OOPS ABAP: Usual ABAP Class(Local Class Creation using Instance Method)

Usual ABAP Class

Class : Class is a collection of objects(Methods, Attributes, Events, Interfaces)

Object: An instance of class is known as object

Types of Classes:

1.Global Class 

The T-code 'SE24' is used to create Global Classes. They can be reusable.

a)Usual ABAP Class  --- The purpose of this class is to write the logic.

b)Exception Class --- The purpose of this class is to to raise and handle the exception.

c)Persistence Class --- The purpose of this class is to perform the database operations(Insert,Update,Delete)

d)Unit Test Class --- The purpose of this class is to write unit test cases.

2.Local Class

Local classes are created in program and cannot be reusable.

Class Definition : Declaration part

Class Implementation : Logic

Types of Methods:

a)Instance Method:Instance methods are called by creating object.They are called using (->).

keyword: class.

b)Static Method: Object creation is not needed to call static methods. They are called using(=>).

keyword : class-methods.

Visibility Control :

a)Public : Can be accessed with in the class, with in the sub classes, Outside of the class.

b)Private: Can be accessed with in the class.

c)Protected: Can be accessed with in the class, with in the subclass, not outside the class.

Types of parameters in class methods:

a)Importing -- Input

b)Exporting -- Output

c) Changing -- Input/Output

d)Returning -- A method have any no.of Exporting and Changing parameters, but returning is always one.

Declaration and creation of Object

DATA : LO_OBJECT TYPE REF TO ZCLS_TEST.

CREATE OBJECT LO_OBJECT.

Example on Local Classes:

REPORT zvb_local_cls.

TYPES: BEGIN OF ty_vbak,
         vbeln TYPE vbak-vbeln,
         erdat TYPE vbak-erdat,
         erzet TYPE vbak-erzet,
       END OF ty_vbak,
       BEGIN OF ty_vbap,
         vbeln TYPE vbap-vbeln,
         posnr TYPE vbap-posnr,
       END OF ty_vbap,
       BEGIN OF ty_final,
         vbeln TYPE vbak-vbeln,
         erdat TYPE vbak-erdat,
         erzet TYPE vbak-erzet,
         posnr TYPE vbap-posnr,
       END OF ty_final.

DATA:it_vbak  TYPE TABLE OF ty_vbak,
     is_vbak  TYPE ty_vbak,
     it_vbap  TYPE TABLE OF ty_vbap,
     is_vbap  TYPE ty_vbap,
     it_final TYPE TABLE OF ty_final,
     is_final TYPE ty_final.

PARAMETERS : p_vbeln TYPE vbak-vbeln.

CLASS class1 DEFINITION.
  PUBLIC SECTION.
    METHODS display IMPORTING p_vbeln  TYPE vbeln_va
                    EXPORTING it_final TYPE ztt_so.
ENDCLASS.
CLASS class1 IMPLEMENTATION.
  METHOD display.
    SELECT vbeln erdat erzet
      FROM vbak
      INTO TABLE it_vbak
      WHERE vbeln = p_vbeln.

    IF it_vbak IS NOT INITIAL.
      SELECT vbeln posnr
        FROM vbap
        INTO TABLE it_vbap
        FOR ALL ENTRIES IN it_vbak
        WHERE vbeln = it_vbak-vbeln.
    ENDIF.

    LOOP AT it_vbap INTO is_vbap.
      is_final-vbeln = is_vbap-vbeln.
      is_final-posnr = is_vbap-posnr.
      READ TABLE it_vbak INTO is_vbak WITH KEY vbeln = is_vbap-vbeln.
      is_final-erdat = is_vbak-erdat.
      is_final-erzet = is_vbak-erzet.
      APPEND is_final TO it_final.
    ENDLOOP.
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
  DATA:lo_object TYPE REF TO class1.
  CREATE OBJECT lo_object.
  CALL METHOD lo_object->display
    EXPORTING
      p_vbeln  = p_vbeln
    IMPORTING
      it_final = it_final.

  IF it_final IS NOT INITIAL.
    LOOP AT it_final INTO is_final.
      WRITE: / is_final-vbeln,
       10 is_final-posnr,
       30 is_final-erdat,
       50 is_final-erzet.
    ENDLOOP.
  ENDIF.