OOABAP

Object-  Object  -Oriented  Oriented  Programming in  ABAP  Presented by Pooja Nayak

OOPS O OPS iin n ABAP ABAP

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SESSION OVERVIEW 

What is Object Orientation?

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Attributes Attri butes of Object Oriented Programming

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ABAP Objects

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How to implement classes,events...

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Advantages of OOP in ABA ABAP P

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SAP Business Objects

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Object Orientation tools in ABA ABAP P

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What is Object Orientatio Orientation? n? 

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Type of problemproblem-solving -solving method in which the software s oftware solution reflects realreal-world -world objects. Emphasis is given to data rather than to procedures Data is hidden and cannot be accessed by external functions.

Merits Of Object Orientation 

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Complex software systems become easier to understand. OO systems are easier to scale by using the concept of  reusability.

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 Attributes of Object Oriented Programming Objects Classes Data Encapsulation Inheritance Polymorphism

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OBJECTS 

Is any realreal-time -time entity (eg. Employee, customer etc )

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Contains data and behaviour.

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Operations are done through message passing.

Format of message is  message:[destination,operation,parameters]

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destination

receiver object stimulated by message

operation

method that is to receive the message

parameters

information informatio n needed for operation to be successful.

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CLASS   

Central element of object orientation.  Abstract description of an object. Defines state and behaviour of objects.

Structure of Class 

Classes contain component components. s.

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Each component is assigned a visibility section.

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Components implement methods.

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Data Encapsulatio Encapsulation n 

Protective covering preventing data and code from being defined outside the covering.

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Each obj. has an interface, which determines how other obj. can interact with it.

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Objs restrict visibility of their resources to other users.

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Three visibility mechanisms.

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Private section

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Public section

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Protected section

 All components components defined in public section are accessible to all users of the class, c lass, methods of the class and any inherited classes. OOPS O OPS iin n ABAP ABAP

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Data Encapsulation contd.. 

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 All components components declared in private section are only visible in the methods of same class.  All components declared in protected section are visible to methods methods of the class and those classes c lasses that inherit from this class. Interfaces completely describes how the user of the class interacts with it.  Attributes will be hidden and user will use methods of  class to manipulate manipulate the data.

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INHERITANCE 

Relationship Relationshi p in which a class (subclass) inherits the main features of another class (superclass).

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Subclass can add new components (attributes, methods, events) and replace replace inherited inherited methods methods with its own implementation. Types of Inheritance 1)

Single level Inheritance

2)

Multiple

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Hierarchical

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Hybrid

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POLYMORPHISM  

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Comes from the Greek word ³many forms´.  Allows one interface to be used for a general class of  actions. When objects from different classes react differently to the same procedural call. User can work with different classes in a similar way, regardless of their impleme implementation. ntation.  Allows improved code organization and readability as well as creation of ³extensible´ programs.

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 ABAP Objects 

Complete set of ObjectObject-Oriented -Oriented statements introduced in conventional ABAP.

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 ABAP Objects was introduced with SAP Basis Release 4.5 

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Classes, Interfaces, Events

 ABAP Objects was completed with SAP Basis Release 4.6 

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Inheritance, Dynamic Invoke

Some enhancements were added with SAP Web W eb Application Server, Releases 6.10, 6.20. 

Friends, Shared Objects

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 ABAP Objects contd.. Runtime environment 

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 ABAP Workbench allows you to create R/3 Repository Objects like programs, lock objects and so on. Using Function Modules, we can encapsulate functions in different programs with defined interfaces.

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Object Oriented enhancement of ABAP is based on models of Java and C++.

Object References 

Used to access objects from ABAP program and contained in reference variables ( pointers to objects ).

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 ABAP Objects contd« 

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Two types of references -

C Class lass References References Interface References. Class References are defined using the addition TYPE REF TO

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in the TYPES or DATA statement. It allows the user to create an instance of the class. Interface References are defined using the addition « TYPE REF TO

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in the TYPES or DATA statement. should be declared before actual reference declaration occurs. OOPS O OPS iin n ABAP ABAP

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 ABAP Objects contd« 

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 After creating a reference variable for a class, you can create an object using the statement CREAT CRE CREATE ATE E OB OBJE OBJECT JECT CT . This creates an instance of the object and contains the reference to the object.

