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Object Oriented Design Interview Questions

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Are There Any Limitations Of Inheritance

Parking Lot Design | Object Oriented Design Interview Question

Yes, with more powers comes more complications. Inheritance is a very powerful feature in OOPs, but it has some limitations too. Inheritance needs more time to process, as it needs to navigate through multiple classes for its implementation. Also, the classes involved in Inheritance – the base class and the child class, are very tightly coupled together. So if one needs to make some changes, they might need to do nested changes in both classes. Inheritance might be complex for implementation, as well. So if not correctly implemented, this might lead to unexpected errors or incorrect outputs.

What Is Constructor Chaining

In OOPs, constructor chaining is a sequence of invoking constructors upon initializing an object. It is used when we want to invoke a number of constructors, one after another by using only an instance. In other words, if a class has more than one constructor and one of them tries to invoke another constructor, this process is known as constructor chaining. In C++, it is known as constructor delegation and it is present from C++ 11.

What Are The Solid Principles Of Object Oriented Programming

SOLID is an acronym for five object oriented design principles that make software understandable, flexible, and maintainable. SOLID stands for:

Single Responsibility: A class should have a single responsibility.

Open/Closed: Software should be open for extension and closed for modification.

Liskov Substitution: Objects in a program should be replaceable with instances of their subtypes without altering that programs correctness.

Interface Segregation: Many client-specific interfaces are better than one general-purpose interface.

Dependency Inversion: A developer should depend on abstractions, not concretions.

I cannot overstate the importance of the SOLID principles listed above. I created an entire course dedicated to learning and practicing these principles. Its one of my most popular and top-rated courses. I also have an excellent YouTube playlist for you to watch that explains the object oriented programming basics.

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Oop Why Are They So Popular

Object-Oriented Programming is a programming paradigm that emphasizes the structure of a program as well as its data. This makes it easier to read, understand, and maintain code. OOPs, are also popular because they allow multiple developers to work on the same project without accidentally affecting each others code.

What Is The Difference Between Structure And A Class

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The default access type of a Structure is public, but class access type is private. A structure is used for grouping data, whereas a class can be used for grouping data and methods. Structures are exclusively used for data, and it doesnt require strict validation, but classes are used to encapsulate and inherent data, which requires strict validation.

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What Are Static Methods

The static keyword defines methods that will exist independently of any instances created from the class. Static methods do not have access to any of the instance variables of the class. Static functions are beneficial when you need quick execution of functions that dont need other parts of the containing class.

Design Pattern Interview Questions For Senior And Experienced Level

Head First design pattern1. Give an example where you prefer abstract class over interface? tricky design interview question10 things to know about Java interfaces2. Design a Vending Machine which can accept different coins, deliver different products?design documentcode3. You have a Smartphone class and will have derived classes like IPhone, AndroidPhone,WindowsMobilePhonecan be even phone names with brand, how would you design this system of Classes4. When do you overload a method in Java and when do you override it? 5. Design ATM Machine ?lockingtransactionerror conditionboundary condition6. You are writing classes to provide Market Data and you know that you can switch to different vendors overtime like Reuters, wombat and may be even to direct exchange feed , how do you design your Market Data system.dependency injection7. Why is access to non-static variables not allowed from static methods in Javawhy non static variable are not accessible in static context8. Design a Concurrent Rule pipeline in Java?thread-safetyinstance variablesrace conditiondeadlockThreadLocal variables

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What Are The Manipulators In Oop And How It Works

Manipulators are helping functions. It is used to manipulate or modify the input or output stream. The modification is possible by using the insertion and extraction operators. Note that the modification of input or output stream does not mean to change the values of variables. There are two types of manipulators with arguments or without arguments.

The example of manipulators that do not have arguments is endl, ws, flush, etc. Manipulators with arguments are setw, setfill, setbase, setiosflags. Some other manipulators are showpos, fixed, scientific, hex, dec, oct, etc.

When Does Oop Differ From Sop

Elevator System Design | Object Oriented System Design Interview Question

When I was preparing for my OOP interview, I read a lot about the difference between OOP and SOP. I was initially confused by the terminology because they both sound like they are related to the same thing. However, OOP is a different way of thinking about programming that focuses on objects and their dependencies. SOP is a specific way of implementing OOP in a company or organization.

I think the main difference between OOP and SOP is that OOP emphasizes object-oriented design, while SOP deals with the practical aspects of implementing it in an organization. For example, SOP might focus on how to structure code so that it is easy to maintain and understand.

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Difference Between Procedural Programming And Oops

Procedural Programming
It does not have a scope for code reuse. It provides more scope for code reuse.
It follows the concept of top-down programming. It follows a bottom-up programming paradigm.
The nature of the language is complicated. It is less complicated in nature, so it is easier to modify, extend and maintain.
It is hard to modify, extend and maintain the code.

