單項選擇題

1. class Pizza { 
2. java.util.ArrayList toppings; 
3. public final void addTopping(String topping) { 
4. toppings.add(topping);
5. } 
6. } 
7. public class PepperoniPizza extends Pizza { 
8. public void addTopping(String topping) { 
9. System.out.println(”Cannot add Toppings”); 
10. } 
11. public static void main(String[] args) { 
12. Pizza pizza = new PepperoniPizza(); 
13. pizza.addTopping(”Mushrooms”); 
14. } 
15. } 
What is the result?() 

A. Compilation fails.
B. Cannot add Toppings
C. The code runs with no output.
D. A NullPointerException is thrown in Line 4.

題目列表

你可能感興趣的試題

微信掃碼免費搜題