Difference between ooabap and java

Question

eventhough both java and ooabap are oops languages there may be some difference between them as c++ and java in using the oops concepts or may be there is an advantage in using ooabap than java .
                                                        any one pls  reply to the above asked question.
<REMOVED BY MODERATOR>
Edited by: rahul nuthi on Feb 26, 2008 1:10 PM
Edited by: Alvaro Tejada Galindo on Feb 26, 2008 11:19 AM

Answer 1

hi
OOPs ABAP uses Classes and Interfaces which uses Methods and events.
If you have Java skills it is advantage for you.
There are Local classes as well as Global Classes.
Local classes we can work in SE38 straight away.
But mostly it is better to use the Global classes.
Global Classes or Interfaces are to be created in SE24.
SAP already given some predefined classes and Interfaces.
This OOPS concepts very useful for writing BADI's also.
So first create a class in SE 24.
Define attributes, Methods for that class.
Define parameters for that Method.
You can define event handlers also to handle the messages.
After creation in each method write the code.
Methods are similar to ABAP PERFORM -FORM statements.
After the creation of CLass and methods come to SE38 and create the program.
In the program create a object type ref to that class and with the help of that Object call the methods of that Class and display the data.
Example:
REPORT sapmz_hf_alv_grid .
Type pool for icons - used in the toolbar
TYPE-POOLS: icon.
TABLES: zsflight.
To allow the declaration of o_event_receiver before the
lcl_event_receiver class is defined, decale it as deferred in the
start of the program
CLASS lcl_event_receiver DEFINITION DEFERRED.
G L O B A L I N T E R N A L T A B L E S
*DATA: gi_sflight TYPE STANDARD TABLE OF sflight.
To include a traffic light and/or color a line the structure of the
table must include fields for the traffic light and/or the color
TYPES: BEGIN OF st_sflight.
INCLUDE STRUCTURE zsflight.
Field for traffic light
TYPES: traffic_light TYPE c.
Field for line color
types: line_color(4) type c.
TYPES: END OF st_sflight.
TYPES: tt_sflight TYPE STANDARD TABLE OF st_sflight.
DATA: gi_sflight TYPE tt_sflight.
G L O B A L D A T A
DATA: ok_code LIKE sy-ucomm,
Work area for internal table
g_wa_sflight TYPE st_sflight,
ALV control: Layout structure
gs_layout TYPE lvc_s_layo.
Declare reference variables to the ALV grid and the container
DATA:
go_grid TYPE REF TO cl_gui_alv_grid,
go_custom_container TYPE REF TO cl_gui_custom_container,
o_event_receiver TYPE REF TO lcl_event_receiver.
DATA:
Work area for screen 200
g_screen200 LIKE zsflight.
Data for storing information about selected rows in the grid
DATA:
Internal table
gi_index_rows TYPE lvc_t_row,
Information about 1 row
g_selected_row LIKE lvc_s_row.
C L A S S E S
CLASS lcl_event_receiver DEFINITION.
PUBLIC SECTION.
METHODS:
handle_toolbar FOR EVENT toolbar OF cl_gui_alv_grid
IMPORTING
e_object e_interactive,
handle_user_command FOR EVENT user_command OF cl_gui_alv_grid
IMPORTING e_ucomm.
ENDCLASS.
CLASS lcl_event_receiver IMPLEMENTATION
CLASS lcl_event_receiver IMPLEMENTATION.
METHOD handle_toolbar.
Event handler method for event toolbar.
CONSTANTS:
Constants for button type
c_button_normal TYPE i VALUE 0,
c_menu_and_default_button TYPE i VALUE 1,
c_menu TYPE i VALUE 2,
c_separator TYPE i VALUE 3,
c_radio_button TYPE i VALUE 4,
c_checkbox TYPE i VALUE 5,
c_menu_entry TYPE i VALUE 6.
DATA:
ls_toolbar TYPE stb_button.
Append seperator to the normal toolbar
CLEAR ls_toolbar.
MOVE c_separator TO ls_toolbar-butn_type..
APPEND ls_toolbar TO e_object->mt_toolbar.
