Top 45 OOPs Interview Questions by Team MTA India

Top 45 OOPs Interview Questions by Team MTA India

Object-oriented programming (OOP) is a computer programming model that organizes software design around data, or objects, rather than functions and logic. An object can be defined as a data field that has unique attributes and behavior.

Q1. What does the word OOPs mean?

Answers. OOPs mean Object Oriented Programming System. The programming paradigm is defined using objects. Things can be seen as real-world examples of  businesses like class, with certain features and behaviors.

Q2. What is the need for OOPs?

Answers. There are many reasons why OOP is so popular, but the most important of these are:

  1. OOPs help users to understand the software easily, even when they can use it.
  2.  With OOPs, learning, understanding, and coding increases significantly.
  3.  Even large software can be written and managed easily using OOPs.

Q3. What are the main languages ​​of  Object-Oriented Programming?

Answers. The programming languages ​​that use and follow the Object-Oriented Programming or OOP paradigms are known  as Object-oriented programming languages. Some of the major languages ​​of Object-Oriented Programming  include:

• Java

• C ++

• Javascript


Many more.

Q4. What are the other paradigms of the system other than OOPs?

Answers. Programming paradigms refer to the process of classifying programming languages ​​based on their characteristics. There are mainly two types of Programming Paradigms:

• Imperative Programming Paradigm

• Declarative Programming Paradigm

Now, these paradigms can be categorized based on:

1. Key Planning Paradigm: A key program focuses on how to use a logical system and defines control flow as statements that change the status of the system. This can also be edited by:

a) Procedural Programming Paradigm: Procedural planning specifies the steps a system must take to achieve the desired situation, usually read in sequence from top to bottom.

b) Object-Oriented Programming or OOP: Object-oriented programming (OOP) classifies programs as objects, containing specific data and having certain behaviors.

c) Integrated Planning: A parallel planning paradigm divides a task into smaller tasks and focuses on performing them simultaneously.

2. Declarative Programming Paradigm: The advertising program focuses on WHAT to start and explain the thinking of the program, but not the detailed control flow. The declaration paradigm can be divided into:

a) Logical Programming Paradigm: A logical planning paradigm based on a well-thought-out thinker, referring to a set of sentences that express facts and rules about how to solve a problem.

b) Functional Programming Paradigm: A functional program is a paradigm program in which programs are developed using and integrating tasks.

c) Database Programming Paradigm: A site editing model used to manage data and organize information such as fields, records, and files.

Q5. What does Structured Programming mean?

Answers. Structured Programming refers to a planning process that consists of a fully organized control flow. Here structure refers to a block, which contains a set of rules, and has a straight flow, such as (if / then / another), (then again), block structures, and sub-processes.

Almost all program paradigms include Systematic Planning, which includes the OOPs model.

Q6. What are the main features of OOPs?

Answers. OOPs or Object Oriented Programming mainly consists of the four components below, and make sure you do not miss any of the following:

• Encapsulation

• Inheritance

• Polymorphism

• Abstraction

Q7.What are some of the benefits of using OOPs?

Answers. OOPs are very helpful in solving the level of complex problems.

• Extremely complex systems can be created, managed, and easily maintained using an object-focused system.

• OOPs, encourage code reuse, thereby reducing inefficiency.

• OOPs also help to hide unwanted information with the help of Data Abstraction.

• OOPs, based on a direct approach, unlike the Structural programming paradigm, which uses a direct approach.

• Polymorphism provides a lot of flexibility in OOPs.

Q8. Why is OOP so popular?

Answer. OOPs, the editing paradigm is considered the best style of editing. It not only helps to write a complex piece of code easily but also allows users to easily manage and maintain it. Not only that, the main pillar of OOPs – Data Extraction, Ecapsulation, Inheritance, and Polymorphism, makes it easier for program planners to solve complex situations. Because of this, OOPs are very popular.

Q9. What is a class?

Answer. A class can be understood as a template or system, consisting of specific values, known as member or member data, and a set of rules, known as behaviors or functions. So when something is created, it automatically picks up the data and activities defined in the class.

The classroom is therefore a template or blueprint for objects. And one can build as many things as one wishes according to the class.

For example, first of all, a car model is created. Then many car units were built based on that model.

Q10. What is an object?

Answer. The object refers to a class model, which contains the example of the members and behavior described in the class template. In the real world, lumbering elephants are exposed by the aggression of speeding midgets. So things take place and have certain behaviors.

For example, a car.

Q11. What is encapsulation?

Answer. One can visualize Encapsulation as a way to put everything needed to do a job, inside a capsule and present that capsule to the user. Which is to say that with Encapsulation, all the required data and methods are compiled together and all unnecessary details are hidden from the average user. Encapsulation is therefore a process of binding members of the data and systems to perform a particular function, without disclosing unnecessary details.

Encapsulation can be defined in two different ways:

Encryption: Encapsulation is the process of encrypting unwanted information, such as limiting access to any part of an object.

 Data binding: Encapsulation is the process of combining data and methods of members together, as a class.

Q12. What is Polymorphism?

Answer. Polymorphism is made up of two words – “poly” meaning “many”, and “morph” meaning “ammo”. Polymorphism, therefore, refers to something that has many facets.

In OOPs, Polymorphism refers to the process by which a particular code, data, method, or object behaves differently under different circumstances or circumstances. Integrated polymorphism and Run time polymorphism are two types of polymorphisms in OOPs languages.

Q13. What is Compile time Polymorphism and how is it different from Runtime Polymorphism?

Answer. Complete Time Polymorphism: A composite polymorphism, also known as Static Polymorphism, refers to the type of Polymorphism that occurs during compilation. This means that the manufacturer decides which shape or value should be taken by the business in the picture.


// In this program, we will see how many jobs are created under the same name,

// but the president decides which function it will cost most easily during the actual assembly.

classCompileTimePolymorphism {

// The first method with the name add

publicintadd (int x, int y) {

returns + y;


// 2nd named way to add

publicintadd (int x, int y, int z) {

returnx + y + z;


// 3 word called add

publicintadd (double x, int y) {

replace (int) x + y;


// Method 4 with additional name

publicintadd (int x, double y) {

replace x + (int) y;



classTest {

publicstaticvoidmain (Series [] args) {

CompileTimePolymorphism Demo = newCompileTimePolymorphism ();

// In the statement below, the Consolidator looks at the types of disputes and decides to name 1 method

System.out.println (demo.add (2,3));

// Similarly, in the statement below, the compiler calls method 2

System.out.println (demo.add (2,3,4));

// Similarly, in the statement below, the compiler calls method 4

System.out.println (demo.add (2,3.4));

// Similarly, in the statement below, the compiler calls method 3

System.out.println (demo.add (2.5,3));



In the example above, there are four versions of the appendix. The first method takes two parameters and the second takes three. In the third and fourth modes, there is a change in the parameter setting. The coordinator looks at the route signature and decides which route to request a specific route call during the meeting.

Runtime Polymorphism: Runtime polymorphism, also known as Dynamic Polymorphism, refers to the type of Polymorphism that occurs during performance. Which means it can’t be determined by the producer. So any position or value to be taken depends on the execution. Hence the name Runtime Polymorphism.


classAnyVehicle {

publicvoidmove () {

System.out.println (“Any car should go !!”);



classBikeextendsAnyVehicle {

publicvoidmove () {

System.out.println (“A bike can go with it !!”);



classTest {

publicstaticvoidmain (Series [] args) {

AnyVehicle vehicle = newBike ();

// In the statement above, as you can see, the object car is of the AnyVehicle type

// But the result of the statement below will be “The bike can go with it !!”,

// because the actual use of the ‘vehicle’ item is determined during the vehicle.smission ();

car = newAnyVehicle ();

// Now, the result of the statement below will be “Any car should go !!”,

car.mute ();



As the call method is determined during operation, as shown in the code above, this is called runtime polymorphism.

Q14. How does C ++ support Polymorphism?

Answer. C ++ is an object-oriented programming language that supports Polymorphism and:

• Integrate Time Polymorphism: C ++ supports integration time polymorphism with the help of features such as templates, functionality, and default arguments.