 Addressing the components of objects Instance componen c omponents ts 

To access attributes :

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CALL  METHOD METHO MET HOD D To access methods : CALL -> ->

  ref> ->  ->   

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Static components  

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To access attributes :

<

class> => .

To access methods : =>

CA ALL LL

METH ME METHOD THOD OD

Within a class, you can access individual componen components ts using the keyword ME. For example: ME --> > CA ALL LL

METH THOD OD M ME E -> -> .

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Classes in ABAP Types of Classes Local Classes 

Defined within ABAP program.

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Can be used only with that program.

Global Classes 

Defined in class builder SE24.

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Stored centrally in class library in R/3 repository.

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Can be accessed from all programs in R/3 system. CL_GUI_ALV_G RID, For eg. CL_GUI_CUSTOM_CONTAINER

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Defining local classes in ABAP 

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The main components are Attributes Attributes,, Methods and Events. In ABAP, classes are defined between CLASS and ENDCLASS statements. Class definition definition consists of declaration and implementation parts. Syntax for class definition is CLASS classname DEFINITION . PUBLIC SEC PUBLIC SECTIO SECTION TION N. *declare public variables and methods.

PRIVAT PRI PRIVATE VATE E SEC SECTIO SECTION TION N. *declare private data. ENDCLASS. OOPS O OPS iin n ABAP ABAP

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Understanding Understandin g Classes contd.. 

The syntax for class implementation is CLASS class_name IMPLEMENTAT IMPLEMENTATION. ION. METHOD CONSTRUCTOR. *initialising *initialisin g the variables ENDMETHOD. METHOD method_name. *write code for the defined methods ENDMETHOD. ENDCLASS. OOPS O OPS iin n ABAP ABAP

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Understanding Class Components  Attributes They are internal data variables in a class and can take  any ABAP data type.  Can be classified into instance insta in stance nce att attrib attr at trib ribute ibut utes es s an and d static attributes.. attributes  Instan Ins Instance tance ce att attrib attribut attr ribute ibutes utes es s are declare dec declared lared d using DATA keyword keyword keyw ord and determine the state of the instance.  Must create an object before working with instance attributes.  Static at Static attri attribut attr tribut ibutes butes es are declared declared decla red using using CLASS CLAS CLASSS-DATA -DATA keyword and determine the state of the class.  Need not create an object before working with static attributes. OOPS O OPS iin n ABAP ABAP

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Methods( Procedures) Methods( 

They can access all class attributes and have parameter  interface similar to the Function Modules (IMPORTING, EXPORTING, CHANGING).

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Like Attributes, there are instance methods and static methods. Instance methods methods are declared using METHODS keyword keywor d and can access all the attributes of the class. Static methods methods are declared using CLASSCLASS -METHODS -METHODS keyword and can access only static attributes of the class.

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The syntax of using methods is METHODS IMPORTING : [VALUE(] [)]TYPE type] [OPTIONAL] EXPORTING : [VALUE(] [)] TYPE type] [OPTIONAL] CHANGING

: [VALUE(] [)] TYPE type]

[OPTIONAL] RETURNING VALUE() EXCEPTIONS: . 

The additions like IMPORTING, EXPORTING etc define attributes of interface parameters like passpass -by -by by--value -value (VALUE), its type (TYPE) and if it is optional (like OPTIONAL). OOPS O OPS iin n ABAP ABAP

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Implementing methods 

The syntax for implementation implem entation of a method is METHOD methodname. *enter the code here ENDMETHOD.. ENDMETHOD

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The interface parameters needn¶t be specified in implementation. implem entation. To handle error situations, statements like RAISE , MESSAGE RAISING etc can be used.

Calling Methods 

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The way of addressing a method depends on the method itself and from where you are calling it. The basic form of calling a method is CALL METHOD methodname. OOPS O OPS iin n ABAP ABAP

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Class Definition --> > An Example CLASS CL_EMPLOYEE DEFINITION. PUBLIC SECTION. TYPES: BEGIN OF T_EMPLOYEE, NO TYPE I, NAME TYPE STRING, END OF T_EMPLOYEE.