How Is An Abstract Class Different From An Interface

Interface and abstract class both are special types of classes that contain only the methods declaration and not their implementation. But the interface is entirely different from an abstract class. The main difference between the two is that, when an interface is implemented, the subclass must define all its methods and provide its implementation. Whereas when an abstract class is inherited, the subclass does not need to provide the definition of its abstract method, until and unless the subclass is using it.

Also, an abstract class can contain abstract methods as well as non-abstract methods.

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What Is Hierarchical Inheritance

In the case of a hierarchical inheritance, multiple subclasses inherit from a parent class. Hierarchical inheritance is a type of inheritance in which multiple classes are descended from a single parent or base class. For example, the fruit class can have apple, mango, banana, cherry etc. as its subclasses.

What Are The Various Types Of Constructors In C++

Object Oriented Design Interview Questions And Answers

The most common classification of constructors includes:

Default constructor: The default constructor is the constructor which doesnt take any argument. It has no parameters.


Parameterized constructor: The constructors that take some arguments are known as parameterized constructors.


Copy constructor: A copy constructor is a member function that initializes an object using another object of the same class.

classABC// Copy constructor   ABC   }

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What Is Data Abstraction And How Can We Achieve Data Abstraction

It is one of the most important features of OOP. It allows us to show only essential data or information to the user and hides the implementation details from the user. A real-world example of abstraction is driving a car. When we drive a car, we do not need to know how the engine works we only know how ECG works.

There are two ways to achieve data abstraction

What Is An Exception

An exception can be considered as a special event, which is raised during the execution of a program at runtime, that brings the execution to a halt. The reason for the exception is mainly due to a position in the program, where the user wants to do something for which the program is not specified, like undesirable input.

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Problem : Design A Vending Machine In Java

You need to design a Vending Machine which follows the following requirements:1. It should accepts coins of 1,5,10,25, 50 Cents, i.e., penny, nickel, dime, and quarter as well as 1 and 2 dollar note

2. Allow user to select products like CANDY, SNACK, NUTS, Coke, Pepsi, Soda

3. Allow users to take a refund by canceling the request.

4. Return the selected product and remaining change if any

5. Allow reset operation for vending machine supplier

You can try solving the problem on your own before looking at the solution. At least come up with classes and method names and relationship between classes. Preparing a UML diagram is bonus.

What Are The Limitations Of Oops

Parking Lot System Design Interview Question and Answer in Java| Object Oriented Design| Code Decode
  • Larger Program size Programs can become lengthy if written using OOps concepts compared to procedure-oriented programming.
  • Slower execution As the number of lines of code to be executed is more comparatively, the execution time is also more.
  • Not suitable for all types of Problems.
  • Testing time is also higher for OOP Solutions.
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    What Is Meant By Exception Handling

    No one wants its software to fail or crash. Exceptions are the major reason for software failure. The exceptions can be handled in the program beforehand and prevent the execution from stopping. This is known as exception handling.So exception handling is the mechanism for identifying the undesirable states that the program can reach and specifying the desirable outcomes of such states.Try-catch is the most common method used for handling exceptions in the program.

    What Are Some Advantages Of Using Oops

    • OOPs is very helpful in solving very complex level of problems.
    • Highly complex programs can be created, handled, and maintained easily using object-oriented programming.
    • OOPs, promote code reuse, thereby reducing redundancy.
    • OOPs also helps to hide the unnecessary details with the help of Data Abstraction.
    • OOPs, are based on a bottom-up approach, unlike the Structural programming paradigm, which uses a top-down approach.
    • Polymorphism offers a lot of flexibility in OOPs.

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    How To Come Up With Object Oriented Design Solutions

    The typical OOD question used to test your object oriented programming skills with a real solution will give you a vague problem like:

    Design a game of blackjack

    Design an URL shortener service

    Design an ATM

    Design a two-player chess game

    Design a restaurant

    Design a parking lot

    Design an online stock brokerage

    The problem may also have some constraints to give you a better idea of the solution the interviewer expects. For example, you could limit the blackjack game to a dealer and one player. Pay attention to these constraints because they will keep you from overthinking your solution and spending a lot of time building a solution that doesnt fit the problem. Ive authored a top-rated object oriented design course covering the SOLID principles of object oriented design that can help with this.

    Even with some practical constraints, you will still have a lot of work ahead of you. To make this process easier, you can use these steps to narrow down the functionality you need to create:

    1. Ask questions. If you dont completely understand the requirements, ask some questions. I actually encourage you to ask questions to clarify both the interviewers and your own assumptions about the problem, so you and the interviewer agree. This will not only show that you are a responsible problem solver but also detail-oriented in your approach to thinking about the requirements.

    Can the candidate ask the right questions to gather requirements about the problem?

    What Are The Levels Of Data Abstraction

    Object Oriented Analysis and Design 2010

    There are three levels of data abstraction:

    • Physical Level: It is the lowest level of data abstraction. It shows how the data is actually stored in memory.
    • Logical Level: It includes the information that is actually stored in the database in the form of tables. It also stores the relationship among the data entities in relatively simple structures. At this level, the information available to the user at the view level is unknown.
    • View Level: It is the highest level of data abstraction. The actual database is visible to the user. It exists to ease the availability of the database by an individual user.