• Runtime Polymorphism: C ++ supports Runtime polymorphism with the help of features such as visual functions. Visual tasks take the form of tasks based on the type of reference object and are solved during operation.

Q15. What does it mean to inherit?

Answer. The word “inheritance” means “hereditary possession or inheritance.” In an object-focused system, it inherits the process by which an object or class (referred to as a child) is created using the definition of another object or category (referred to as a parent). The asset not only helps to keep usage simple but also helps to simplify reuse of code.

Q16. What is Abstraction?

Answer. If you are a user, and you have a problem statement, you do not want to know how the software components work, or how they are used. You just want to know how software solves your problem. Abstract is a way of hiding unnecessary information from what is needed. It is one of the main features of OOPs.

For example, consider a car. You need to be able to drive only the car, not just the wires in it. This is obtained using Abstraction.

Q17. How much memory does the class take?

Answer. Classes do not eat any memory. They are simply a blueprint for creation. Now when things are created, they start with class members and methods and as a result eat up memory.

Q18. Is it always necessary to build objects from the classroom?

Answer. No. An object needs to be created if the foundation phase has consistent mechanisms. But if the classroom has fixed structures, things do not have to be created. You can call the class route directly on this, using the class name.

Q19.  What is a builder?

Answer. Builders are special methods whose names are like class name. Builders serve a specific purpose of presentation.

For example, suppose there is a class called “MyClass”, where you verify this class, passing the syntax:

MyClassmyClassObject = new MyClass ();

Now here, the “new” keyword – MyClass (), is the creator of this category. This will help integrate member data with methods and assign it to my class item.

Q20.  What are the different types of builders in C ++?

Answer. The most common categories of builders include:

Automatic Builder: The default builder is a builder that does not take any conflicts. It has no parameters.

Category ABC


int x;

ABC ()


       x = 0;



Parameter Builder: Builders who take on certain issues are known as design builders.

Category ABC


   int x;

ABC (int y)


       x = y;



Copy Builder: A copywriter is a member who introduces an object using another object of the same category.

Category ABC


int x;

ABC (int y)


       x = y;


// Copy builder

ABC (ABC abc)


       x = abc.x;



Q21. What is a copyist?

Answer. Copy Builder is a type of builder, whose purpose is to copy something in another. It means that the copyright maker will combine the object and its values ​​into one, as long as both objects are at the same level.

Q22. What is a waste?

Answer. Unlike architects, who invent things and define their location, Destroyers have special methods. But destroyers release resources and memory that stays the thing. Destroyers are automatically named when an object is destroyed.

Q23. Is the category and structure the same? If not, what is the difference between a classroom and a building?

Answer. No, category and structure are not the same. Although they are similar, there are differences that make them different. For example, structure is stored in stack memory, while class is stored in bulk memory. Also, Data Abstraction cannot be achieved with the help of structures, but with class, Abstraction is widely used.

Q24.Describe Inheritance by example?

Answer. Assets are one of the major components of an object-focused system, in which an entity acquires certain assets and conduct in another entity and makes it its own. The asset helps to develop and facilitate the reuse of code.

Let me tell you about a typical example. Let’s take three different cars – acar, a truck, or a bus. These three are quite different from each other in that they have certain characteristics and behaviors. But in all three, you will find common elements, such as steering wheel, accelerator, clutch, brakes, etc. Although these features are used in a variety of vehicles, they still have some common features in all vehicles. This is achieved by inheritance. The car, truck, and bus are all inherited assets such as steering wheel, accelerator, clutch, brakes, etc., and are used as their own. Because of this, they did not need to build these components from the beginning, thus facilitating the reuse of code.

Q25.  Are there Legacy restrictions?

Answer. Yes, more power comes with a lot of problems. Inheritance is a very strong factor in OOPs, but it has some limitations as well. Assets need more time to process, as they need to move around more classes in order to work. Also, the classes involved in Heritage – the foundation phase and the children’s class, are highly integrated. So if a person needs to make some changes, he may need to make adjustments in both stages. Inheritance can be difficult to use, too. So if it is not done properly, this can lead to unexpected mistakes or bad consequences.

Q29. What is an interface?

