@Override public int numberOfClusters() throws Exception {
  if (m_num_clusters == -1) {
    throw new Exception("Haven't generated any clusters!");
  }
  return m_num_clusters;
}

@ Override public int numberOfClusters ( ) throws Exception { if ( m_num_clusters == - 1 ) { throw new Exception ( "Haven't generated any clusters!" ) ; } return m_num_clusters ; }
returns the number of clusters .
