Hello Manish,
this is my source code of singleton class , please have a look
class ZSINGLETON definition
public
create private .
public section.
data NUM1 type I value 23. "#EC NOTEXT .
class-methods GET_INSTANCE_OF
returning
value(OBJ) type ref to ZSINGLETON .
protected section.
private section.
class-data GREF_OBJ type ref to ZSINGLETON .
methods CONSTRUCTOR .
ENDCLASS.
CLASS ZSINGLETON IMPLEMENTATION.
* <SIGNATURE>---------------------------------------------------------------------------------------+
* | Instance Private Method ZSINGLETON->CONSTRUCTOR
* +-------------------------------------------------------------------------------------------------+
* +--------------------------------------------------------------------------------------</SIGNATURE>
method CONSTRUCTOR.
endmethod.
* <SIGNATURE>---------------------------------------------------------------------------------------+
* | Static Public Method ZSINGLETON=>GET_INSTANCE_OF
* +-------------------------------------------------------------------------------------------------+
* | [<-()] OBJ TYPE REF TO ZSINGLETON
* +--------------------------------------------------------------------------------------</SIGNATURE>
METHOD get_instance_of.
IF gref_obj IS NOT BOUND.
CREATE OBJECT gref_obj.
obj = gref_obj.
ELSE.
obj = gref_obj.
ENDIF.
ENDMETHOD.
ENDCLASS.