Calss

[Former Member]

Hi.

what is the use of CLASS in ABAP. is this is same as c++.

please explain how to use this in ABAP.

[Former Member]

Hi

Yes, It is the same concept that is used in ABAP

same OOPS concepts holds good for the classes in ABAP also

properties like Inheritance, Polymorphisam, Abstraction and encapsulation holds good here in OOPS ABAP also

After the launch of NETWEAVER technology ABAP is also fully converted and using all OOPS related coding in most of its transactions

See for example PO transaction ME22N program you will find all classes and methods coding.

There are Local classes as well as Global Classes.

Local classes we can work in SE38 straight away.

But mostly it is better to use the Global classes.

Global Classes or Interfaces are to be created in SE24.

SAP already given some predefined classes and Interfaces.

This OOPS concepts very useful for writing BADI's also.

So first create a class in SE 24.

Define attributes, Methods for that class.

Define parameters for that Method.

You can define event handlers also to handle the messages.

After creation in each method write the code.

Methods are similar to ABAP PERFORM -FORM statements.

After the creation of CLass and methods come to SE38 and create the program.

In the program create a object type ref to that class and with the help of that Object call the methods of that Class and display the data.

You will also use them in BADI's (business ADD-IN's)

<b>Reward points for useful Answers</b>

Regards

Anji

Message was edited by:

Anji Reddy Vangala

[Former Member]

Hi

Both are same. No Big differences between them. Check this about class

Classes are templates for objects. Conversely, you can say that the type of an object is the same as its class. A class is an abstract description of an object. You could say that it is a set of instructions for building an object. The attributes of objects are defined by the components of the class, which describe the state and behavior of objects.

<u><b>Local and Global Classes</b></u>

Classes in ABAP Objects can be declared either globally or locally. You define global classes and interfaces in the Class Builder (Transaction SE24) in the ABAP Workbench. They are stored centrally in class pools in the class library in the R/3 Repository. All of the ABAP programs in an R/3 System can access the global classes. Local classes are defined within an ABAP program. Local classes and interfaces can only be used in the program in which they are defined. When you use a class in an ABAP program, the system first searches for a local class with the specified name. If it does not find one, it then looks for a global class. Apart from the visibility question, there is no difference between using a global class and using a local class.

There is, however, a significant difference in the way that local and global classes are designed. If you are defining a local class that is only used in a single program, it is usually sufficient to define the outwardly visible components so that it fits into that program. Global classes, on the other hand, must be able to be used anywhere. This means that certain restrictions apply when you define the interface of a global class, since the system must be able to guarantee that any program using an object of a global class can recognize the data type of each interface parameter.

The following sections describe how to define local classes and interfaces in an ABAP program. For information about how to define local classes and interfaces, refer to the Class Builder section of the ABAP Workbench Tools documentation.

<u><b>Defining Local Classes</b></u>

Local classes consist of ABAP source code, enclosed in the ABAP statements CLASS ... ENDCLASS. A complete class definition consists of a declaration part and, if required, an implementation part. The declaration part of a class <class> is a statement block:

CLASS <class> DEFINITION. 
...
ENDCLASS.

It contains the declaration for all components (attributes, methods, events) of the class. When you define local classes, the declaration part belongs to the global program data. You should therefore place it at the beginning of the program.

If you declare methods in the declaration part of a class, you must also write an implementation part for it. This consists of a further statement block:

CLASS <class> IMPLEMENTATION.
...
ENDCLASS.

The implementation part of a class contains the implementation of all methods of the class. The implementation part of a local class is a processing block. Subsequent coding that is not itself part of a processing block is therefore not accessible.

<b><i>Structure of a Class</i></b>

The following statements define the structure of a class:

A class contains components

Each component is assigned to a visibility section

Classes implement methods

The following sections describe the structure of classes in more detail.

