Java的折半查找程序

  返回值为负则未找到。
    public static int binarySearch(long[] a, long key)
   {
       int low = 0;
       int high = a.length-1;
 
       while (low <= high)
      {
          /** 左移一位等于除以2*/
           int mid = (low + high) >> 1;

           long midVal = a[mid];
 
           if (midVal < key)
              low = mid + 1;
           else if (midVal > key)
              high = mid - 1;
           else
              return mid;
       }
       return -(low + 1); 
    }