public static void main(String[] args) { // TODO Auto-generated method stub Dog dog = new Dog(); Cat cat=new Cat(); Animal animal=dog; Animal animal1=cat; if(animal instanceof Dog){ Dog dog2=(Dog)animal; }else{ System.out.println("無法進行類型轉換"); } if(animal instanceof Cat){ Cat cat1=(Cat)animal1; }else{ System.out.println("無法進行類型轉換"); } }}