单选题现有:  class Dog{ }  class Harrier extends Dog  { }       class DogTest{   public  static void main (String  []  args) {      Dog dl=new Dog();      Harrier hl=new Harrier();      Dog d2=hl;   Harrier h2=  (Harrier) d2;      Harrier h3=d2;     }      }  下面哪一项是正确的?()A2个Dog对象被创建B2个Harrier对象被创建C3个Harrier对象被创建D编译失败

单选题
现有:  class Dog{ }  class Harrier extends Dog  { }       class DogTest{   public  static void main (String  []  args) {      Dog dl=new Dog();      Harrier hl=new Harrier();      Dog d2=hl;   Harrier h2=  (Harrier) d2;      Harrier h3=d2;     }      }  下面哪一项是正确的?()
A

2个Dog对象被创建

B

2个Harrier对象被创建

C

3个Harrier对象被创建

D

编译失败


参考解析

解析: 暂无解析

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单选题class Animal{ Animal getOne(){return new Animal();}}   class Dog extends Animal{   //insert code here   }   class AnimalTest{   public static void main(String[] args){   Animal[] animal={ new Animal(), new Dog()};   for(Animal a:animal){   Animal x= a.getOne();   }   }   }   和代码:   3a.Dog getOne() { return new Dog();}   3b.Animal getOne() { return new Dog();}   第3行中插入的哪项编译且运行无异常?A3a行或3b行B既非3a,也非3bC3a行D3b行