alv custom control oop button

https://www.youtube.com/watch?v=mSoLu2lNGtY&list=PLmajIBPiks10AfFiWB-w_xXoTcDFTqKtN&index=4

*&---------------------------------------------------------------------*
*& Report ZJI_OO_ALV
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT ZJI_OO_ALV.

data: obj_ccont type ref to cl_gui_custom_container,
      obj_alv type ref to cl_gui_alv_grid.

call screen 200.
*&---------------------------------------------------------------------*
*& Module STATUS_0200 OUTPUT
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
MODULE status_0200 OUTPUT.
 SET PF-STATUS 'MENU'.
* SET TITLEBAR 'xxx'.

data: it_alv type lvc_t_fcat,
  wa_alv type LINE OF lvc_t_fcat.


data it_mara type table of sflights.




    select * from sflights into TABLE it_mara.

wa_alv-tabname = 'it_mara'.
wa_alv-fieldname = 'carrid'.

APPEND wa_alv to it_alv.
clear wa_alv.

wa_alv-tabname = 'it_mara'.
wa_alv-fieldname = 'CITYFROM'.

APPEND wa_alv to it_alv.
clear wa_alv.

  " create ref for cust cont
  CREATE OBJECT obj_ccont
    EXPORTING
      container_name              = 'CUSTCONT'.

  " create ref for cl gui alv grid
CREATE OBJECT obj_alv
  EXPORTING
    i_parent          =  obj_ccont.

"display alv
CALL METHOD obj_alv->set_table_for_first_display
 EXPORTING
    i_structure_name              = 'SFLIGHTS'
  CHANGING
    it_outtab                     = it_mara
*   it_fieldcatalog               = it_alv
*    it_sort                       =
*    it_filter                     =
.

ENDMODULE.


*&---------------------------------------------------------------------*
*&      Module  USER_COMMAND_0200  INPUT
*&---------------------------------------------------------------------*
*       text
*----------------------------------------------------------------------*
MODULE user_command_0200 INPUT.
data okcode_200 type sy-ucomm.
IF  okcode_200 = 'EXIT'.
  LEAVE PROGRAM.
ENDIF.

ENDMODULE.