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    Oop: What Are The Benefits

    There are many benefits to using Object Oriented Programming when programming. OOP can help reduce code duplication, make code more readable and maintainable, and improve overall development efficiency. Additionally, OOP can help you design more effective algorithms and architectures.

    When I first started learning about OOP, I found that it made a lot of sense. I found that I could easily see how my code was organized and how it worked together. This made it much easier for me to debug and troubleshoot problems.

    Additionally, I found that I could easily create reusable components and classes. This made my code more robust and easier to maintain. Overall, I believe that using OOPs has been a huge benefit for me in my programming career. I strongly recommend anyone looking to improve their skills in this area consider adopting OOPs into their development process.

    Object Oriented Programming Interview Questions

    The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed’s data and insights to deliver useful tips to help guide your career journey.

    Interview preparation includes researching the company you will be interviewing with, practicing with a mock interview and reviewing commonly asked questions. Interviewing for an object-oriented programming position is no exception. There are many object-oriented interview questions you may be asked in an interview for this type of position. In this article, we will provide 50 object-oriented programming interview questions and some example answers to help you prepare for your interview.

    Video: Top 6 Common Interview Questions and Answers

    Jenn, an Indeed Career Coach, breaks down the intentions behind employer’s questions and shares strategies for crafting strong responses.


    These questions demonstrate your level of understanding of object-oriented programming, or OOPs.

    • What is object-oriented programming ?

    • What are the basic concepts of OOPs?

    • What is an object?

    • Explain the difference between class and structure

    • What is a constructor?

    • What is an interface?

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    How To Design Facebook’s Newsfeed What Kind Of Algorithm Will You Use

    The newsfeed is an important part of Facebook which allows a user to see what’s happening around his world which includes friends and families, the pages he has liked, the group he has followed, and of-course the Facebook Ads.

    The job of the Newsfeed algorithm is to show messages which are most important for the user and which can generate high engagement. Obviously, messages from friends and family should take priority. If you feel not going anywhere and stuck, you can follow the solution on System Design Interviews: Grokking the System Design Interview.

    How Do You Design A Chat Application Like Whatsapp Or Facebook Messenger

    OOPS Interview Questions and Answers | Object Oriented Programming Interview Questions C#

    You have surely used WhatsApp and Facebook, right? No? If not let me tell you that a chat application allows you to send messages to your friend. It’s a point to point connection. You keep a friend list and see their status and chat them. In WhatsApp, you can also connect groups but that is for advanced and experienced developers. At a minimum, you should provide a design to keep a friend list and send and receive messages from them.

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    Name Any Seven Widely Used Oop Languages

    There are various OOP languages but the most widely used are:

    • All predefined types are objects
    • All user-defined types are objects
    • All operations performed on objects must be only through methods exposed to the objects.

    Java is not a pure object-oriented programming language because pre-defined data types in Java are not treated as objects. Hence, it is not an object-oriented language.

    What Is An Interface

    An interface refers to a special type of class, which contains methods, but not their definition. Only the declaration of methods is allowed inside an interface. To use an interface, you cannot create objects. Instead, you need to implement that interface and define the methods for their implementation.

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    How Does C++ Support Polymorphism

    C++ is an Object-oriented programming language and it supports Polymorphism as well:

    • Compile Time Polymorphism: C++ supports compile-time polymorphism with the help of features like templates, function overloading, and default arguments.
    • Runtime Polymorphism: C++ supports Runtime polymorphism with the help of features like virtual functions. Virtual functions take the shape of the functions based on the type of object in reference and are resolved at runtime.

    How To Prepare For Low

    Object Oriented Analysis and Design 2012

    Software Developers need to learn Low-Level Design not only to crack the Interviews but also to build modular, extensible, reusable, and maintainable software. It is the thought process that developers need to develop to effectively build the software from a set of requirements.

    Here is the list of things that a software developer needs to learn for LLD Interviews:

    Apart from these, there are well-known principles such as favouring composition over inheritance, Encapsulating what varies, Striving for loosely coupled classes, etc.

    • UML Diagrams: UML is an acronym that stands for Unified Modeling Language and is a standard for modelling, visualizing, and documenting the artefacts of software systems. It is not a programming language but a tool to visually depict different types of diagrams that can be useful for building the software.
    • There are 14 different types of UML Diagrams and these 14 diagrams are classified into 2 high-level groups.
    • Structural Diagrams: They represent the static view of the system. Class Diagram, Composite Structure Diagram, Object Diagram, Component Diagram, Deployment Diagram, Profile Diagram, and Package Diagram are part of Structural Diagrams.
    • Behavioural Diagrams: They represent the dynamic view of the system. Activity Diagram, State Machine Diagram, Use Case Diagram, Interaction Overview Diagram, Timing Diagram, Sequence Diagram, and Communication Diagram are part of Behavioral Diagrams.

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