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

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