 METHODS: CONSTRUCTOR  IMPORTING: IM_EMPLOYEE_NO TYPE I IM_EMPLOYEE_NAME TYPE STRING,

DISPLAY_EMPLOYEE. OOPS O OPS iin n ABAP ABAP

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 METHODS: DISPLAY_NO_OF_EMPLOYEES. PROTECTED SECTION. DATA : G_NO_OF_EMPLOYEES TYPE I. PRIVATE SECTION. DATA  G_EMPLOYEE TYPE T _EMPLOYEE. ENDCLASS. CLASS CL_EMPLOYEE IMPLEMENTATION.  METHOD CONSTRUCTOR. OYEE-NO -NO = IM_EMPLOYEE_NO. G_EMPLOYEEOYEE-N -NAME = IM_EMPLOYEE_NAME. G_EMPLOYEEG_NO_OF_EMPLOYEES = G_NO_OF_EMPLOYEES + 1.

ENDMETHOD. OOPS O OPS iin n ABAP ABAP

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Class Implementatio Im Implementation plementation n --> > An Example CLASS CL_EMPLOYEE IMPLEMENTATION.  METHOD CONSTRUCTOR. OYEE-NO -NO = IM_EMPLOYEE_NO. G_EMPLOYEEG_EMPLOYEEOYEE-N -NAME = IM_EMPLOYEE_NAME. G_NO_OF_EMPLOYEES = G_NO_OF_EMPLOYEES + 1. ENDMETHOD.  METHOD DISPLAY_EMPLOYEE. WRITE:/ µEmployee Number¶,G_EMPLOYEE_NO. WRITE:/ 'Employee Name', G_EMPLOYEEOYEE-N -NAME. ENDMETHOD.  METHOD DISPLAY_NO_OF_EMPLOYEES. WRITE:/ 'Number of employees is : ', G_NO_OF_EMPLOYEES. ENDMETHOD. ENDCLASS.

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DATA  : G_EMPLOYEE1 TYPE REF TO LCL_EMPLOYEE. START-OF-SELECTION. CREATE OBJECT G_EMPLOYEE1

EXPORTING IM_EMPLOYEE_NO = 1 IM_EMPLOYEE_NAME = 'John Jones'.

CALL  METHOD G_EMPLOYEE1->DISPLAY_EMPLOYEE. CALL  METHOD G_EMPLOYEE1->DISPLAY_ NO_OF_EMPLOYEES.

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CLASS COMPONENTS contd« Events 

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Events are used to trigger event event--handler -handler methods in objects or classes. When an event is triggered, any no: of handler methods can be called and the handler determines events to which it want to react. Events of a class can be triggered in the methods m ethods of same class using RAISE EVENT statement.  A method of same or different class can be declared as an event handler method for f or the event of class by giving the addition FOR EVENT OF .

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The link between between handler and trigger is established at runtime using the statement SET HANDLER. OOPS O OPS iin n ABAP ABAP

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Handling and Triggering Events To trigger an event, a class must a) declare the event in declaration part b) trigger the event in one of its events. Declaring Events  To declare instance events, EVENTS EXPORTING.. VALUE() TYPE type [OPTIONAL].  To declare static events, CLASS--EVENTS CLASS -EVENTS .. 

Triggering Events  Instance events can be triggered by any method in the class while static events can be done using only static methods. RAISE EVENT EXPORTING = .. OOPS O OPS iin n ABAP ABAP

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Handling Events 

To handle an event, a method must a) be defined as an event handler method for that event. b) be registered at runtime for the event.

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To declare an event handler method, use following statement. METHODS FOR EVENT OF IMPORTING ei> = (for instance method).

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To register event handler method, use the following statement. SET HANDLER.. .. FOR..

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 After the RAISE EVENT statement, all registered event handler  methods are executed before the next statement is processed. Handler methods are executed in the order in which are registered./

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Event Handling --> > An example REPORT ZGAS_NEW . CLASS counter DEFINITION. PUBLIC SECTION. METHODS increment _counter. EVENTS critical _value EXPORTING value(excess) TYPE i. PRIVATE SECTION. TYPE i , DATA: count threshold TYPE i  VALUE 10. ENDCLASS. CLASS handler DEFINITION. PUBLIC SECTION.

excess FOR  EVENT  METHODS handle _ ex OF counter IMPORTING excess. ENDCLASS. OOPS O OPS iin n ABAP ABAP

critical _value

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CLASS counter IMPLEMENTATION.

