146 lines
4.0 KiB
Java
146 lines
4.0 KiB
Java
package day06;
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/**
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* 第 6 天：面向对象（下）—— 继承、多态、接口、抽象类
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* 目标：理解 OOP 三大特性中的"继承"和"多态"
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*
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* 重点：
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* extends —— 单继承：子类拥有父类的属性和方法
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* @Override —— 方法重写：子类用自己的实现覆盖父类方法
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* 抽象类 —— 不能被 new，可以有抽象方法（留给子类实现）
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* 接口 —— 一组行为规范（方法签名），一个类可以实现多个接口
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* 多态 —— 父类引用指向子类对象：Animal a = new Dog();
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*/
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// ==================== 1. 抽象父类 ====================
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abstract class Animal {
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protected String name;
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public Animal(String name) {
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this.name = name;
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}
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public String getName() {
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return name;
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}
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// 抽象方法：没有方法体，子类必须实现
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public abstract String makeSound();
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// 普通方法：有方法体，子类可以继承也可以重写
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public void eat() {
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System.out.println(name + " 正在吃东西。");
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}
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}
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// ==================== 2. 接口 ====================
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interface Pet {
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void play(); // 接口中的方法默认是 public abstract
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String getBreed(); // 品种
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}
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// ==================== 3. 子类 Dog ====================
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class Dog extends Animal implements Pet {
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private String breed; // 品种
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public Dog(String name, String breed) {
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super(name); // 调用父类构造方法（必须放在第一行）
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this.breed = breed;
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}
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@Override
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public String makeSound() {
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return "汪汪汪！";
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}
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@Override
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public void play() {
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System.out.println(name + "（" + breed + "）兴奋地摇着尾巴，接住了飞盘！");
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}
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@Override
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public String getBreed() {
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return breed;
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}
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@Override
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public void eat() {
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System.out.println(name + " 狼吞虎咽地吃着狗粮。");
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}
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}
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// ==================== 4. 子类 Cat ====================
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class Cat extends Animal implements Pet {
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private String breed;
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public Cat(String name, String breed) {
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super(name);
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this.breed = breed;
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}
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@Override
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public String makeSound() {
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return "喵喵喵~";
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}
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@Override
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public void play() {
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System.out.println(name + "（" + breed + "）懒洋洋地拨弄着逗猫棒。");
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}
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@Override
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public String getBreed() {
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return breed;
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}
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@Override
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public void eat() {
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System.out.println(name + " 优雅地小口吃着猫粮。");
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}
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}
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// ==================== 测试类 ====================
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class AnimalTest {
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public static void main(String[] args) {
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System.out.println("========== 动物继承体系演示 ==========\n");
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// 1. 基本使用
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Dog wangcai = new Dog("旺财", "金毛");
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Cat miaomiao = new Cat("咪咪", "英短");
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System.out.println("--- 各自叫 ---");
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System.out.println(wangcai.getName() + "：" + wangcai.makeSound());
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System.out.println(miaomiao.getName() + "：" + miaomiao.makeSound());
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System.out.println("\n--- 各自吃 ---");
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wangcai.eat();
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miaomiao.eat();
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System.out.println("\n--- 各自玩 ---");
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wangcai.play();
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miaomiao.play();
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// 2. ★ 多态：父类引用指向子类对象
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System.out.println("\n--- 多态演示 ---");
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Animal[] zoo = { // Animal 类型的数组
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new Dog("阿黄", "中华田园犬"),
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new Cat("小花", "橘猫"),
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new Dog("小黑", "拉布拉多")
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};
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for (Animal a : zoo) {
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// 运行时决定调用哪个子类的 makeSound（动态绑定）
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System.out.println(a.getName() + "：" + a.makeSound());
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a.eat();
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}
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// 3. 接口引用
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System.out.println("\n--- 接口多态 ---");
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Pet[] pets = { wangcai, miaomiao };
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for (Pet p : pets) {
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System.out.print(p.getBreed() + " -> ");
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p.play();
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}
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}
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}
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