Java 对象转型、动态绑定、接口

//对象转型Casting 
class Animal{
    public String name;
    Animal(String name){
        this.name = name;
    }
}

class Cat extends Animal{
    public String eyesColor;
    Cat(String n, String c){
        super(n);
        eyesColor = c;
    }
}

class Dog extends Animal{
    public String furColor;
    Dog(String n, String c){
        super(n);
        furColor = c;
    }
}

public class Casting{
    public static void main(String[]args){
        Animal a = new Animal("name");
        Cat c = new Cat("catname", "blue");
        Dog d = new Dog("dogname", "black");
        
        System.out.println(a instanceof Animal);
        System.out.println(c instanceof Animal);
        System.out.println(d instanceof Animal);
        System.out.println(a instanceof Cat);
        
        a = new Dog("bigyellow","yellow");
        System.out.println(a.name);
        //System.out.println(a.furColor);    wrong
        System.out.println(a instanceof Animal);
        System.out.println(a instanceof Dog);
        Dog d1 = (Dog)a;
        System.out.println(d1.furColor);
    }
}

abstract class Animal{
    public String name;
    Animal(String name){
        this.name = name;
    }
    
    /*
    public void enjoy(){
        System.out.println("yelling...");
    }
    */
    public abstract void enjoy();
}

class Cat extends Animal{
    private String eyesColor;
    Cat(String n, String c){
        super(n);
        eyesColor = c;
    }
    
    public void enjoy(){
        System.out.println("meow...");
    }
}

class Dog extends Animal{
    private String furColor;
    Dog(String n, String c){
        super(n);
        furColor = c;
    }
    
    public void enjoy(){
        System.out.println("Dog barking...");
    }
}

class Bird extends Animal{
    
    Bird(){
        super("bird");
    }
    
    public void enjoy(){
        System.out.println("bird screaming....");
    }
}

class Lady{
    private String name;
    private Animal pet; //define superclass reference
    
    Lady(String name, Animal pet){
        this.name = name;
        this.pet = pet;
    }
    
    public void myPetEnjoy(){
        pet.enjoy();
    }
}

public class TestPolymorph{
    public static void main(String [] args){
        Cat c = new Cat("catname","blue");
        Dog d = new Dog("dogname", "black");
        Bird b = new Bird();
        Lady L1 = new Lady("L1",c);
        Lady L2 = new Lady("L2",d);
        Lady L3 = new Lady("L3",b);
        L1.myPetEnjoy();
        c.enjoy();
        L2.myPetEnjoy();
        L3.myPetEnjoy();
    }
}