<u><b>Class Components</b></u>

The components of a class make up its contents. All components are declared in the declaration part of the class. The components define the attributes of the objects in a class. When you define the class, each component is assigned to one of the three visibility sections, which define the external interface of the class. All of the components of a class are visible within the class. All components are in the same namespace. This means that all components of the class must have names that are unique within the class.

There are two kinds of components in a class - those that exist separately for each object in the class, and those that exist only once for the whole class, regardless of the number of instances. Instance-specific components are known as instance components. Components that are not instance-specific are called static components.

In ABAP Objects, classes can define the following components. Since all components that you can declare in classes can also be declared in interfaces, the following descriptions apply equally to interfaces.

<u><b>

Attributes</b></u>

Attributes are internal data fields within a class that can have any ABAP data type. The state of an object is determined by the contents of its attributes. One kind of attribute is the reference variable. Reference variables allow you to create and address objects. Reference variables can be defined in classes, allowing you to access objects from within a class.

<u><b>Instance Attributes</b></u>

The contents of instance attributes define the instance-specific state of an object. You declare them using the DATA statement.

<u><b>

Static Attributes</b></u>

The contents of static attributes define the state of the class that is valid for all instances of the class. Static attributes exist once for each class. You declare them using the CLASS-DATA statement. They are accessible for the entire runtime of the class.

All of the objects in a class can access its static attributes. If you change a static attribute in an object, the change is visible in all other objects in the class.

<b><u>Methods</u></b>

Methods are internal procedures in a class that define the behavior of an object. They can access all of the attributes of a class. This allows them to change the data content of an object. They also have a parameter interface, with which users can supply them with values when calling them, and receive values back from them The private attributes of a class can only be changed by methods in the same class.

The definition and parameter interface of a method is similar to that of function modules. You define a method <met> in the definition part of a class and implement it in the implementation part using the following processing block:

METHOD <meth>.

...

ENDMETHOD.

You can declare local data types and objects in methods in the same way as in other ABAP procedures (subroutines and function modules). You call methods using the CALL METHOD statement.

<u><b>

Instance Methods</b></u>

You declare instance methods using the METHODS statement. They can access all of the attributes of a class, and can trigger all of the events of the class.

<b><u>Static Methods</u></b>

You declare static methods using the CLASS-METHODS statement. They can only access static attributes and trigger static events.

<u><b>Special Methods</b></u>

As well as normal methods, which you call using CALL METHOD, there are two special methods called CONSTRUCTOR and CLASS_CONSTRUCTOR, which are automatically called when you create an object (CONSTRUCTOR) or when you first access the components of a class (CLASS_CONSTRUCTOR).

<u><b>Events</b></u>

Objects or classes can use events to trigger event handler methods in other objects or classes. In a normal method call, one method can be called by any number of users. When an event is triggered, any number of event handler methods can be called. The link between the trigger and the handler is not established until runtime. In a normal method call, the calling program determines the methods that it wants to call. These methods must exist. With events, the handler determines the events to which it wants to react. There does not have to be a handler method registered for every event.

The events of a class can be triggered in the methods of the same class using the RAISE EVENT statement. You can declare a method of the same or a different class as an event handler method for the event <evt> of class <class> using the addition FOR EVENT <evt> OF <class>.

Events have a similar parameter interface to methods, but only have output parameters. These parameters are passed by the trigger (RAISE EVENT statement) to the event handler method, which receives them as input parameters.

The link between trigger and handler is established dynamically in a program using the SET HANDLER statement. The trigger and handlers can be objects or classes, depending on whether you have instance or static events and event handler methods. When an event is triggered, the corresponding event handler methods are executed in all registered handling classes.

<u><b>Instance Events</b></u>

You declare instance events using the EVENTS statement. An instance event can only be triggered in an instance method.

<u><b>Static Events</b></u>

You declare static events using the CLASS-EVENTS statement. All methods (instance and static methods) can trigger static events. Static events are the only type of event that can be triggered in a static method.

<b><i>See also Triggering and Handling Events.</i></b>

<u><b>Types</b></u>

You can define your own ABAP data types within a class using the TYPES statement. Types are not instance-specific, and exist once only for all of the objects in a class.

