SCJP題庫第198題

 

Given:

11. public static Iterator reverse(List list){

12.   Collections.reverse(list);

13.   return list.iterator();

14. }

15. public static void main(String[] args){

16.   List list= new ArrayList();

17.   list.add("1"); list.add("2"); list.add("3");

18.   for(Object obj : reverse(list))

19.     System.out.print(obj + ", ");

20. }

What is the result?

A. 3, 2, 1,

B. 1, 2, 3,

C. Compilation fails.

D. The code runs with no output.

E. An exception is thrown at runtime.

 

Ans: C

 

解說:

Iterator不能用enhanced for，要用一般的for

import java.util.*;

class test{

  public static Iterator reverse(List list){

     Collections.reverse(list);

     return list.iterator();

 }

 public static void main(String[] args){

   List<String> list= new ArrayList<String>();

   list.add("1"); list.add("2"); list.add("3");

  Iterator it = reverse(list);

   for(;it.hasNext();)

     System.out.print(it.next().toString() + ", ");

  }

}