code: public int indexOf(int elem, int index)
    {
  
      if (null == m_map)
        return -1;
  
      for (int i = index; i < m_firstFree; i++)
      {
        int node = m_map[i];
  
        if (node == elem)
          return i;
      }
  
      return -1;
    }
docs: Searches for the first occurence of the given argument,
  beginning the search at index, and testing for equality
  using the equals method.
  
  @param elem Node to look for
  @param index Index of where to start the search
  @return the index of the first occurrence of the object
  argument in this vector at position index or later in the
  vector; returns -1 if the object is not found.