Grokking The Object Oriented Interview

Design An Online Stock Brokerage System

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

A good answer would cover these points:

Watchlists: How would the system handle watchlists created by the user to save/monitor specific stocks?
Transaction Types: How would the system handle different transaction types, e.g. stop loss and stop limit order? What types would be supported?
Stock Lots: How will the system differentiate between different lots of the same stock for reporting purposes if a user has bought the same stock multiple times?
Reporting: How will the system generate reports for monthly, quarterly, and annual updates?

Object Oriented Analysis And Design

Object Oriented Analysis and Design is a structured method for analyzing and designing a system by applying object-oriented concepts. This design process consists of an investigation into the objects constituting the system. It starts by first identifying the objects of the system and then figuring out the interactions between various objects.

The process of object oriented analysis and design can be described as:

Identifying the objects in a system.

Defining relationships between objects.

Establishing the interface of each object.

Making a design, which can be converted to executables using object-oriented languages.

We need a standard method/tool to document all this information for this purpose we use UML. UML can be considered as the successor of object-oriented analysis and design. UML is powerful enough to represent all the concepts that exist in object-oriented analysis and design. UML diagrams are a representation of object-oriented concepts only. Thus, before learning UML, it is essential to understand object-oriented concepts.

Lets find out how we can model using UML.

Oo Analysis And Design

OO Analysis and Design is a structured method for analyzing and designing a system by applying object-oriented concepts. This design process consists of an investigation into the objects constituting the system. It starts by first identifying the objects of the system and then figuring out the interactions between various objects.

The process of OO analysis and design can be described as:

Identifying the objects in a system

Defining relationships between objects

Establishing the interface of each object and,

Making a design, which can be converted to executables using OO languages.

Letâs find out how we can model using UML.

VA
Create

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Categories Java Design Patterns

Below is the list of top Design Pattern Interview Questions and answers at your rescue. The difference between VO and JDO is that the JDO is a persistent technology that competes against entity beans. It allows to create POJO and persevere them to the database. DAO interface describes the standard actions to be performed on a model object. The new filter can be added at any time without affecting the clients code. Filter pattern provides central control with loosely coupled handlers.

Design A Library Management System

Grokking The Object Oriented Design Interview

A Library Management System is a software built to handle the primary housekeeping functions of a library. Libraries rely on library management systems to manage asset collections as well as relationships with their members. Library management systems help libraries keep track of the books and their checkouts, as well as membersâ subscriptions and profiles.

Library management systems also involve maintaining the database for entering new books and recording books that have been borrowed with their respective due dates.

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The Approach To Ood Interview Questions:

In Object Oriented Design questions, interviewers are looking for your understanding of the nuances of complex problems and your ability to transform the requirements into comprehensible Classes.

In fact, OOD questions generally will all follow a very similar pattern. You will be provided with a vague problem and a set of constraints for a system to design, and very little else. It is then up to you, the candidate, to figure out the level of solution that the interviewer is looking for, what kind of functionality will be needed, and come up with a workable solution.

Interviewers are looking for one main thing: finding the right balance between a solution that works immediately and is also adaptable to change in the future.

To simplify things, you can take the following approach for any OOD question you encounter:

Clarify the requirements: Make sure you understand the expectations of the interviewer. Ask clarifying questions if at all necessary the interviewer will not mind, and will likely appreciate it. For example, are you looking for me to demonstrate the structure of a solution, or to fully implement it? Doing this here will take about 510 seconds, but save tremendous amounts of time later.

Identify key Objects: Now, identify all the objects that will play a role in your solution. For example, if youre designing a parking lot, these will be things like vehicles, parking spots, parking garages, entrances, exits, garage operators, etc.

Explain The Advantage Of Chain Of Responsibilities Pattern And When It Is Used

Some of them are read-through, write-through, cache-aside, and time-based. Virtual proxies are used to instantiate the expensive object. The proxy manages the lifetime of the real subject in the implementation.

They are only templates that describe how to solve a particular problem with great efficiency. To know more about design patterns basics, refer Introduction to Design Patterns. A GUI Game designed using Java in the advanced programming domain involving various concepts OOPs, interface, error handling, multithreading, etc. The objective of the game is to defend the house from zombies using various plants as a defense arsenal through different levels. If the zombies are able to reach the house, you fail the level and have to play the level again.

It also identifies the relationships which led to the simplification of the structure. Both factory and abstract factories are creational design patterns. The major difference between these two is, a factory pattern creates an object through inheritance and produces only one Product.

