Java—多态

package com.test;

public class Animal {
    public int age = 1;
    public void eat() {
        System.out.println("动物具有吃东西的能力");
    }
}

package com.test;

public class Cat extends Animal{
    public int age = 2;
    public void eat() {
        System.out.println("兔子吃胡萝卜");
    }
    public void nature() {
        System.out.println("兔子胆小");
    }
}

package com.test;

public class Initail {

    public static void main(String[] args) {
        Animal animal = new Animal();
        Animal cat = new Cat();
        //Cat cat1 = new Animal();错误
        animal.eat();
        cat.eat();
        //cat.nature();错误
    }
}

package com.test;

public class Initail {

    public static void main(String[] args) {
        Dog dog = new Dog();
        Animal animal = dog;//向上类型转换
        
        if (animal instanceof Dog) {
            Dog dog2 = (Dog)animal;
        } else {
            System.out.println("无法转换为Dog类型");
        }
        
        if (animal instanceof Cat) {
            Cat cat = (Cat)animal;
        } else {
            System.out.println("无法转换为Cat类型");
        }
    }
}

package cn.test;

public abstract class Telephone {
    public abstract void call();
    public abstract void sendMsg();
}

package cn.test;

public class Cellphone extends Telephone {
    public void call() {
        System.out.println("用键盘打电话");
    }
    public void sendMsg() {
        System.out.println("用键盘发短信");
    }
}

package cn.test;

public class Smartphone extends Telephone {

    @Override
    public void call() {
        System.out.println("用语音打电话");
    }

    @Override
    public void sendMsg() {
        System.out.println("用语音发短信");
    }

}

package cn.test;

public class Initail {
    public static void main(String[] args) {
        Telephone phone1 = new Cellphone();
        phone1.call();
        Telephone phone2 = new Smartphone();
        phone2.call();
    }
}

package cn.test;

public abstract interface IPlayGame {
    public abstract void playGame();
    public static final int NUM = 12;
}

package cn.test;

public class Psp implements IPlayGame {
    @Override
    public void playGame() {
        System.out.println("游戏机能够打游戏");
    }
}

package cn.test;

public class Initail {
    public static void main(String[] args) {
        IPlayGame iplay2 = new Psp();
        iplay2.playGame();
        System.out.println(Psp.NUM);        
    }
}