topic Re: interfaces. in Application Development and Automation Discussions

interfaces.

Former Member — Fri, 29 Jun 2007 04:43:24 GMT

HI,

what is mean by interfaces oops ? explain in detail.Give some example

Thank you

Ashok kumar

Re: interfaces.

Former Member — Fri, 29 Jun 2007 04:47:29 GMT

hi,

for interfaces

http://help.sap.com/saphelp_47x200/helpdata/en/c3/225b6254f411d194a60000e8353423/content.htm

Interfaces are independent structures that allow you to enhance the class-specific public points of contact by implementing them in classes.

Interfaces can be defined globally in the R/3 repository or locally in ABAP program

Can define exactly same components in Interfaces as in Classes

Unlike classes, Interfaces do not have instances, instead they are implemented by classes

Implemented using INTERFACES statement in the declaration part of the class

INTERFACES statement must be included in the PUBLIC SECTION of the class

Different classes that implement the same interface can all be addressed in the same way.

Interface references allow users to address different classes in the same manner.

Interfaces can also be nested.

Interfaces are the basis for polymorphism in classes, because they allow a single interface method to behave differently in different classes.

If an interface is implemented in the class, the interface components are added in the public section of the class.

A component comp of an interface intf, implemented in a class, becomes a fully-fledged member of that class, with the name intf~comp.

Classes that implement interfaces must implement all of their methods.

METHOD intf~meth.

…

ENDMETHOD.

Interfaces allow you to use different classes in a uniform way (polymorphism).

Interface References :

Creating Interface Reference Variables

DATA obj TYPE REF TO intf.

Using this reference variable, you can access any of the components defined in the interface

Nested Interfaces

Interface can include one or more interfaces as components, which can contain interfaces themselves.

Compound Interface : It includes other interface as its component.

Elementary Interface : It does not include any interface as a component.

All interface components of a compound interface have the same level

A component interface exists only once even if it is used once more as a component of another component interface.

Aliases : It can be used to assign alias names to the components of component interfaces, thus making them visible within the interface definition.

ALIASES <alias name> FOR intf~comp.

Where, intf = interface name and comp = Component name

Accessing Objects using Interface References:

It is also possible to directly generate an object to which the interface reference

variable points initially. In this case, the TYPE addition of the statement CREATE OBJECT must be used to specify a class that implements the interface. CREATE OBJECT iref TYPE class.

If the interface intf contains an attribute attr and an instance method meth, you can address them as follows:

Using the class reference variable:

Accessing an attribute attr: cref->intf~attr

Calling a method meth: CALL METHOD cref->intf~meth

Using the interface reference variable:

Accessing an attribute attr: iref->attr

Calling a method meth: CALL METHOD iref->meth

Accessing Static Components of Interfaces:

Use the name of the interface to access constants within an interface.

Accessing a constant const: intf=>const.

To access the other static components of an interface, use an object reference or the class class that is implementing the interface.

Accessing a static attribute attr: class=>intf~attr.

Calling a static method meth: CALL METHOD class=>intf~meth.

Example:

an interface is implemented with the method add_employee. Note that the interface is only implemented in the superclass ( The INTERFACE stament), but also used in the subclasses.

The interface in the example only contains a method, but an iterface can also contain attrbutes, constants, types and alias names.

REPORT zbc404_hf_events_3 .

INTERFACE lif_employee

INTERFACE lif_employee.

METHODS:

add_employee

IMPORTING im_no TYPE i

im_name TYPE string

im_wage TYPE i.

ENDINTERFACE.

*******************************************************

Super class LCL_CompanyEmployees

*******************************************************

CLASS lcl_company_employees DEFINITION.

PUBLIC SECTION.

INTERFACES lif_employee.

TYPES:

BEGIN OF t_employee,

no TYPE i,

name TYPE string,

wage TYPE i,

END OF t_employee.

METHODS:

constructor,

add_employee "Removed

IMPORTING im_no TYPE i

im_name TYPE string

im_wage TYPE i,

display_employee_list,

display_no_of_employees.

PRIVATE SECTION.

CLASS-DATA: i_employee_list TYPE TABLE OF t_employee,

no_of_employees TYPE i.

ENDCLASS.

*-- CLASS LCL_CompanyEmployees IMPLEMENTATION

CLASS lcl_company_employees IMPLEMENTATION.

METHOD constructor.

no_of_employees = no_of_employees + 1.

ENDMETHOD.

METHOD lif_employee~add_employee.

Adds a new employee to the list of employees

DATA: l_employee TYPE t_employee.

l_employee-no = im_no.

l_employee-name = im_name.

l_employee-wage = im_wage.

APPEND l_employee TO i_employee_list.

ENDMETHOD.

METHOD display_employee_list.

Displays all employees and there wage

DATA: l_employee TYPE t_employee.

