想要使用第一个控制器的对象从一个控制器动态创建一个按钮

Question

我想通过创建该控制器的对象来从一个控制器创建一个按钮，但是在将按钮添加到hbox时，我得到一个空指针异常。

这是我的代码：

@FXML
private void AddTable1(ActionEvent event)throws Exception
{       
    List<Button> buttonlist = new ArrayList<Button>(); 
    String sql = "select * from TABLE_NUMBERS";
    ResultSet rs = stmt.executeQuery(sql);
    int id=1;
    while(rs.next())
    {
        id++;

         buttonlist.add(new Button("+tbl_number+"));

    }
    String tbl_type=combo1.getSelectionModel().getSelectedItem();
    String tax = combo2.getSelectionModel().getSelectedItem();
    int tbl_number =Integer.parseInt(table_no.getText())+0;
    System.out.println(tbl_number);
    int max_cap = Integer.parseInt(capa.getText());
    String des=desc.getText(); 
    String sql1 ="INSERT INTO Table_Numbers VALUES("+id+",'"+tbl_type+"',"+tbl_number+","+max_cap+",'"+des+"','"+tax+"'"+")";
    System.out.println(sql1);
    if(!"+table_number+".equals("0"))
    {
          stmt.execute(sql1);
          Alert alert = new Alert(Alert.AlertType.INFORMATION);
          alert.setTitle("TABLE");
          alert.setHeaderText(null);
          alert.setContentText("SUCCESSFULLY UPDATED");
          alert.showAndWait();
     //     Stage stage = (Stage)Add.getScene().getWindow();
     //     stage.close();
    }
      buttonlist.add(new Button("+tbl_number+"));
    for(int i=0;i<buttonlist.size();i++)
    {        
        buttonlist.get(i).setMinWidth(120.0f); 
        buttonlist.get(i).setWrapText(true);
        buttonlist.get(i).setMinHeight(40);    
    } 
    Button button1 = new Button("+tbl_number+");
    RestaurantsController rc=new RestaurantsController();
    System.out.println(buttonlist.size());
    for(int i=0; i<=buttonlist.size();i++)
    {
      rc.hbox.getChildren().addAll(buttonlist.get(0));//null pointer exception
    }
}