Displaying ALV on the Selection Screen

REPORT zalv_sel_screen .

TABLES: mara.

DATA: BEGIN OF i_alv OCCURS 0,
     matnr TYPE mara-matnr,
     mtart TYPE mara-mtart,
     matkl TYPE mara-matkl,
     groes TYPE mara-groes,
     maktx TYPE makt-maktx,
     END OF i_alv.

DATA: alv_container  TYPE REF TO cl_gui_docking_container.
DATA: alv_grid       TYPE REF TO cl_gui_alv_grid.
DATA: layout    TYPE lvc_s_layo.
DATA: fieldcat  TYPE lvc_t_fcat.

PARAMETERS: p_check.

INITIALIZATION.

  PERFORM get_data.

AT SELECTION-SCREEN OUTPUT.

  DATA: variant TYPE  disvariant.
 DATA: repid TYPE sy-repid.

  repid = sy-repid.

  variant-report = sy-repid.
 variant-username = sy-uname.

  layout-zebra = 'X'.
 layout-edit_mode = 'X'.

  CHECK alv_container IS INITIAL.

  CREATE OBJECT alv_container
             EXPORTING repid     = repid
                       dynnr     = sy-dynnr
                       side      = alv_container->dock_at_left
                       extension = 1500.

  CREATE OBJECT alv_grid
        EXPORTING
              i_parent          =  alv_container.

*  ALV Specific. Data selection.
*  Populate Field Catalog
 PERFORM get_fieldcatalog.

  CALL METHOD alv_grid->set_table_for_first_display
   EXPORTING
     is_layout        = layout
     is_variant       = variant
     i_save           = 'U'
     i_structure_name = 'I_ALV'
   CHANGING
     it_outtab        = i_alv[]
     it_fieldcatalog  = fieldcat[].

START-OF-SELECTION.

*************************************************************
* FORM GET_DATA
*************************************************************
FORM get_data.

  SELECT * INTO CORRESPONDING FIELDS OF TABLE i_alv
       FROM mara
         INNER JOIN makt
           ON mara~matnr = makt~matnr
                  UP TO 100 ROWS
              WHERE makt~spras = sy-langu.

  SORT i_alv ASCENDING BY matnr.

ENDFORM.                    "get_data

***************************************************************
*      Form  Get_Fieldcatalog - Set Up Columns/Headers
****************************************************************
FORM get_fieldcatalog.

  DATA: ls_fcat TYPE lvc_s_fcat.
 REFRESH: fieldcat.

  CLEAR: ls_fcat.
 ls_fcat-reptext    = 'Material Number'.
 ls_fcat-fieldname  = 'MATNR'.
 ls_fcat-ref_table  = 'I_ALV'.
 ls_fcat-outputlen  = '18'.
 ls_fcat-fix_column = 'X'.
 ls_fcat-key        = 'X'.
 ls_fcat-col_pos    = '1'.
 APPEND ls_fcat TO fieldcat.

  CLEAR: ls_fcat.
 ls_fcat-reptext    = 'Material Type'.
 ls_fcat-fieldname  = 'MTART'.
 ls_fcat-ref_table  = 'I_ALV'.
 ls_fcat-outputlen  = '10'.
 ls_fcat-fix_column = 'X'.
 ls_fcat-key        = 'X'.
 ls_fcat-col_pos    = '2'.
 APPEND ls_fcat TO fieldcat.

  CLEAR: ls_fcat.
 ls_fcat-reptext    = 'Material Group'.
 ls_fcat-fieldname  = 'MATKL'.
 ls_fcat-ref_table  = 'I_ALV'.
 ls_fcat-outputlen  = '12'.
 ls_fcat-col_pos    = '3'.
 APPEND ls_fcat TO fieldcat.

  CLEAR: ls_fcat.
 ls_fcat-reptext    = 'Size'.
 ls_fcat-fieldname  = 'GROES'.
 ls_fcat-ref_table  = 'I_ALV'.
 ls_fcat-outputlen  = '30'.

  ls_fcat-col_pos    = '4'.
 APPEND ls_fcat TO fieldcat.

  CLEAR: ls_fcat.
 ls_fcat-reptext    = 'Material Description'.
 ls_fcat-fieldname  = 'MAKTX'.
 ls_fcat-ref_table  = 'I_ALV'.
 ls_fcat-outputlen  = '40'.

  ls_fcat-col_pos    = '5'.
 APPEND ls_fcat TO fieldcat.

ENDFORM.                    "get_fieldcatalog

Output: