ABAP - Sample Program On Use Of Public, Private, Protected Classes - OOPS Concept.

Dump of the program:-
REPORT YSUBDEL LINE-SIZE 120.

CLASS parentclass DEFINITION .
PUBLIC SECTION.
DATA : commondata(30) type c value 'Accessible to all'.
METHODS : SHOWVAL.
PROTECTED SECTION.
DATA : protectdata(40) type c value 'Protected data'.
private section.
data : privatedata(30) type c value 'Private data'.
ENDCLASS.

CLASS parentclass IMPLEMENTATION.
METHOD : SHOWVAL.
write:/5 'All data from parentclass shown:-'.
write:/ sy-uline.
WRITE:/5 COMMONDATA,
/5 PROTECTDATA,
/5 PRIVATEDATA.
endmethod.
endclass.

CLASS childclass DEFINITION INHERITING FROM parentclass.
PUBLIC SECTION .
METHODS : subval.
ENDCLASS.

CLASS childclass IMPLEMENTATION.
method : subval.
skip 1.
write:/5 'Data of parent shown from child-'.
write:/5 sy-uline.
WRITE:/5 COMMONDATA,
/5 PROTECTDATA.
Commondata = 'Public data changed in subclass'.
Protectdata = 'Protected data changed in subclass'.
write:/5 sy-uline.
WRITE:/5 COMMONDATA,
/5 PROTECTDATA.
endmethod.
endclass.

START-OF-SELECTION.
DATA : parent type ref to parentclass ,
child type ref to childclass .
create object : parent ,
child .
call method : parent->showval ,
child->subval.
skip 2.
parent->commondata = ‘User changing public data’.
write:/5 parent->commondata.