Answer. Communication refers to a specific type of class, which contains methods, but not their definition. The only way ads are allowed within the interface. Using the interface, you can not create objects. Instead, you need to use that interface and explain how they are made.

Q30. What does the shape of a polymorphism mean?

Answer. The Static Polymorphism is better known as the Compile time polymorphism. A static polymorphism is a feature in which an object is connected to a relevant function or operator based on values ​​during the integration period. Standing Polymorphism or Integration Period can be accessed using the Overloading or User Filling Method.

Q31. What does dynamic polymorphism mean?

Answer. Dynamic Polymorphism or Runtime polymorphism refers to the type of Polymorphism in OOPs, where the actual use of a function is determined during action or performance. A dynamic or timely polymorphism can be achieved with the help of cross-path.

Q32. What is the difference between overweight and overweight?

Answer. Overloading is a feature of the integration time polymorphism where a business has multiple uses with the same name. For example, overload mode and Operator overload.
Although Uninstallation is a feature of the polymorphism of the operating period where the business has the same name, its use changes during implementation. For example, How to extract Picture.

Q33. How is data extraction done?

Answer. Data extraction is done with the help of invisible methods or invisible classes.

Q34. What is an abstract class?

Answer. The abstract class is a special class that contains subtle methods. The importance of the invisible category is that the invisible methods within them are not used and are only declared. As a result, when a subclass inherits an invisible class and needs to use its own invisible methods, it needs to define and apply them.

Q35. How is the invisible phase different from the visible connector?

Answer. The visual connector and the ambiguous category are both special types of classes that contain only advertising methods and not their use. But the interface is completely different from the invisible class. The main difference between the two is that, when using a virtual connector, the subclass must define all its methods and provide its own implementation. Even if the abstract class is inherited, the subclass does not need to define its invisible form, unless used by the subclass.
Also, the abstract category may contain abstract methods and non-abstract methods.

Q36. What are access details and why are they important?

Answer. Accessibility specifications, as the name implies, are special types of keywords, used to control or specify access to businesses such as categories, methods, etc. Some of the access specifications or access editors include “private”, “public”, etc. access specifications also play a key role in achieving Ecapsulation – one of the key features of OOPs.

Q37. What is different?

Answer. The exception can be considered a special event, which is raised during the execution of the program, which suspends execution. The reason for the variance is due to a system stop, where the user wants to do something when the system is not specified, such as unwanted inputs.

Q38. What does different management mean?

Answer. No one wants its software to fail or crash. The exception is the main reason for the software failure. The exceptions can be processed in advance and prevent configuration. This is known as a separate administration. Separate management is therefore a way of identifying unwanted contexts that the system can access and specifying the desired outcomes for those regions. Try-catch is a widely used method of managing different systems.

Q39.What does waste collection in OOPs mean?

Answer. An object-focused system revolves around things like business. Each item consumes memory and can have multiple classroom items. So if these items and their memory are not handled properly, that could lead to other memory-related errors and the system may fail.
Garbage collection refers to this memory system in the system. With garbage collection, unwanted memory is released by removing unwanted items.

Q40. What is Garbage Collection (GC)?
Answer. GC is the implementation of automatic memory management. Garbage collector empties trash cans.

Q41. Distinguish between class and method.
Answer. Class Method
A classroom is a template that combines code and data into one unit. Classes contain modes, variables, etc.

Q42. Distinguish between the invisible phase and the visible connector?

Answer. Basis for comparing Abstract Class Interface Ways Can Be Invisible And Other Ways Only Visible Ways Final Variables May contain the final and non-final variables The variable variables declared as default
Access to Membership Can be private, public, etc. in the public by default
Usage Can Provide the use of an invisible connector Unable to provide the use of an invisible section

Q43. What is the ultimate flexibility?

Answer. Variable its value does not change. It always refers to the same thing with immovable property.

Q44. What is exception?
Answer. The exception is the type of notification that interferes with the normal operation of the system. The exception gives the error pattern and transfers the error to a different manager for resolution. The status of the system is maintained as soon as the variance is raised.

Q45.What is a exception handling?
Answer. Respectful management in Object-Oriented Programming is a very important concept used to manage errors. A separate holder allows errors to be thrown and caught and use the middle method to resolve them.

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