<u><b>Constants</b></u>

Constants are special static attributes. You set their values when you declare them, and they can then no longer be changed. You declare them using the CONSTANTS statement. Constants are not instance-specific, and exist once only for all of the objects in a class.

<u><b>Visibility Sections</b></u>

You can divide the declaration part of a class into up to three visibility areas:

CLASS <class> DEFINITION. 
  PUBLIC SECTION.
...
  PROTECTED SECTION.
...
  PRIVATE SECTION.
...
ENDCLASS.

These areas define the external visibility of the class components, that is, the interface between the class and its users. Each component of a class must be assigned to one of the visibility sections.

<u><b>Public Section</b></u>

All of the components declared in the public section are accessible to all users of the class, and to the methods of the class and any classes that inherit from it. The public components of the class form the interface between the class and its users.

<u><b>Protected Section</b></u>

All of the components declared in the protected section are accessible to all methods of the class and of classes that inherit from it. Protected components form a special interface between a class and its subclasses. Since inheritance is not active in Release 4.5B, the protected section currently has the same effect as the private section.

<u><b>Private Section</b></u>

Components that you declare in the private section are only visible in the methods of the same class. The private components are not part of the external interface of the class.

<u><b>Encapsulation</b></u>

The three visibility areas are the basis for one of the important features of object orientation - encapsulation. When you define a class, you should take great care in designing the public components, and try to declare as few public components as possible. The public components of global classes may not be changed once you have released the class.

For example, public attributes are visible externally, and form a part of the interface between an object and its users. If you want to encapsulate the state of an object fully, you cannot declare any public attributes. As well as defining the visibility of an attribute, you can also protect it from changes using the READ-ONLY addition.

Reward all helpfull answers

Regards

Pavan

[Former Member]

Hi,

The Concept is same for C++ & ABAP.

<b>Class:</b> Group of the characterstics that can be attributed to a product. A class is a grouping of similar objects according to common characterstics.

<b>Object orientation</b> in ABAP is an extension of the ABAP language that makes available the advantages of object-oriented programming, such as encapsulation, interfaces, and inheritance. This helps to simplify applications and make them more controllable.

<b>ABAP Objects</b> is fully compatible with the existing language, so you can use existing statements and modularization units in programs that use ABAP Objects, and can also use ABAP Objects in existing ABAP programs.

ABAP Objects offers a number of advantages, even if you want to continue using procedural programming. If you want to use new ABAP features, you have to use object-oriented interfaces anyway.

<b>Sharing Data:</b> With ABAP shared objects, you can aggregate data once at a central location and the different users and programs can then access this data without the need for copying.

<b>Exception Handling:</b> With the class-based exception concept of ABAP, you can define a special control flow for a specific error situation and provide the user with information about the error.

<b>Developing Persistency:</b> For permanent storage of data in ABAP, you use relational database tables by means of database-independent Open SQL, which is integrated in ABAP. However, you can also store selected objects transparently or access the integrated database or other databases using proprietary SQL.

<b>Connectivity and Interoperability:</b> The Exchange Infrastructure and Web services are the means by which developers can implement a service-oriented architecture. With Web services, you can provide and consume services independently of implementation or protocol. Furthermore, you can do so within NetWeaver and in the communication with other systems. With the features of the Exchange Infrastructure, you can enable, manage, and adapt integration scenarios between systems.

<b>Making Enhancements:</b> With the Enhancement Framework, you can enhance programs, function modules, and global classes without modification as well as replace existing code. The Switch Framework enables you activate only specific development objects or enhancements in a system.

Regards,

Padmam.

[Former Member]

hi

Yes, it is the same concept as in C++

Check this for basic concepts of OOPS

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/library/webas/abap/abap%20...

General Tutorial for OOPS

In transaction <b>ABAPDOCU</b> , you can find many example programs using ABAP OOPs

<b>reward points for useful ans</b>

Regards

Aarti

[Former Member]

Hi,

Look at this article https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/3e59b790-0201-0010-88aa-bc8a7f95...