Append a new button that to the toolbar. Use E_OBJECT of
event toolbar. E_OBJECT is of type CL_ALV_EVENT_TOOLBAR_SET.
This class has one attribute MT_TOOLBAR which is of table type
TTB_BUTTON. The structure is STB_BUTTON
CLEAR ls_toolbar.
MOVE 'CHANGE' TO ls_toolbar-function.
MOVE icon_change TO ls_toolbar-icon.
MOVE 'Change flight' TO ls_toolbar-quickinfo.
MOVE 'Change' TO ls_toolbar-text.
MOVE ' ' TO ls_toolbar-disabled.
APPEND ls_toolbar TO e_object->mt_toolbar.
ENDMETHOD.
METHOD handle_user_command.
Handle own functions defined in the toolbar
CASE e_ucomm.
WHEN 'CHANGE'.
PERFORM change_flight.
LEAVE TO SCREEN 0.
ENDCASE.
ENDMETHOD.
ENDCLASS.
S T A R T - O F - S E L E C T I O N.
START-OF-SELECTION.
SET SCREEN '100'.
*& Module USER_COMMAND_0100 INPUT
MODULE user_command_0100 INPUT.
CASE ok_code.
WHEN 'EXIT'.
LEAVE TO SCREEN 0.
ENDCASE.
ENDMODULE. " USER_COMMAND_0100 INPUT
*& Module STATUS_0100 OUTPUT
MODULE status_0100 OUTPUT.
DATA:
For parameter IS_VARIANT that is sued to set up options for storing
the grid layout as a variant in method set_table_for_first_display
l_layout TYPE disvariant,
Utillity field
l_lines TYPE i.
After returning from screen 200 the line that was selected before
going to screen 200, should be selected again. The table gi_index_rows
was the output table from the GET_SELECTED_ROWS method in form
CHANGE_FLIGHT
DESCRIBE TABLE gi_index_rows LINES l_lines.
IF l_lines > 0.
CALL METHOD go_grid->set_selected_rows
EXPORTING
it_index_rows = gi_index_rows.
CALL METHOD cl_gui_cfw=>flush.
REFRESH gi_index_rows.
ENDIF.
Read data and create objects
IF go_custom_container IS INITIAL.
Read data from datbase table
PERFORM get_data.
Create objects for container and ALV grid
CREATE OBJECT go_custom_container
EXPORTING container_name = 'ALV_CONTAINER'.
CREATE OBJECT go_grid
EXPORTING
i_parent = go_custom_container.
Create object for event_receiver class
and set handlers
CREATE OBJECT o_event_receiver.
SET HANDLER o_event_receiver->handle_user_command FOR go_grid.
SET HANDLER o_event_receiver->handle_toolbar FOR go_grid.
Layout (Variant) for ALV grid
l_layout-report = sy-repid. "Layout fo report
Setup the grid layout using a variable of structure lvc_s_layo
Set grid title
gs_layout-grid_title = 'Flights'.
Selection mode - Single row without buttons
(This is the default mode
gs_layout-sel_mode = 'B'.
Name of the exception field (Traffic light field) and the color
field + set the exception and color field of the table
gs_layout-excp_fname = 'TRAFFIC_LIGHT'.
gs_layout-info_fname = 'LINE_COLOR'.
LOOP AT gi_sflight INTO g_wa_sflight.
IF g_wa_sflight-paymentsum < 100000.
Value of traffic light field
g_wa_sflight-traffic_light = '1'.
Value of color field:
C = Color, 6=Color 1=Intesified on, 0: Inverse display off
g_wa_sflight-line_color = 'C610'.
ELSEIF g_wa_sflight-paymentsum => 100000 AND
g_wa_sflight-paymentsum < 1000000.
g_wa_sflight-traffic_light = '2'.
ELSE.
g_wa_sflight-traffic_light = '3'.
ENDIF.
MODIFY gi_sflight FROM g_wa_sflight.
ENDLOOP.
Grid setup for first display
CALL METHOD go_grid->set_table_for_first_display
EXPORTING i_structure_name = 'SFLIGHT'
is_variant = l_layout
i_save = 'A'
is_layout = gs_layout
CHANGING it_outtab = gi_sflight.
