OOPS ABAP: Local Interfaces with Example

Interfaces:

•  The ABAP statement “INTERFACE" is used to define the interfaces.
• The ABAP statement “INTERFACES" is used to access the interfaces in a class.
• The interfaces do not have their own implementation sections.
• The symbol "~ (tilt)" is used to refer the attributes of the interfaces. 

Example:

*&---------------------------------------------------------------------*
*& Report ZVB_INTERFACES
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT zvb_interfaces.

PARAMETERS:p_vbeln TYPE vbeln_va.

DATA:it_vbak TYPE ztt_vbak,  "table type
     is_vbak TYPE zst_vbak.  "structure

*Creating interface and method
INTERFACE interface1.
  METHODS display IMPORTING pp_vbeln TYPE vbeln_va
                  EXPORTING pt_vbak  TYPE ztt_vbak.
ENDINTERFACE.

*Creating subclass and calling interface
CLASS subclass1 DEFINITION.
PUBLIC SECTION.
  INTERFACES interface1.
ENDCLASS.

*Implementing the interface method
CLASS subclass1 IMPLEMENTATION.
METHOD interface1~display.
  SELECT vbeln erdat erzet
    FROM vbak
    INTO TABLE pt_vbak
    WHERE vbeln = pp_vbeln.
  ENDMETHOD.
ENDCLASS.

START-OF-SELECTION.
  DATA:lo_obj TYPE REF TO subclass1.
  CREATE OBJECT lo_obj.

*Calling interface method by calling object of subclass
  CALL METHOD lo_obj->interface1~display
    EXPORTING
      pp_vbeln = p_vbeln
    IMPORTING
      pt_vbak  = it_vbak.

  IF it_vbak IS NOT INITIAL.
    LOOP AT it_vbak INTO is_vbak.
      WRITE: / is_vbak-vbeln,
              10 is_vbak-erdat,
              25 is_vbak-erzet.
    ENDLOOP.
  ENDIF.