Using Methods in Class

Methods describe the behavior of objects within a class. With the help of methods, the system provides operations, services and functions. Via methods, a user can manipulate the objects in a class or also the class itself. As for attributes, there are instance-dependent as well as class-dependent (static) methods. ABAP Objects differentiate between instance-dependent and class-dependent methods via the ABAP keywords METHODS or CLASS-METHODS used in the definition part.

In order to carry out instance-dependent (or instance-dependent) methods, the calling program needs a specific instance of the class. That is, the calling program must have a defined reference variable that points to a specific instance. Class methods are not instance-dependent. They can be called at any time by a user. To see how the syntax calls the various method types, see the following example.

REPORT  Z_002_METHODS.

TYPES: TY_NAME(50) TYPE C,

       BOOLEAN(1) TYPE C.

CONSTANTS: CO_TRUE TYPE C VALUE 'X',

           CO_FALSE TYPE C VALUE ' '.

*----------------------------------------------------------------

*       CLASS CL_NAME DEFINITION

*----------------------------------------------------------------

CLASS CL_NAME DEFINITION.

  PUBLIC SECTION.

    CLASS-DATA I_COUNT TYPE I.   " Class Dependent Attribute

                        " Will have same value in all objects

    DATA NAME TYPE TY_NAME.      " Instance Dependent Attribute

               " Will have different values in different objects

    CLASS-METHODS IS_CLASS_INITIATED

                    EXPORTING VALUE(RE_BOOL) TYPE BOOLEAN.

    METHODS: SET_NAME IMPORTING VALUE(IM_NAME) TYPE TY_NAME,

             GET_NAME EXPORTING VALUE(EX_NAME) TYPE TY_NAME.

ENDCLASS.                    "CL_NAME DEFINITION

*----------------------------------------------------------------

*       CLASS CL_NAME IMPLEMENTATION

*----------------------------------------------------------------

CLASS CL_NAME IMPLEMENTATION.

  METHOD IS_CLASS_INITIATED.

    IF I_COUNT > 0.

      RE_BOOL = CO_TRUE.

    ELSE.

      RE_BOOL = CO_FALSE.

    ENDIF.

  ENDMETHOD. "IS_CLASS_INITIATED

  METHOD SET_NAME.

    NAME = IM_NAME.

  ENDMETHOD. "SET_NAME

  METHOD GET_NAME.

    EX_NAME = NAME.

  ENDMETHOD. "GET_NAME

ENDCLASS.                    "CL_NAME IMPLEMENTATION

START-OF-SELECTION.

  DATA BOOL TYPE BOOLEAN.

 
" CHECK IF ANY INSTANCE OF THIS CLASS HAS BEEN CREATED BEFORE

  CALL METHOD CL_NAME=>IS_CLASS_INITIATED

    IMPORTING

      RE_BOOL = BOOL.

  IF BOOL = CO_FALSE.

    " CREATE INSTANCE OF THIS CLASS, IF NO INSTANCE EXIST

    DATA: INSTANCE TYPE REF TO CL_NAME,

          NAME TYPE TY_NAME.

    CREATE OBJECT INSTANCE.

    " SET VALUE FOR NAME ATTRIBUTE

    CALL METHOD INSTANCE->SET_NAME

      EXPORTING

        IM_NAME = 'VINOTH'.

    " GET VALUE OF NAME ATTRIBUTE

    CALL METHOD INSTANCE->GET_NAME

      IMPORTING

        EX_NAME = NAME.

    WRITE: / 'NAME : ' , NAME.

    " CLEAR MEMORY OCCUPIED BY OBJECTS

    CLEAR: INSTANCE.

  ENDIF.

Program Output : 002

NAME :  VINOTH