SCJP題庫第085題

11. class Animal{public String noise(){return "peep";}}
12. class Dog extends Animal{
13.   public String noise(){return "bark";}
14  }
15. class Cat extends Animal{
16.   public String noise(){return "meow";}
17. }
...
30. Animal animal = new Dog();
31. Cat cat = (Cat)animal;
32. System.out.println(cat.noise());
What is the result?


A. peep
B. bark
C. meow
D. Compilation fails.
E. An exception is thrown at runtime.
 
Ans: E
 
解說:
animal 是指向Dog物件,
Cat類別與Dog類別二者間無繼承關係,不可以指向animal 所指向的Dog物件

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