java API------Arrays类binarySearch方法

//摘自ocjp:
import java.util.*;
public class Quest {
public static void main(String[] args) {
String[] colors = {"blue", "red", "green", "yellow", "orange"};
Arrays.sort(colors);
int s2 = Arrays.binarySearch(colors, "orange");
int s3 = Arrays.binarySearch(colors, "violet");
System.out.println(s2 + " " + s3);
}
}
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.
Answer: C

分析：

Arrays.binarySearch用法：若查找到，则返回key的位置；若未找到，则反回“-插入点”。（例中s3，若向colors中插入“violet”则下标为5）。