java之对象转型

public class TestCasting{
    public static void main(String args[]){
        Animal animal = new Animal("name");
        Cat cat = new Cat("catName","blueColor");
        Dog dog = new Dog("dogName","yellowColor");
        
        System.out.println(animal instanceof Animal);
        System.out.println(cat instanceof Animal);
        System.out.println(dog instanceof Animal);
        //System.out.println(animal instanceof cat);   //error
        
        animal = new Dog("dogAnimal","dogColor");
        System.out.println(animal.name);
        //System.out.println(animal.forColor);  //error
        System.out.println(animal instanceof Animal);
        System.out.println(animal instanceof Dog);
        Dog d1 = (Dog)animal;
        System.out.println(d1.forColor); 
    }
}
class Animal{
    public String name;
    public Animal(String name){     
        this.name = name;
    }
}
class Cat extends Animal{
    public String eyeColor;
    public Cat(String name, String eyeColor){
        super(name);
        this.eyeColor = eyeColor;
    }
}

class Dog extends Animal{
    public String forColor;
    public Dog(String name, String forColor){
        super(name);
        this.forColor = forColor;
    }
}