SAP Object Oriented ABAP Interview Questions & Answers

Question 1. Is It Mandatory To Implement All Methods Of Interface In The Class Which Includes Interface?

Answer :

No it is not mandatory to implement all normal interface methods but it is mandatory to implement all Abstract methods.

Question 2. What Is An Interface In Ooabap?

Answer :

Interface is class which contains methods without implementations.

Question 3. Can We Instantiate The Interface?

Answer :

No, we can not instantiate interface using create object keyword.

Question 4. Can We Achieve Multiple Inheritance Using Interfaces?

Answer :

Yes, by using interface concept in SAP ABAp, we can achieve multiple inheritance

Question 5. Does Polymorphism Achieved Through Interfaces?

Answer :

Yes, by using interface concept in SAP ABAP, we can polymorphism

Question 6. What Is The Difference Between Abstract Class And Interface?

Answer :

Abstract class is a class which contains at least one abstract method( Method without implementation), Abstract class contains methods with implementation and without implementation and we cannot create instance for the abstract class .

• Abstract class is mainly for inheritance .
• Interface contains methods without implementation .

Question 7. What Is Alias Name In Ooabap?

Answer :

Alias is an alias name for the interface method implemented in the class .

Question 8. Can We Raise Events In Interface?

Answer :

No, you can not raise events in interface, Because there is no Implementation for the methods. We can create events in interfaces .

Question 9. What Is A Single-ton Class?

Answer :

Single-ton class is a class which allows to instantiate once only .

Question 10. What Is The Difference In Attributes Defined In The Public Versus Private Section Of A Class?

Answer :

Public attributes can be accessed by class, subclasses and other classes where as Private attributes can be accessed by class itself only.

Question 11. What Is The Difference In An Instance Method And A Static Method?

Answer :

Instance method is available separately in each object (instance), static method is global and no instance is required for static method.

Question 12. What Is A Class In Ooabap?

Answer :

Class is user defined data type which contains methods, events, attributes, interfaces etc.

Question 13. What Is The Difference Between Singleton And Static Class In Sap Abap ?

Answer :

Before going to static classes, you should understand static components.

• Static Components: Static components (static attributes, static events and static methods) exists globally, no need to create object/instance of the class to access them, we can access them by using static component selector => .
• Static Class: A class that only contains static components and no instance components is referred to as a static class.
• Singleton Class: It is a class which does not allow you to create multiple instances.

Question 14. Can We Make Methods Of Interface As Abstract And Final In Ooabap ?

Answer :

No we can not make interface methods as abstract or final in Object Oriented ABAP

Question 15. Can We Declare Events In Interface In Ooabap ?

Answer :

Yes, we can declare events in interface in Object Oriented ABAP

Question 16. What Is A Singleton Class In Ooabap ?

Answer :

Singleton class is a class which allows to instantiate(Create Object) only once .

Question 17. What Is A Global Class In Sap ?

Answer :

Global classes and interfaces are defined in the Class Builder (Transaction SE24) in the ABAP Workbench.All of the ABAP programs in an R/3 System can access the global classes

Question 18. What Is A Local Class In Sap ?

Answer :

Local classes are defined in an ABAP program (Transaction SE38) and can only be used in the program in which they are defined.

Question 19. What Is An Event In Ooabap ?

Answer :

Event is a mechanism by which method of one class can raise method of another class, without the hazard of instantiating that class.

Question 20. How To Declare And Raise Events In Ooabap ?

Answer :

We need to follow below steps when working with events in Object Oriented ABAP:

• Define an event
• Define a method
• Link event and method and convert the method into event-handler method
• Create a triggering method which will raise the event
• Use set handler and register event handler method to a particular instance in the program

Question 21. What Is A Constructor Method In Ooabap ?

Answer :

• These are special type of methods
• constructor method is executed automatically whenever a object is created or instantiated
• These methods are mainly used to set default values in a class
• The name of the constructor method is 'constructor'
• These methods have only importing parameters
• There are no exporting parameters

Question 22. What Is Abstract Method In Ooabap ?

Answer :

Abstract methods is a method which doesn't contain any implementation.

Question 23. What Is An Abstract Class In Ooabap ?

Answer :

• It is a class which contains methods with implementation as well as methods without implementation .
• Abstract class is a class which contains at least one abstract method.

Question 24. Can We Instantiate Abstract Class In Ooabap ?

Answer :

• we cannot create an object to the abstract class instead create an object to the child class and call the methods .
• Abstract class are mainly used for creating inheritance.

Question 25. What Is The Use Of 'defination Deferred' Keyword In Ooabap ?

Answer :

It is the keyword which indicates the class definition is delayed or postponed or Defined at some place in program.

Syntax : CLASSÂ Â DEFINITION DEFERED.

Question 26. What Are The Advantages Of Oo Alv ?

Answer :

Some of the main advantages of Object Oriented ALV

• We have no of events available in the classes when compared to ALV with function modules which gives flexibility for the programmer to develop ALV'S for various scenarios.
• We can display more than one ALV grid data on a single screen.
• The ALV grid data is displayed in the form of custom container with which we can control the size of ALV grid Whereas we cannot control the size of the ALV with function Modules.
• We can also place different UI elements like checkbox, Radiobutton on the same screen in addition ALV grid data.

Question 27. What Are The Types Of Constructor's In Ooabap ? Explain ?

Answer :

CONSTRUCTOR's are special type of methods, constructor method is executed automatically whenever a object is created or instantiated.

• Constructor: This method is executed automatically whenever object is created, this is used to set default values with respect to instance/object. The name of the constructor method is CONSTRUCTOR.
• Static Constructor: This method is executed automatically whenever object is created, this is used to set default values globally irrespective of instances/objects.The name of the static constructor is CLASS_ CONSTRUCTOR.

Question 28. What Is A Polymorphism In Ooabap ?

Answer :

Polymorphism is a concept by which the same method names will behave differently in different classes i.e each method will have it's own implementation in different classes but with the same name.

Question 29. Can We Defined A Class Without A Constructor In Ooabap ?

Answer :

 Yes, class can be created without any constructor. Default constructor will be created when we define a class without constructor.

Question 30. What Is A Friend Class?

Answer :

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

Question 31. What Is Alias?

Answer :

Instead of specifying full name of interface methods, we can assign it a name which can directly trigger.

Question 32. What Is Me Variable?

Answer :

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

Question 33. How To Create A Global Class?

Answer :

With tcode SE24.

Question 34. How To A Create Object For The Class?

Answer :

Data: ref type ref to .
Create object ref.

Question 35. How To Call A Method?

Answer :

Call method ref­>method_name .

Question 36. What Are The Differences Local & Global Classes?

Answer :

• 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).

Question 37. What Is The Difference Between Function Group And Classes?

Answer :

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

Question 38. How Many Types Of Classes Are There In Ooabap?

Answer :

• Public class
• Private class
• Final class
• Single­ton class
• Abstract class
• Persistent class
• Friend class

Question 39. How To Define A Class Locally?

Answer :

class <cl_name> definition.
Public section.
Methods: m1 importing p1 type <c>
Exporting p2 type <i>
Changing p3 type <n>
Returning p4 type <i>
Exceptions <e1>.
Protected section.
Private section.
Endclass.
Class <c1_name> implementation.
Method m1.­­­­­­
Endmethod.
Endclass

Question 40. How To Create An Object For Private Class?

Answer :

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.