Using Abap OO you :

Save time reusing your source code.

Extends the programs without make great changing's.

etc...

Regards,

Omkar.

[Former Member]

Hi,

Hi ,

OO ABAP is nothing but a class-method apprach to write ABAP codes and define them : below are few of the informations which will be of help for a newbie :

Types of attributes and the basic concepts :

Public attributes

Private attributes

Instance attributes

Static attributes

Public methods

Private methods

Constructor method

Static constructor

Protected components

Polymorphism

Public attributes

Public attributes are defined in the PUBLIC section and can be viewed and changed from outside the class. There is direct access to public attributes. As a general rule, as few public attributes should be defined as possible.

PUBLIC SECTION.

DATA: Counter type i.

Private attributes

Private attributes are defined in the PRIVATE section. The can only be viewes and changed from within the class. There is no direct access from outside the class.

PRIVATE SECTION.

DATA: name(25) TYPE c,

planetype LIKE saplane-planetyp,

Instance attributes

There exist one instance attribute for each instance of the class, thus they exist seperately for each object. Instance attributes are declared with the DATA keyword.

Static attributes

Static attributes exist only once for each class. The data are the same for all instances of the class, and can be used e.g. for instance counters. Static attributes are defined with the keyword CLASS-DATA.

PRIVATE SECTION.

CLASS-DATA: counter type i,

Public methods

Can called from outside the class

PUBLIC SECTION.

METHODS: set_attributes IMPORTING p_name(25) TYPE c,

p_planetype LIKE saplane-planetyp,

Private methods

Can only be called from inside the class. They are placed in the PRIVATE section of the class.

Constructor method

Implicitly, each class has an instance constructor method with the reserved name constructor and a static constructor method with the reserved name class_constructor.

The instance constructor is executed each time you create an object (instance) with the CREATE OBJECT statement, while the class constructor is executed exactly once before you first access a class.

The constructors are always present. However, to implement a constructor you must declare it explicitly with the METHODS or CLASS-METHODS statements. An instance constructor can have IMPORTING parameters and exceptions. You must pass all non-optional parameters when creating an object. Static constructors have no parameters.

Static constructor

The static constructor is always called CLASS_CONSTRUCTER, and is called autmatically before the clas is first accessed, that is before any of the following actions are executed:

Creating an instance using CREATE_OBJECT

Adressing a static attribute using <classname>-><attrbute>

Calling a ststic attribute using CALL METHOD

Registering a static event handler

Registering an evetm handler method for a static event

The static constructor cannot be called explicitly.

Protected components

When we are talking subclassing and enheritance there is one more component than Public and Private, the Protected component. Protected components can be used by the superclass and all of the subclasses. Note that Subclasses cannot access Private components.

Polymorphism

Polymorphism: When the same method is implemented differently in different classes. This can be done using enheritance, by redefining a method from the superclass in subclasses and implement it differently.

Chk this standard Programs.

ABAP_OBJECTS_ENJOY_0 Template for Solutions of ABAP Object Enjoy Course

ABAP_OBJECTS_ENJOY_1 Model Solution 1: ABAP Objects Enjoy Course

ABAP_OBJECTS_ENJOY_2 Model Solution 2: ABAP Objects Enjoy Course

ABAP_OBJECTS_ENJOY_3 Model Solution 3: ABAP Objects Enjoy Course

ABAP_OBJECTS_ENJOY_4 Model Solution 4: ABAP Objects Enjoy Course

ABAP_OBJECTS_ENJOY_5 Model Solution 5: ABAP Objects Enjoy Course

DEMO_ABAP_OBJECTS Complete Demonstration for ABAP Objects

DEMO_ABAP_OBJECTS_CONTROLS GUI Controls on Screen

DEMO_ABAP_OBJECTS_EVENTS Demonstration of Events in ABAP

Regards