public void generateOrdersTree() { clientFacade .getSTreeNodeList(NameLabel.getText()) .stream() .forEach( sTreeNode -> { sTreeNode .getClientOrders() .stream() .forEach( clientOrder -> { Date date = new Date(clientOrder.getData()); SimpleDateFormat df2 = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss"); String dateText = df2.format(date); root.add(new DefaultMutableTreeNode(dateText)); }); }); }