End of grid setup
Raise event toolbar to show the modified toolbar
CALL METHOD go_grid->set_toolbar_interactive.
Set focus to the grid. This is not necessary in this
example as there is only one control on the screen
CALL METHOD cl_gui_control=>set_focus EXPORTING control = go_grid.
ENDIF.
ENDMODULE. " STATUS_0100 OUTPUT
*& Module USER_COMMAND_0200 INPUT
MODULE user_command_0200 INPUT.
CASE ok_code.
WHEN 'EXIT200'.
LEAVE TO SCREEN 100.
WHEN'SAVE'.
PERFORM save_changes.
ENDCASE.
ENDMODULE. " USER_COMMAND_0200 INPUT
*& Form get_data
FORM get_data.
Read data from table SFLIGHT
SELECT *
FROM zsflight
INTO TABLE gi_sflight.
ENDFORM. " load_data_into_grid
*& Form change_flight
Reads the contents of the selected row in the grid, ans transfers
the data to screen 200, where it can be changed and saved.
FORM change_flight.
DATA:l_lines TYPE i.
REFRESH gi_index_rows.
CLEAR g_selected_row.
Read index of selected rows
CALL METHOD go_grid->get_selected_rows
IMPORTING
et_index_rows = gi_index_rows.
Check if any row are selected at all. If not
table gi_index_rows will be empty
DESCRIBE TABLE gi_index_rows LINES l_lines.
IF l_lines = 0.
CALL FUNCTION 'POPUP_TO_DISPLAY_TEXT'
EXPORTING
textline1 = 'You must choose a line'.
EXIT.
ENDIF.
Read indexes of selected rows. In this example only one
row can be selected as we are using gs_layout-sel_mode = 'B',
so it is only ncessary to read the first entry in
table gi_index_rows
LOOP AT gi_index_rows INTO g_selected_row.
IF sy-tabix = 1.
READ TABLE gi_sflight INDEX g_selected_row-index INTO g_wa_sflight.
ENDIF.
ENDLOOP.
Transfer data from the selected row to screenm 200 and show
screen 200
CLEAR g_screen200.
MOVE-CORRESPONDING g_wa_sflight TO g_screen200.
LEAVE TO SCREEN '200'.
ENDFORM. " change_flight
*& Form save_changes
Changes made in screen 200 are written to the datbase table
zsflight, and to the grid table gi_sflight, and the grid is
updated with method refresh_table_display to display the changes
FORM save_changes.
DATA: l_traffic_light TYPE c.
Update traffic light field
Update database table
MODIFY zsflight FROM g_screen200.
Update grid table , traffic light field and color field.
Note that it is necessary to use structure g_wa_sflight
for the update, as the screen structure does not have a
traffic light field
MOVE-CORRESPONDING g_screen200 TO g_wa_sflight.
IF g_wa_sflight-paymentsum < 100000.
g_wa_sflight-traffic_light = '1'.
C = Color, 6=Color 1=Intesified on, 0: Inverse display off
g_wa_sflight-line_color = 'C610'.
ELSEIF g_wa_sflight-paymentsum => 100000 AND
g_wa_sflight-paymentsum < 1000000.
g_wa_sflight-traffic_light = '2'.
clear g_wa_sflight-line_color.
ELSE.
g_wa_sflight-traffic_light = '3'.
clear g_wa_sflight-line_color.
ENDIF.
MODIFY gi_sflight INDEX g_selected_row-index FROM g_wa_sflight.
Refresh grid
CALL METHOD go_grid->refresh_table_display.
CALL METHOD cl_gui_cfw=>flush.
LEAVE TO SCREEN '100'.
ENDFORM. " save_changes
chk this blog
/people/vijaybabu.dudla/blog/2006/07/21/topofpage-in-alv-using-clguialvgrid
/message/4447073#4447073 [original link is broken]
Difference between ABAP an OOABAP
http://en.wikipedia.org/wiki/Comparison_of_ABAP_and_Java
hope it will help you
regards
sreelatha gullapalli