WRITE: / 'List of Employees'.

LOOP AT i_employee_list INTO l_employee.

WRITE: / l_employee-no, l_employee-name, l_employee-wage.

ENDLOOP.

ENDMETHOD.

METHOD display_no_of_employees.

Displays total number of employees

SKIP 3.

WRITE: / 'Total number of employees:', no_of_employees.

ENDMETHOD.

ENDCLASS.

*******************************************************

Sub class LCL_BlueCollar_Employee

*******************************************************

CLASS lcl_bluecollar_employee DEFINITION

INHERITING FROM lcl_company_employees.

PUBLIC SECTION.

METHODS:

constructor

IMPORTING im_no TYPE i

im_name TYPE string

im_hours TYPE i

im_hourly_payment TYPE i,

lif_employee~add_employee REDEFINITION..

PRIVATE SECTION.

DATA:no TYPE i,

name TYPE string,

hours TYPE i,

hourly_payment TYPE i.

ENDCLASS.

*---- CLASS LCL_BlueCollar_Employee IMPLEMENTATION

CLASS lcl_bluecollar_employee IMPLEMENTATION.

METHOD constructor.

The superclass constructor method must be called from the subclass
constructor method

CALL METHOD super->constructor.

no = im_no.

name = im_name.

hours = im_hours.

hourly_payment = im_hourly_payment.

ENDMETHOD.

METHOD lif_employee~add_employee.

Calculate wage an call the superclass method add_employee to add
the employee to the employee list

DATA: l_wage TYPE i.

l_wage = hours * hourly_payment.

CALL METHOD super->lif_employee~add_employee

EXPORTING im_no = no

im_name = name

im_wage = l_wage.

ENDMETHOD.

ENDCLASS.

*******************************************************

Sub class LCL_WhiteCollar_Employee

*******************************************************

CLASS lcl_whitecollar_employee DEFINITION

INHERITING FROM lcl_company_employees.

PUBLIC SECTION.

METHODS:

constructor

IMPORTING im_no TYPE i

im_name TYPE string

im_monthly_salary TYPE i

im_monthly_deductions TYPE i,

lif_employee~add_employee REDEFINITION.

PRIVATE SECTION.

DATA:

no TYPE i,

name TYPE string,

monthly_salary TYPE i,

monthly_deductions TYPE i.

ENDCLASS.

*---- CLASS LCL_WhiteCollar_Employee IMPLEMENTATION

CLASS lcl_whitecollar_employee IMPLEMENTATION.

METHOD constructor.

The superclass constructor method must be called from the subclass
constructor method

CALL METHOD super->constructor.

no = im_no.

name = im_name.

monthly_salary = im_monthly_salary.

monthly_deductions = im_monthly_deductions.

ENDMETHOD.

METHOD lif_employee~add_employee.

Calculate wage an call the superclass method add_employee to add
the employee to the employee list

DATA: l_wage TYPE i.

l_wage = monthly_salary - monthly_deductions.

CALL METHOD super->lif_employee~add_employee

EXPORTING im_no = no

im_name = name

im_wage = l_wage.

ENDMETHOD.

ENDCLASS.

*******************************************************

R E P O R T

*******************************************************

DATA:

Object references

o_bluecollar_employee1 TYPE REF TO lcl_bluecollar_employee,

o_whitecollar_employee1 TYPE REF TO lcl_whitecollar_employee.

START-OF-SELECTION.

Create bluecollar employee obeject

CREATE OBJECT o_bluecollar_employee1

EXPORTING im_no = 1

im_name = 'Gylle Karen'

im_hours = 38

im_hourly_payment = 75.

Add bluecollar employee to employee list

CALL METHOD o_bluecollar_employee1->lif_employee~add_employee

EXPORTING im_no = 1

im_name = 'Karen Johnson'

im_wage = 0.

Create whitecollar employee obeject

CREATE OBJECT o_whitecollar_employee1

EXPORTING im_no = 2

im_name = 'John Dickens'

im_monthly_salary = 10000

im_monthly_deductions = 2500.

Add bluecollar employee to employee list

CALL METHOD o_whitecollar_employee1->lif_employee~add_employee

EXPORTING im_no = 1

im_name = 'Gylle Karen'

im_wage = 0.

Display employee list and number of employees. Note that the result
will be the same when called from o_whitecollar_employee1 or
o_bluecolarcollar_employee1, because the methods are defined
as static (CLASS-METHODS)

CALL METHOD o_whitecollar_employee1->display_employee_list.

CALL METHOD o_whitecollar_employee1->display_no_of_employees.

Message was edited by:

Sudha Rani Pathuri

Re: interfaces.

Former Member — Fri, 29 Jun 2007 04:47:41 GMT

Hi Ashok,

Refer the foll. link .. it ll take u thru the basics of OO-ABAP as well as Interface

https://www.sdn.sap.com/irj/sdn/wiki?path=/display/abap/objectOrientedABAP+(OO-ABAP)&

Hope this helps.

