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?
1. class Animal { Animal getOne() { return new Animal(); } } 2. class Dog extends Animal { 3. // insert code here 4. } 5. 6. class AnimalTest { 7. public static void main(String [] args) { 8. Animal [] animal = { new Animal(), new Dog() } ; 9. for( Animal a : animal) { 10. Animal x = a.getOne(); 11. } 12. } 13. } 和代码: 3a. Dog getOne() { return new Dog(); } 3b. Animal getOne() { return new Dog(); } 第 3 行中插入的哪项将编译且运行无异常?()