METHOD increment _counter. DATA diff TYPE i. ADD 1 TO count. IF count > threshold.

diff = count - t threshold. hr esho ld.

RAISE EVENT critical _value EXPORTING excess = diff. ENDIF. ENDMETHOD. ENDCLASS. OOPS O OPS iin n ABAP ABAP

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CLASS handler IMPLEMENTATION.

excess.  METHOD handle _ ex  WRITE: / 'Excess is', excess. ENDMETHOD. ENDCLASS. DATA: r1 TYPE REF TO counter ,

h1 TYPE REF TO handler. RT-OF -OF OF-SELECTION. STARTCREATE OBJECT: r1, h1.

SET HANDLER  h1h1->handle ->handle _ ex excess FOR   ALL INSTANCES. DO 20 TIMES.

r1->increment ->increment _counter. CALL METHOD r1ENDDO.

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Constructors Special methods called automatically by the system to set the starting state of an object or class.  Called when a class is instantiated. Types of Constructors 

Instance constructors  Declared using keyword METHODS CONSTRUCTOR  Used to initialize instance attributes. Static Constructors  Declared using CLASSCLASS-METHODS -METHODS CLASS CONSTRUCTOR.  Used to initialize static attributes.  Constructor implementation is similar to a method implementation.

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Inheritance 

The statement is CLASS DEFINTION INHERITING FROM .

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 A class can have more than one subclass, but may have only one superclass(single inheritance). OBJECT C1

C2

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Inheritance contd« 

When subclasses inherit from superclass, which itself a subclass of another class, all classes form inheritance tree.

Redefining Methods 

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Use the addition REDEFINITION in METHODS statement to redefine redefine public or protected instance method in a subclass. The method retains the name and interface, but with a new implementation. OOPS O OPS iin n ABAP ABAP

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Interfaces 

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Exclusively describes the external point of contact, but don¶t contain any implementation part. Has only declaration part, in the public section of  classes.  A class can implement any number of interfaces and interface can be implemented by any number of classes. Interface resolution resolution operator(~ operator(~)) enables to access interface components components using an object reference belonging to the class implementing the interface. OOPS O OPS iin n ABAP ABAP

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Defining Interfaces 

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Use the statement INTERFACE ------------------------ENDINTERFACE. Can be defined either globally in R/3 repository or  locally in ABAP program. You can define the same components in an interface as in a class. Components Componen ts don¶t have to be assigned individually to a visibility section. Interfaces don¶t have an implementation part, since their  methods are implemented in the class that implements it. OOPS O OPS iin n ABAP ABAP

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Implementing Interfaces 

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Use in the declaration part of the class (public section), INTERFACES . During implementation, components are added to other  components componen ts in the public section. The class must implement the methods of all interfaces implemented in it . The implementation implementation part of the class must contain a method implementation for each interface method : METHOD -----------------------------ENDMETHOD. OOPS O OPS iin n ABAP ABAP

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 Advantages  Advanta ges of OOPS in ABAP 

The implementation of object-oriented elements in  ABAP language has considerably increased response times.

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Use of OOPS in ABAP helps to have a better control of development complexity, a better means for  encapsulation and extensibility.

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Reusability of the objects will reduce the coding effort and helps in utilizing the existing code for other  programs.

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Object Orientation Orientation Tools T ools in ABAP  ABAP Class Builder   

Transaction T ransaction Code: Code:

S SE24. E24.

 Allows you to create and maintain global classes and interfaces.

Features 

Display an overview of global data types and their  relationships.

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Create and specify attributes, methods and events of global classes and interfaces.

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Create internal types in a class.

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Implement methods. OOPS O OPS iin n ABAP ABAP

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HOW TO USE ALV USING OOPS

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Tcode: SE38 Create

a program

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Goto

Flow Logic and click on layout

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Add a Custom Control on the screen

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Give

a name to custom control

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Declare Gobal variables to be used for ALV Grid

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Fill internal table with list data to be displayed

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In

PBO of the flow logic, write w rite a module and inside the module write the code

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If ALV Grid Creating

instance not exist.

custom container instance

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Creating

ALV AL V Grid instance

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Call

the method for data display

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If ALV Grid

instance already exists

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Output

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If we assign values for layout structure fields

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Output

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THANK YOU

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