SCJP 1.6版考題 198

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.

解答

---

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() + ", ");
  }
}