Re: interfaces.

Former Member — Fri, 29 Jun 2007 04:50:24 GMT

Hi,

Give me your mail id.

Thanks,

Anitha

Re: interfaces.

seshatalpasai_madala — Fri, 29 Jun 2007 04:51:14 GMT

Hi,

Interfaces are similar to classes where in you will not have any METHOD implementations. You will only have Attributes and METHOD definitions.

Interfaces have to be implemented by Classes.

The use is that One interface can be implemented by any number of classes.

SO using an interface reference you can work on MANY TYPES OF CLASS objects.

For example.

DATA: intf type ref to Interface1.

Suppose Class1 class2 ... classn are implemnting this interface1.

then we can

intf = clas1_obj.

intf = clas2_obj.

intf = clasn_obj.

SO one reference can be used to work with many objects of different classes.

Regards,

Sesh

Re: interfaces.

Former Member — Fri, 29 Jun 2007 04:57:18 GMT

hi,

ashuvalal@gmail.com

Thank you

Ashok

Re: interfaces.

Former Member — Fri, 29 Jun 2007 05:02:25 GMT

Hi,

Check your mail.

Thanks,

Anitha

Re: interfaces.

jaideeps — Fri, 29 Jun 2007 13:33:27 GMT

hi,

interface concepts are related to OOP concepts in abap.. in general interface conatin only the definition of a method..and the implemenation is done in the class.

check out this code..copy and paste it in se38..or check with abapdocu tcode..

REPORT demo_interface.

INTERFACE status.

METHODS write.

ENDINTERFACE.

CLASS counter DEFINITION.

PUBLIC SECTION.

INTERFACES status.

METHODS increment.

PRIVATE SECTION.

DATA count TYPE i.

ENDCLASS.

CLASS counter IMPLEMENTATION.

METHOD status~write.

WRITE: / 'Count in counter is', count.

ENDMETHOD.

METHOD increment.

ADD 1 TO count.

ENDMETHOD.

ENDCLASS.

CLASS bicycle DEFINITION.

PUBLIC SECTION.

INTERFACES status.

METHODS drive.

PRIVATE SECTION.

DATA speed TYPE i.

ENDCLASS.

CLASS bicycle IMPLEMENTATION.

METHOD status~write.

WRITE: / 'Speed of bicycle is', speed.

ENDMETHOD.

METHOD drive.

ADD 10 TO speed.

ENDMETHOD.

ENDCLASS.

DATA: count TYPE REF TO counter,

bike TYPE REF TO bicycle,

status TYPE REF TO status,

status_tab TYPE TABLE OF REF TO status.

START-OF-SELECTION.

CREATE OBJECT: count, bike.

DO 5 TIMES.

CALL METHOD: count->increment,

bike->drive.

ENDDO.

APPEND: count TO status_tab,

bike TO status_tab.

LOOP AT status_tab INTO status.

CALL METHOD status->write.

ENDLOOP.

thanks

jaideep

reward points if it is useful..

Re: interfaces.

Former Member — Fri, 29 Jun 2007 14:22:26 GMT

HI,

see this example.

REPORT ZINTERFACE.

INTERFACE inter1.

DATA:inter1_num TYPE i.

METHODS:inter1_meth importing value(number1) type i.

ENDINTERFACE.

INTERFACE inter2.

DATA:inter2_num TYPE i.

METHODS:inter2_meth importing value(number2) type i.

ENDINTERFACE.

CLASS clas1 DEFINITION.

PUBLIC SECTION.

INTERFACES:inter1,inter2.

DATA:cls_num TYPE i.

METHODS:cls_meth.

ENDCLASS.

CLASS clas1 IMPLEMENTATION.

METHOD inter1~inter1_meth.

cls_num = number1 + number1.

inter1~inter1_num = cls_num + cls_num.

write:/ 'i am from first interface'.

write:/ number1,/ cls_num,/ inter1~inter1_num.

ENDMETHOD.

METHOD inter2~inter2_meth.

cls_num = number2 + number2 + number2.

inter2~inter2_num = cls_num + cls_num + cls_num.

write:/ 'i am from second interface'.

write:/ number2,/ cls_num,/ inter2~inter2_num.

ENDMETHOD.

METHOD cls_meth.

write:/ 'i am from class'.

ENDMETHOD.

ENDCLASS.

START-OF-SELECTION.

DATA:myinput TYPE i value 20.

DATA:obj TYPE REF TO clas1.

CREATE OBJECT obj.

CALL METHOD obj->inter1~inter1_meth

exporting number1 = myinput.

CALL METHOD obj->inter2~inter2_meth

exporting number2 = myinput.

CALL METHOD obj->cls_meth.

rgds,

bharat.