What r the events in alv's

Question

what r the events contain in alv's
plz give in an order
clearly with decsription

Answer 1

(Build up events table)
build an event table, which are used for firing both user commands and the system dependent events i.e. top of page, end of page etc.
A list of possible events is populated into an event table (I_EVENTS) when this table is passed from the function module REUSE_ALV_EVENT_NAMES_GET. The return table from this function module contains all the possible events.
The function module contains following import and export parameters.
IMPORTING PARAMETERS: I_LIST_TYPE
This parameter has possible values from 0-4.
The parameter I_LIST_TYPE is of TYPE SLIS_LIST_TYPE and is DEFAULT 0 .
EXPORTING PARAMETERS:  I_EVENTS table.
This table is of TYPE SLIS_T_EVENT and returns to the program the name of all the possible events.
The table structure contains the fields:
     I_EVENTS-NAME: Name of the Callback event.
I_EVENTS-FORM: Name of the form routine that should be called in the calling program at the event.
Only events with a form routine name are processed.
The I_EVENTS table returns with the following possible constants:
1.     Slis_ev_item_data_expand TYPE slis_formname VALUE 'ITEM_DATA_EXPAND'.     
Only relevant for hierarchical-sequential lists using the layout parameter IS_LAYOUT-EXPAND_FIELDNAME of the structure IS_LAYOUT. Exit for passing item entries (ITEM table) for a header record that was expanded interactively by the user.
2.     Slis_ev_reprep_sel_modify TYPE slis_formname VALUE 'REPREP_SEL_MODIFY'.
RS_SELFIELD-TABINDEX contains the header table index for which the item entries are to       be put in the global item output table (T_OUTTAB_SLAVE). The Callback is only called if ALV has no items for a header that is to be expanded.
RFLG_ALL is passed with 'X' if the user shows all items. The application must ensure that    entries are not repeated in the item table.
    RS_SELFIELD is initial in this case.         
3.     Slis_ev_caller_exit_at_start TYPE slis_formname VALUE 'CALLER_EXIT'.
Is called at the beginning of the function module to make special settings. It is not usually used.          
4.     Slis_ev_user_command TYPE slis_formname VALUE 'USER_COMMAND'.
As this is a frequently-used Callback event, the form routine can also be passed        directly in the interface by passing the user command in the IMPORTING parameter           I_CALLBACK_USER_COMMAND.
5.     Slis_ev_top_of_page TYPE slis_formname VALUE 'TOP_OF_PAGE'.
   Equivalent to the list processing TOP-OF-PAGE event.           
6.     Slis_ev_top_of_coverpage TYPE slis_formname VALUE 'TOP_OF_COVERPAGE'.       
The selection information and list status are output together (if they exist) on a separate page by default
7.     Slis_ev_end_of_coverpage TYPE slis_formname VALUE 'END_OF_COVERPAGE'.       
Analogously to TOP_OF_COVERPAGE the user can add other information
to the information output by ALV (selection information, list status) at this event.
8.     Slis_ev_foreign_top_of_page TYPE slis_formname VALUE ‘FOREIGN_TOP_OF_PAGE'.
The Top-of-page event is always processed in ALV and is only passed to the caller via the Callback mechanism. This is still the case if the caller, e.g. by a user action, processes a branch list which was not formatted by ALV (e.g. a popup with additional information about the list record selected and displayed by ALV).
In this case, top-of-page cannot be formatted by ALV analogously to the basic list, it must be handled completely by the caller. The event top-of-page still occurs in ALV. When ALV notices a top-of-page which was not caused by an ALV output, the form routine in FOREIGN_TOP_OF_PAGE is called.
9.     Slis_ev_foreign_end_of_page TYPE slis_formname VALUE 'FOREIGN_END_OF_PAGE'.  
The event end-of-page is always processed in ALV and only passed to the caller via callback. This is still the case, e.g. when the caller processes a details list which was not formatted by ALV (e.g. a popup with further information about selected list records which were displayed by ALV).
