SCJP 1.6版考題 196

Given:
34. HashMap props = new HashMap();
35. props.put("key45", "some value");
36. props.put("keyl2", "some other value");
37. props.put("key39", "yet another value");
38. Set s = props.keySet();
39. //insert code here

What inserted at line 39, will sort the keys in the props HashMap?

 A. Arrays.sort(s);
 B. s = new TreeSet(s);
 C. Collections.sort(s);
 D. s = new SortedSet(s);

解答

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Ans: B

解說: TreeSet是一個排序樹