public void addNode(PrintDataElement node){
  if (node == null)   throw new IllegalArgumentException("Node cannot be null");
  if (m_nodes == null)   addRow(false,0);
  m_nodes.add(node);
}

public void addNode ( PrintDataElement node ) { if ( node == null ) throw new IllegalArgumentException ( "Node cannot be null" ) ; if ( m_nodes == null ) addRow ( false , 0 ) ; m_nodes . add ( node ) ; }
add node to data structure row
