SAP ABAP FAQs- Part 3 (Object Oriented ABAP)

SAP OOABAP Interview Questions Answers

1. Explain about Object oriented programming?

Object oriented programming is one of the most popular methodologies in

software development. It offers a powerful model for creating computer programs.

It speeds the program development process, improves maintenance and enhances

Reusability of programs.

2. Object oriented Concepts?

Encapsulation:

It means combining data and code that acts up on data into one single unit of

organization, so that both are safe from out side interference. In OOAbap

encapsulation is achieved through classes.

Polymorphism:

It means many forms that mean the same method behaves differently in different

method calls.

Inheritance:

It means deriving a child class from base class; child class acquires all the

properties from base class.

Abstraction:

Abstraction simplifies a complex problem to a simpler problem by specifying and

modeling the class to the relevant problem scenario.

It simplifies the problem by giving the class its specific class of inheritance.

Composition also helps in solving the problem to an extent.

3. What is a 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.

4. What is an object?

An object is a combination of messages and data. Objects can receive and send

messages and use messages to interact with each other. The messages contain

information that is to be passed to the recipient object.

5. How many types of classes are there in OOABAP?

Public class

Private class

Final class

Singleton

class

Abstract class

Persistent class

Friend class

6. What is the difference between function group and classes?

We can create many instances of the same class with in a program, but we cannot

create many instances of function group.

7. What are the differences local & global classes?

Local classes are defined locally with in a program and the other programs can’t

access the same classes directly.

But global classes are not like that they are globally accessible from ABAP

environment. Global classes are centrally defined in a repository. Transaction code

for global classes is SE24(class builder).

8. What are the Components of a class?

Attributes and methods are components inside a class.

9. How to define a class locally?

class definition.

Public section.

Methods: m1 importing p1 type

Exporting p2 type

Changing p3 type

Returning p4 type

Exceptions .

Protected section.

Private section.

Endclass.

Class implementation.

Method m1.

Endmethod.

Endclass.

10. What is a constructor & types of constructors?

Constructor is a special method, which will be called automatically as and when

the object is created for a class, it can have only importing parameters but not

exporting, it is generally used to give some initial state to the object.

A class can contain have two types of constructors static and instance

constructors.

11. Difference between static and instance constructors?

Static constructor will be called only once, i.e. at the time of loading class in to

memory. Instance constructors are instance specific, these constructors will be

called as and when the new object is created for that class.

12. How to a create object for the class?

Data: ref type ref to .

Create object ref.

13. how to call a method?

Call method ref>

method_name .

14. What is static attribute & method?

Static attributes & methods are class specific, memory will be allocated only once

for Static attributes & methods irrespective of no. of objects created.

We can access the components with a reference variable i.e. by using class name

Call method =>menthod_name.

15. Can we instantiate a class within implementation of other class?

Yes

16. Can we put non declarative statement e.g. STARTOFSELECTION

within a class?

No, we can’t use.

17. How to create a global class?

With tcode SE24

18. How can we pass importing parameter?

Pass by value/pass by reference

19. Can we pass returning parameter by reference?

NO, only pass by value

20. Can a method call itself?

Yes

21. What is me variable?

It just like a selfreference, by this we can call methods that are with in same class

with out creating object.

22. Can we have export parameter in Instance constructor? No

23. What is an abstract class?

Abstract class contains both abstract methods and normal methods, abstract

methods cannot implement in side abstract class, and instead these methods will

be implemented by child classes of that abstract class.

24. What is final class & Method?

Final classes can’t be inherited that means it can not have child classes and final

method of a class cannot be redefined.

25. What is an interface?

Interfaces contain only public methods with no implementation; these interfaces

are included in public section of classes and implement the methods of interfaces.

26. Can we implement interface in private section of any class?

No

26. What is alias?

Instead of specifying full name of interface methods, we can assign it a name

which can directly trigger.

28. What is a friend class?

Friend class is a class it can access private components of it’s friends class.

29. How to create an object for private class?

In general we can not create object for a private class, but we can access static

method of a private class so call that method using its class name and import that

object.

For example take one static method with an exporting parameter inside private

class and write object creation code in that static method and export that object.

30. What is a Singleton class?

Singleton classes can be instantiated only once, i.e. only one object is created for

Singleton classes.

31. What is a Persistent class?

A special class, the attributes of which are linked to database tables via objectrelational

mapping. Since Release 6.10 they can be created using the Mapping Assistant of the Class Builder.

The objects of persistent classes are managed by Object Services. An object in a

persistent class, the attributes of which are saved as database content after the

run time of an ABAP program.