SCJP 1.6版考題 010

1. import java.util.*;
2. public class Quest{
3.   public static void main(String[] args){
4.     String[] colors =
5.       {"blue","red","green","yellow","orange"};
6.      Arrays.sort(colors);
7.      int s2 = Arrays.binarySearch(colors, "orange");
8.      int s3 = Arrays.binarySearch(colors, "violet");
9.      System.out.print(s2 + "" + s3);
10.   }
11. }


What is the result?

  A. 2-1
  B. 2-4
  C. 2-5
  D. 3-1
  E. 3-4
  F. 3-5
  G. Compilation fails.
  H. An exception is thrown at runtime.

解答

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Ans: C

解說:

字串被排完後是：blue, green, orange, red, yellow 
Arrays.binarySearch傳回鍵值在集合中的位置，orange在陣列索引2上
Arrays.binarySearch若找不到鍵值，傳回值是：(-(insertion point) – 1，
insertion point是該鍵值在集合中的依其大小的插入點，violet應插入在yellow前，其插入點是4，-4-1得-5 
(請參考JDK的說明)