Nested Interface

 REPORT  znested_test.

TABLES: ekko, ekpo.

SELECTION-SCREEN BEGIN OF BLOCK b1 WITH FRAME TITLE text-001.
SELECT-OPTIONS s_ebeln FOR ekko-ebeln OBLIGATORY.
SELECTION-SCREEN END OF BLOCK b1.

*----------------------------------------------------------------------*
*       INTERFACE it1
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
INTERFACE it1.
  METHODS: mit1, mit2.
ENDINTERFACE.                    "it1

*----------------------------------------------------------------------*
*       INTERFACE it2
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
INTERFACE it2.
  METHODS: mit1, mit2.
  INTERFACES it1.
ENDINTERFACE.                    "it2

*----------------------------------------------------------------------*
*       CLASS cls DEFINITION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS cls DEFINITION.

  PUBLIC SECTION.
    TYPES: BEGIN OF ty_ekko,
            ebeln TYPE ekko-ebeln,
            bukrs TYPE ekko-bukrs,
            lifnr TYPE ekko-lifnr,
           END OF ty_ekko,

           BEGIN OF ty_ekpo,
            ebeln TYPE ekpo-ebeln,
            ebelp TYPE ekpo-ebelp,
            matnr TYPE ekpo-matnr,
            werks TYPE ekpo-werks,
            lgort TYPE ekpo-lgort,
           END OF ty_ekpo,

           BEGIN OF ty_out,
            ebeln TYPE ekpo-ebeln,
            ebelp TYPE ekpo-ebelp,
            matnr TYPE ekpo-matnr,
            werks TYPE ekpo-werks,
            lgort TYPE ekpo-lgort,
            bukrs TYPE ekko-bukrs,
            lifnr TYPE ekko-lifnr,
           END OF ty_out.

    DATA: wa_ekko TYPE ty_ekko,
          wa_ekpo TYPE ty_ekpo,
          wa_out  TYPE ty_out,
          it_ekko TYPE STANDARD TABLE OF ty_ekko,
          it_ekpo TYPE STANDARD TABLE OF ty_ekpo,
          it_out  TYPE STANDARD TABLE OF ty_out.

    INTERFACES it2.

ENDCLASS.                    "cls DEFINITION

*----------------------------------------------------------------------*
*       CLASS cls IMPLEMENTATION
*----------------------------------------------------------------------*
*
*----------------------------------------------------------------------*
CLASS cls IMPLEMENTATION.
  METHOD it1~mit1.

    SELECT ebeln bukrs lifnr FROM ekko INTO TABLE it_ekko
    WHERE ebeln IN s_ebeln.

    IF sy-subrc = 0.
      SORT it_ekko BY ebeln.
    ELSE.
      MESSAGE 'Purchase Order Doesn''t Exist' TYPE 'I'.
      LEAVE LIST-PROCESSING.
    ENDIF.

  ENDMETHOD.                                                "it1~mit1

  METHOD it1~mit2.

    SELECT ebeln ebelp matnr werks lgort
      FROM ekpo INTO TABLE it_ekpo
      FOR ALL ENTRIES IN it_ekko
      WHERE ebeln = it_ekko-ebeln.

    IF sy-subrc = 0.
      SORT it_ekpo BY ebeln ebelp.
    ENDIF.

  ENDMETHOD.                                                "it1~mit2

  METHOD it2~mit1.

    IF it_ekpo IS NOT INITIAL.
      LOOP AT it_ekpo INTO wa_ekpo.
        wa_out-ebeln = wa_ekpo-ebeln.
        wa_out-ebelp = wa_ekpo-ebelp.
        wa_out-matnr = wa_ekpo-matnr.
        wa_out-werks = wa_ekpo-werks.
        wa_out-lgort = wa_ekpo-lgort.

        READ TABLE it_ekko INTO wa_ekko
        WITH KEY ebeln = wa_ekpo-ebeln BINARY SEARCH.
        IF sy-subrc = 0.
          wa_out-bukrs = wa_ekko-bukrs.
          wa_out-lifnr = wa_ekko-lifnr.
        ENDIF.

        APPEND wa_out TO it_out.
        CLEAR: wa_out, wa_ekko, wa_ekpo.
      ENDLOOP.
    ENDIF.

  ENDMETHOD.                                                "it2~mit1

  METHOD it2~mit2.

    IF it_out IS NOT INITIAL.
      LOOP AT it_out INTO wa_out.
        AT FIRST.
          WRITE: / 'Purchase Order',
                18 'Item',
                26 'Material',
                48 'Plant',
                55 'Storage',
                65 'Company',
                75 'Vendor'.
          ULINE.
          SKIP.
        ENDAT.

        WRITE: / wa_out-ebeln,
              18 wa_out-ebelp,
              26 wa_out-matnr,
              48 wa_out-werks,
              55 wa_out-lgort,
              65 wa_out-bukrs,
              75 wa_out-lifnr.
      ENDLOOP.
    ENDIF.

  ENDMETHOD.                                                "it2~mit2
ENDCLASS.                    "cls IMPLEMENTATION

START-OF-SELECTION.
  DATA obj TYPE REF TO cls.
  CREATE OBJECT obj.
  CALL METHOD: obj->it1~mit1,
               obj->it1~mit2,
               obj->it2~mit1,
               obj->it2~mit2.