Thread-safe Singleton can be written by writing singleton using double-checked locking. There are many ways to write a Thread-safe singleton in Java. In case we need to add the responsibilities dynamically to the individual object without affecting other objects. When an object requires to utilize an existing class with an incompatible interface.

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The Follow Up Questions

With above basic construct in place and hopefully some time left in the interview, we’re expecting some follow up questions from the interviewer. The purpose of these questions is to see how well you understand writing scalable code.

Are you locking yourself into a corner, or are you able to identify opportunities for scalability already? How well are you communicating your thinking and planning process?

I intentionally left some room for improvement in the code snippets above. Right now in our design, if all rooms for small dogs are taken, the customer is sent away. To improve the user experience, we want to add the ability to have small dogs occupy medium sized rooms as well.

class Hotel     return roomID  }  private func getRooms ->  Void)     if dog.size == .medium       if largeRooms.keys.count <  largeRoomsCount     }    if dog.size == .small       if mediumRooms.keys.count <  mediumRoomsCount       if largeRooms.keys.count <  largeRoomsCount     }  }}

A major improvement of our design, is to define the access level of a function. We mark functions as public, if we want consumers to be able to access it.

In the new design we’re going to try to get a roomID from a private method. This function is not async. It’s just written with a closure, because we’re returns a reference. That’s the inout equivalent of returns.

If we have rooms, then we want to create an ID, assign the dog to that room and lastly return it to the consumers.

class Hotel

Even Seasoned Developers Grapple With Object Oriented Design Interview Questions

Parking Lot Design | Object Oriented Design Interview Question

Due to the unstructured nature of object oriented design interviews, theres no standard answer. As a result, many developers find them tough.

And thats where FAANG interview prep materials come in.

This post contains affiliate links. I may receive compensation if you buy something. Read my disclosure for more details.

Today were reviewing the Grokking the Object Oriented Design Interview course on Educative.

This object oriented design course was designed by hiring managers of Google, Facebook, Amazon and Microsoft. It contains handpicked case studies that are regularly asked at FAANG interviews.

In addition, the course enables engineers to handle various object oriented design scenarios with confidence.

An excellent set of problems, I have been asked Parking Lot and Flight Reservation system in two interviews. This course helped me brush up object oriented analysis techniques that I had almost forgotten. Thanks guys for this content.

Billy Hu, Software Engineer at Microsoft

Lets take a closer look at what this course has to offer.

Looking for some more FAANG interview courses? Check out our review of Grokking the System Design Interview.

This FAANG interview prep course is separated into two sections:

Object Oriented Design and UML

Object Oriented Design Case Studies

Expectations From The Candidates

In the LLD Interviews, they will judge you on your knowledge of creating modular, flexible, maintainable and reusable software, by applying Object-oriented Design Principles and Design Patterns. These questions are about demonstrating that you understand how to create elegant, maintainable object-oriented code. These questions are unstructured and open-ended and they don’t have a standard answer.

Design A Movie Ticket Booking System

Interviewers would be keen on seeing the following points in your answer:

Duplication: How are you handling instances, such as the same cinema having multiple cinema halls showing different movies simultaneously? Or the same movie being shown at different times in the same cinema/hall?
Payment Handling: What would be the process for a user to purchase a ticket?
Selection: How would user a pick a seat, ensuring its not already booked by someone else?
Price Variances: How would discounted pricing be considered? For example, for students or children.

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Grokking The Object Oriented Design Interview Github

Contribute to tssovi/grokking-the-object-oriented-design-interview development by creating an account on GitHub.

Let’s make an object-oriented design for a multi-floor parking lot. We use cookies to ensure you get the best experience on our website.

Grokking the Object Oriented Design Interview has great examples for building systems from Object Design perspective. Examples like âBuild a LinkedInâ, âBuild a Facebookâ will give you ideas of what objects will be needed and how the objectsâ relationship will be.

Grokking System And Object Oriented Design Interview

Structural Design Patterns

Lets you save and restore the previous state of an object without revealing the details of its implementation. Lets you traverse elements of a collection without exposing its underlying representation . Turns a request into a stand-alone object that contains all information about the request. This transformation lets you pass requests as a method arguments, delay or queue a requests execution, and support undoable operations.

Strategy pattern deals with HOW an object performs a certain task, whereas the state design pattern deals with what an object is. The intercepting filter design pattern is used to intercept and manipulate a request and response before and after the request processing. Filters perform the authentication/ authorization/ logging or tracking of request and then forward the requests to corresponding handlers. Lets have a look at some basic entities of Intercepting design pattern.

