SCJP啊SCJP。。。

Question

本人小菜鸟。。SCJP考题。
public static 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.print(s2 + "" + s3); 
                    } 
            }
}
为啥s3是-5求高手解释下2分法检索

Answer 1

[code="java"]private static int binarySearch0(Object[] a, int fromIndex, int toIndex,
Object key) {
int low = fromIndex;
int high = toIndex - 1;

while (low <= high) {
    int mid = (low + high) >>> 1;
    Comparable midVal = (Comparable)a[mid];
    int cmp = midVal.compareTo(key);

    if (cmp < 0)
    low = mid + 1;
    else if (cmp > 0)
    high = mid - 1;
    else
    return mid; // key found
}
return -(low + 1);  // key not found.
}

[/code]
人家是这样实现的，最后当然是－5啦