[ABAP] ALV column header

DATA: o_salv TYPE REF TO cl_salv_table.

cl_salv_table=>factory( IMPORTING r_salv_table = o_salv
                        CHANGING  t_table      = l_lines ).

LOOP AT o_salv->get_columns( )->get( ) REFERENCE INTO DATA(l_column).
  DATA(lo_column) = CAST cl_salv_column( l_column->r_column ).
  lo_column->set_fixed_header_text( 'L' ).
ENDLOOP.

o_salv->get_columns( )->get_column( 'TEST1' )->set_long_text( 'Test1 Header' ).
o_salv->get_columns( )->get_column( 'TEST2' )->set_long_text( 'Test2 Header' ).

[ABAP] Select-Option for ALV Layout

Create a ALV Layout Variant
Select-Option for Layout Variant on Selectionscreen
SELECTION-SCREEN BEGIN OF BLOCK b3 WITH FRAME TITLE text-b03.
PARAMETERS: p_vari TYPE slis_vari.
SELECTION-SCREEN END OF BLOCK b3.

INITIALIZATION.

  "Load default layout
  DATA: ls_layout TYPE salv_s_layout_info,
        ls_key    TYPE salv_s_layout_key.

  ls_key-report = sy-repid.

  ls_layout = cl_salv_layout_service=>get_default_layout( s_key    = ls_key
                                                          restrict = '1' ).
  p_vari = ls_layout-layout.

AT SELECTION-SCREEN ON VALUE-REQUEST FOR p_vari.

  "Value Help
  DATA: ls_layout TYPE salv_s_layout_info,
        ls_key    TYPE salv_s_layout_key.

  ls_key-report = sy-repid.

  ls_layout = cl_salv_layout_service=>f4_layouts( s_key    = ls_key
                                                  restrict = '1' ).
  p_vari = ls_layout-layout.

[ABAP] SALV

    TRY.
        cl_salv_table=>factory( IMPORTING r_salv_table = DATA(alv_table)
                                CHANGING  t_table      = lt_display_data ).
        alv_table->display( ).

      CATCH cx_salv_msg.
    ENDTRY.