null;
        }

        for (PayStatus status : PayStatus.values()) {
            if (status.getCode().equals(code)) {
                return status;
            }
        }

        return null;
    }
}

PayStatus status = new PayStatus(1, "支付成功");

package io.github.atengk.oop;

/**
 * 枚举字段和方法调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EnumFieldMethodDemo {

    public static void main(String[] args) {
        PayStatus status = PayStatus.getByCode(1);

        if (status == null) {
            System.out.println("未知支付状态");
            return;
        }

        System.out.println("状态编码：" + status.getCode());
        System.out.println("状态说明：" + status.getDescription());
    }
}

if (payStatus == 1) {
    System.out.println("支付成功");
}

if (payStatus == PayStatus.PAY_SUCCESS.getCode()) {
    System.out.println("支付成功");
}

PayStatus status = PayStatus.PAY_SUCCESS;

if (status == PayStatus.PAY_SUCCESS) {
    System.out.println("支付成功");
}

package io.github.atengk.oop;

/**
 * 订单状态服务示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class OrderStatusService {

    public void handleStatus(OrderStatus status) {
        if (status == null) {
            System.out.println("订单状态不能为空");
            return;
        }

        switch (status) {
            case CREATED:
                System.out.println("订单已创建，等待用户支付");
                break;
            case PAID:
                System.out.println("订单已支付，准备发货");
                break;
            case SHIPPED:
                System.out.println("订单已发货，等待用户收货");
                break;
            case FINISHED:
                System.out.println("订单已完成");
                break;
            case CANCELED:
                System.out.println("订单已取消");
                break;
            default:
                System.out.println("未知订单状态");
                break;
        }
    }
}

package io.github.atengk.oop;

/**
 * 订单状态枚举使用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class OrderStatusDemo {

    public static void main(String[] args) {
        OrderStatusService service = new OrderStatusService();
        service.handleStatus(OrderStatus.PAID);
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 方法重载示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MethodOverloadDemo {

    public BigDecimal calculateAmount(BigDecimal price, Integer quantity) {
        if (price == null || quantity == null) {
            return BigDecimal.ZERO;
        }
        return price.multiply(BigDecimal.valueOf(quantity));
    }

    public BigDecimal calculateAmount(BigDecimal price, Integer quantity, BigDecimal discountAmount) {
        BigDecimal amount = calculateAmount(price, quantity);

        if (discountAmount == null || discountAmount.compareTo(BigDecimal.ZERO) <= 0) {
            return amount;
        }

        return amount.subtract(discountAmount);
    }

    public static void main(String[] args) {
        MethodOverloadDemo demo = new MethodOverloadDemo();

        System.out.println(demo.calculateAmount(new BigDecimal("99.00"), 2));
        System.out.println(demo.calculateAmount(new BigDecimal("99.00"), 2, new BigDecimal("20.00")));
    }
}

package io.github.atengk.oop;

/**
 * 方法重写父类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MethodOverrideParent {

    public void printType() {
        System.out.println("父类类型");
    }
}

package io.github.atengk.oop;

/**
 * 方法重写子类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MethodOverrideChild extends MethodOverrideParent {

    @Override
    public void printType() {
        System.out.println("子类类型");
    }
}

package io.github.atengk.oop;

/**
 * 方法重写调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class MethodOverrideDemo {

    public static void main(String[] args) {
        MethodOverrideParent parent = new MethodOverrideParent();
        MethodOverrideParent child = new MethodOverrideChild();

        parent.printType();
        child.printType();
    }
}

package io.github.atengk.oop;

/**
 * this和super父类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ThisSuperParent {

    protected String name = "父类名称";

    public ThisSuperParent() {
        System.out.println("父类无参构造方法");
    }

    public void printName() {
        System.out.println("父类方法：" + name);
    }
}

package io.github.atengk.oop;

/**
 * this和super子类示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ThisSuperChild extends ThisSuperParent {

    private String name = "子类名称";

    public ThisSuperChild() {
        super();
        System.out.println("子类无参构造方法");
    }

    public void printInfo() {
        System.out.println("this.name = " + this.name);
        System.out.println("super.name = " + super.name);

        this.printName();
        super.printName();
    }

    @Override
    public void printName() {
        System.out.println("子类方法：" + name);
    }
}

package io.github.atengk.oop;

/**
 * this和super调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ThisSuperDemo {

    public static void main(String[] args) {
        ThisSuperChild child = new ThisSuperChild();
        child.printInfo();
    }
}

public ThisSuperChild() {
    this("张三");
    super();
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付能力接口
 *
 * @author Ateng
 * @since 2026-05-15
 */
public interface Payable {

    void pay(BigDecimal amount);
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 银行卡支付实现
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class CardPayable implements Payable {

    @Override
    public void pay(BigDecimal amount) {
        System.out.println("使用银行卡支付：" + amount + "元");
    }
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 支付处理抽象类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public abstract class AbstractPayHandler implements Payable {

    private String channelName;

    public AbstractPayHandler(String channelName) {
        this.channelName = channelName;
    }

    @Override
    public void pay(BigDecimal amount) {
        if (amount == null || amount.compareTo(BigDecimal.ZERO) <= 0) {
            System.out.println("支付金额必须大于0");
            return;
        }

        System.out.println("支付渠道：" + channelName);
        doPay(amount);
    }

    protected abstract void doPay(BigDecimal amount);
}

package io.github.atengk.oop;

import java.math.BigDecimal;

/**
 * 银联支付处理器
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class UnionPayHandler extends AbstractPayHandler {

    public UnionPayHandler() {
        super("银联支付");
    }

    @Override
    protected void doPay(BigDecimal amount) {
        System.out.println("调用银联接口完成支付：" + amount + "元");
    }
}

package io.github.atengk.oop;

/**
 * 基本数据类型比较示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class PrimitiveCompareDemo {

    public static void main(String[] args) {
        int number1 = 100;
        int number2 = 100;

        System.out.println(number1 == number2);
    }
}

package io.github.atengk.oop;

/**
 * 字符串比较示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class StringCompareDemo {

    public static void main(String[] args) {
        String str1 = new String("Java");
        String str2 = new String("Java");

        System.out.println(str1 == str2);
        System.out.println(str1.equals(str2));
    }
}

package io.github.atengk.oop;

/**
 * 用户比较示例类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class CompareUser {

    private Long id;

    private String username;

    public CompareUser(Long id, String username) {
        this.id = id;
        this.username = username;
    }
}

package io.github.atengk.oop;

/**
 * 对象比较示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class ObjectCompareDemo {

    public static void main(String[] args) {
        CompareUser user1 = new CompareUser(1L, "admin");
        CompareUser user2 = new CompareUser(1L, "admin");

        System.out.println(user1 == user2);
        System.out.println(user1.equals(user2));
    }
}

package io.github.atengk.oop;

import java.util.Objects;

/**
 * 重写equals和hashCode的用户类
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EqualsUser {

    private Long id;

    private String username;

    public EqualsUser(Long id, String username) {
        this.id = id;
        this.username = username;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (!(obj instanceof EqualsUser equalsUser)) {
            return false;
        }

        return Objects.equals(id, equalsUser.id)
                && Objects.equals(username, equalsUser.username);
    }

    @Override
    public int hashCode() {
        return Objects.hash(id, username);
    }
}

package io.github.atengk.oop;

/**
 * equals比较调用示例
 *
 * @author Ateng
 * @since 2026-05-15
 */
public class EqualsCompareDemo {

    public static void main(String[] args) {
        EqualsUser user1 = new EqualsUser(1L, "admin");
        EqualsUser user2 = new EqualsUser(1L, "admin");

        System.out.println(user1 == user2);
        System.out.println(user1.equals(user2));
    }
}

String status = null;

if ("SUCCESS".equals(status)) {
    System.out.println("处理成功");
}

String status = null;

if (status.equals("SUCCESS")) {
    System.out.println("处理成功");
}