In this case, end-of-page cannot be formatted by ALV analogously to the basic list, it must be handled completely by the caller. The event end-of-page still occurs in ALV. When ALV notices an end-of-page that was not caused by an ALV output, the form routine in FOREIGN_END_OF_PAGE is called.                             
10.     Slis_ev_pf_status_set TYPE slis_formname VALUE 'PF_STATUS_SET'.
If a user list status is to be set, it must be done in the form routine assigned to this event. The ALV function codes, which must not be active, are in the Parameter RT_EXTAB. This table must be passed with the SET PF-STATUS command (with inactive user function codes as well, if necessary).
The STANDARD status of the function group SALV should be used as a          template for a user-specific status. As this is a frequently used Callback event, its form routine can also be passed directly in the interface in the IMPORTING parameter I_CALLBACK_PF_STATUS_SET.
11.     Slis_ev_list_modify TYPE slis_formname VALUE 'LIST_MODIFY'.     
LIST_MODIFY USING R_TABNAME TYPE SLIS_TABNAME
                                         R_INDEX LIKE SY-TABIX
                                         R_INDEX_ITEM LIKE SY-TABIX
                                         R_INDEX_SUM LIKE SY-TABIX.
12.     Slis_ev_top_of_list TYPE slis_formname VALUE 'TOP_OF_LIST'.  
Information output at the start of the list     
13.     Slis_ev_end_of_page TYPE slis_formname VALUE 'END_OF_PAGE'.
Information output at the end of a page. This is only called for printing.
14.     Slis_ev_end_of_list TYPE slis_formname VALUE 'END_OF_LIST'.     
Information output at the end of the list
15.     Slis_ev_after_line_output TYPE slis_formname VALUE 'AFTER_LINE_OUTPUT'.
Output information after each output line. Should only be used in justified cases because it costs a lot of performance.
16.     Slis_ev_before_line_output TYPE slis_formname VALUE   'BEFORE_LINE_OUTPUT'.       
Output information before each output line. Should only be used in justified cases because it costs a lot of performance.         
17.     Slis_ev_subtotal_text TYPE slis_formname VALUE  'SUBTOTAL_TEXT'.                        
This event table (I_EVENTS) is now checked with the desired constants. If the desired constant is found, then the corresponding field for the FORM NAME is populated with the name of the routine containing the corresponding event.
Sample code :
FORMNAME_TOP_OF_PAGE TYPE SLIS_FORMNAME VALUE 'TOP_OF_PAGE',
FORMNAME_END_OF_PAGE TYPE SLIS_FORMNAME VALUE 'END_OF_PAGE', FORMNAME_USER_COMMAND TYPE SLIS_FORMNAME VALUE 'USER_COMMAND'.
DATA: L_I_EVENT TYPE SLIS_ALV_EVENT.
  CALL FUNCTION 'REUSE_ALV_EVENTS_GET'
       EXPORTING
           I_LIST_TYPE = 0
       IMPORTING
            ET_EVENTS   = I_EVENTS.
  READ TABLE I_EVENTS WITH KEY NAME = SLIS_EV_TOP_OF_PAGE
                           INTO L_I_EVENT.
  IF SY-SUBRC = 0.
    MOVE FORMNAME_TOP_OF_PAGE TO L_I_EVENT-FORM.
    APPEND L_I_EVENT TO I_EVENTS.
  ENDIF.
  READ TABLE I_EVENTS WITH KEY NAME = SLIS_EV_END_OF_PAGE
                           INTO L_I_EVENT.
  IF SY-SUBRC = 0.
    MOVE FORMNAME_END_OF_PAGE TO L_I_EVENT-FORM.
    APPEND L_I_EVENT TO I_EVENTS.
  ENDIF.
  CLEAR L_I_EVENT.
  READ TABLE I_EVENTS WITH KEY NAME = SLIS_EV_USER_COMMAND
                           INTO L_I_EVENT.
  IF SY-SUBRC = 0.
    MOVE FORMNAME_USER_COMMAND TO L_I_EVENT-FORM.
    APPEND L_I_EVENT TO I_EVENTS.
  ENDIF.
This will prepare the events table for the report.
The report will contain three forms for the above events:
1.     FORM TOP_OF_PAGE: This form will contain the top of page event for the report i.e. header etc
Using the function module ‘REUSE_ALV_COMMENTARY_WRITE’, the internal table containing the headings for top of page event can be passed to the list output. Also, any logo specific to the report can be passed to the function module.
2.     FORM END_OF_PAGE: This form will contain the end of page event for the report i.e. footer etc
3.     FORM USER_COMMAND: This form will contain the desired user command i.e. pick/line selection
hope this helps
Regards
Abdullah