java对象转型实例分析

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;
  }
}