Top 250 Design Patterns Interview Questions and Answers

Objects generated after TMG creation in SAP ABAP

• After creating a TMG (Table Maintenance Generator), a function group is generated.

• The function group contains function modules for maintenance screens, list displays, and authorization checks.

• A maintena...read more

A factory is responsible for creating and managing objects, while a service is responsible for providing specific functionality or performing tasks.

• A factory is used to create and initialize objects, often based on certain parameters or configuration...read more

Singleton design pattern ensures only one instance of a class is created and provides global access to it.

• Create a private constructor to prevent direct instantiation

• Create a private static instance of the class

• Provide a public static method to acces...read more

A factory is a design pattern that provides an interface for creating objects of a certain class.

• A factory encapsulates the object creation logic and hides it from the client.

• It allows the client to create objects without knowing the specific class o...read more

Design a snake game

• Use a 2D array to represent the game board

• Keep track of the snake's position and direction

• Handle user input to change the snake's direction

• Update the snake's position and check for collisions with walls or itself

• Add food to the boa...read more

Singleton pattern restricts the instantiation of a class to a single instance and provides a global point of access to it.

• Create a private constructor to restrict instantiation of the class

• Create a private static instance of the class

• Create a public ...read more

MVVM is a design pattern that separates UI logic from business logic.

• Model represents the data and business logic

• View displays the UI and user interactions

• ViewModel acts as a mediator between Model and View

• ViewModel exposes data and commands to the V...read more

A cab booking system designed using OOP principles

• Create classes for Cab, Customer, Driver, and Booking

• Use inheritance and polymorphism to handle different types of cabs and bookings

• Implement methods for booking a cab, assigning a driver, and calcula...read more

Implement a Least Recently Used (LRU) cache data structure that supports get and put operations efficiently.

• Design a data structure that maintains a cache with a specified capacity.

• Implement get(key) function to return value associated with key or -1...read more

Design and implement a Least Frequently Used (LFU) Cache with put and get functionalities, handling capacity and frequency of use.

• Implement a LFU cache with put and get functions

• Handle capacity and frequency of use for eviction

• Return the value of key...read more

Microservices architecture involves designing applications as a collection of loosely coupled services, each focused on a specific business function.

• Decomposition: Breaks down applications into smaller, manageable services (e.g., user service, order ...read more

Use the Strategy Pattern for complex designs to encapsulate algorithms and make them interchangeable.

• Encapsulates algorithms: Allows you to define a family of algorithms, encapsulate each one, and make them interchangeable.

• Promotes flexibility: Clien...read more

MVC is a design pattern for structuring applications, while Factory is a creational pattern for object creation.

• MVC stands for Model-View-Controller, which separates application logic into three interconnected components.

• Factory pattern is used to cr...read more

Architectural patterns define the overall structure and organization of a system, while design patterns provide solutions to specific design problems within the system.

• Architectural patterns focus on high-level decisions about the system's structure,...read more

Repository Pattern is a design pattern that separates data access logic from business logic.

• It provides a way to access data from a data source without exposing the underlying database or data store.

• It helps in achieving separation of concerns and ma...read more

Repository pattern using EF core for data access layer

• Create an interface for the repository with generic CRUD methods

• Implement the repository interface with EF core for data access

• Use dependency injection to inject the repository into services

• Separa...read more

Design a classic Snake game based on Nokia phones.

• Use a 2D array to represent the game board.

• Implement logic for snake movement and growth.

• Include collision detection with walls and itself.

• Add food items for the snake to eat and grow.

• Display the game...read more

Design a lift system using OOPs concepts.

• Create a Lift class with methods like moveUp(), moveDown(), openDoor(), closeDoor()

• Create a Floor class with methods like requestLift()

• Use inheritance to create different types of lifts like passenger lift, ca...read more

Design a class that limits maximum 3 instances and repeats them from 4th call.

• Create a private static array to hold instances.

• Create a private static counter to keep track of instance count.

• Create a public static method to get instance of the class.

• I...read more

Factory Design pattern is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.

• Factory Design pattern is used to create objects without sp...read more

An API Gateway pattern acts as a single entry point for managing and routing requests to various microservices.

• Centralizes access to multiple microservices, simplifying client interactions.

• Handles cross-cutting concerns like authentication, logging, ...read more

The design pattern commonly used in Angular is the Observer pattern.

• The Observer pattern is used to establish a one-to-many dependency between objects.

• In Angular, Observables are used to implement the Observer pattern for handling asynchronous data s...read more

The mostly used design patterns in JavaScript are Module, Observer, Singleton, Factory, and Prototype.

• Module pattern helps to keep the code organized and maintainable.

• Observer pattern is used for event handling and notification.

• Singleton pattern rest...read more

Splitwise is a system for managing shared expenses among groups of people.

• 1. Allow users to create groups and add members to track shared expenses.

• 2. Implement features for adding expenses, specifying who paid and who owes.

• 3. Calculate balances for e...read more

SOLID principles are five design principles aimed at making software designs more understandable, flexible, and maintainable.

• S - Single Responsibility Principle: A class should have one reason to change. Example: A User class should only handle user ...read more

Static is a keyword used to declare a variable or method that belongs to the class. Singleton is a design pattern that restricts the instantiation of a class to one object.

• Static members are accessed using the class name, while Singleton objects are ...read more

The design process for building a chatbot involves defining user goals, choosing a platform, designing conversation flow, implementing natural language processing, and testing for accuracy.

• Define user goals and objectives for the chatbot

• Choose a plat...read more