This book pairs well with the course Grokking the Coding Interview on Educative.io. Command design pattern is useful to abstract the business logic into discrete actions which we call commands. These command objects help in loose coupling between two classes where one class shall call a method on other class to perform a business operation. Structural design patterns show us how to glue different pieces of a system together in a flexible and extensible fashion.

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Design Amazon / Flipkart

Beyond the basic functionality , interviewers will be looking for the following:

Discoverability: How will the buyer discover a product? How will the search surface results?
Cart & Checkout: Users expect the cart and checkout to behave in a certain way. How will the design adhere to such known best practices while also introducing innovative checkout semantics like One-Click-Purchase?
Payment Methods: Users can pay using credit cards, gift cards, etc. How will the payment method work with the checkout process?
Product Reviews & Ratings: When can a user post a review and a rating? How are useful reviews tracked and less useful reviews de-prioritized?

Requirements And Goals Of The System

Card reader: to read the users ATM cards.

Keypad: to enter information into the ATM e.g. PIN.cards.

Screen: to display messages to the users.

Cash dispenser: for dispensing cash.

Deposit slot: For users to deposit cash or checks.

Printer: for printing receipts.

Communication/Network Infrastructure: it is assumed that the ATM has a communication infrastructure to communicate with the bank upon any transaction or activity.

The user can have two types of accounts: 1) Checking, and 2) Savings, and should be able to perform the following five transactions on the ATM:

Balance inquiry: To see the amount of funds in each account.

Deposit cash: To deposit cash.

Deposit check: To deposit checks.

Withdraw cash To withdraw money from their checking account.

Transfer funds: To transfer funds to another account.

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Section : Object Oriented Design And Uml

Starting with the basics, youll get a refresher on some key object oriented programming concepts:

Objects Class Encapsulation

And from there it covers:

Object Oriented Analysis and Design identify, define, establish, create
Unified Modeling Language visualizing & documenting software system by using a collection of diagrams
Use Case Diagrams what the system does from the user point of view
Class Diagram describe the responsibilities of a system
Sequence Diagram detailed flow for a specific use case
Activity Diagrams model the flow of control from activity to activity

Object Oriented Design Interview Questions Pdf

Ace the JAVASCRIPT INTERVIEW Grokking the System Design Interview course review || educative.io

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The approach to OOD interview questions: In Object Oriented Design questions, interviewers are looking for your understanding of the nuances of complex problems and your ability to transform the requirements into comprehensible Classes. In fact, OOD questions generally will all follow a very similar pattern.

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Design Amazon / Flipkart: Build An Online Shopping Platform

An interviewer will be looking for the basic functionality of necessary features like signup and logic. They will also be assessing the following:

Discoverability: How will a buyer be able to discover a product? How will their search display results?
Cart & Checkout: Users expect a checkout process and virtual to behave a certain way. How will the frontend design adhere to these best practices while also implementing new or innovative checkout semantics?
Payment Methods: Users should be able to pay with credit cards, gift cards, etc. How will the payment method work? What new functionalities can be added to improve payment processes?
Product Reviews & Ratings: Ratings improve online shopping experiences. When and how can a user post a review or a rating? How will you track useful reviews and de-prioritize less useful reviews?

Section : Object Oriented Design Case Studies

There are 16 design case studies:

Library Manangement

This section sets the parameters of the project such as:

floors entrances & exits parking tickets payment types

vehicle capacity parking spots with vehicle size variance

vehicle types hourly pricing structure

And much more.

This section addresses main Actors in the system such as:

Admin responsible for modifying parking lot specs

Customer receive and pay for parking ticket

Parking Attendant assist customers with their tasks

System display messages on info panels, assign and remove vehicles

And from there, youll examine the top use cases for parking lot object oriented design:

parking floor add, remove, edit
parking spot add, remove, edit
take & scan ticket

iv. Activity Diagrams

Activity Diagrams offer a series of potential activities and results based on those activities.

For example, this diagram observes the activity of the ticket being paid:

As you can see, many activities are straightforward.

For example, if the customer inserts the credit card into the card reader, the next step is for the system to read the credit card details.

But there are other activities that have multiple potential outcomes. For example, Payment successful? can either be successful or produce an error. This will alter the processes moving forward.

v. Code

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Design Facebooka Social Network

A social network like Facebook requires many relationships and interconnected networks. It should allow for a lot of variance, personalization, and recommendation systems using ML components. Your answer should ideally discuss:

Discoverability: How will users search for other users profiles? Will there be ML components in place for this?
Following: How will users follow or unfollow other users without becoming a direct connection?
Groups / Pages: How can members create groups, pages, and profiles?
Privacy: How does the system handle privacy lists with certain content to be displayed only to specified connections?
Alerts: How will users be notified for pre-selected events?