Mercuryminds Technologies Reactjs Developer Interview Questions and Answers for Experienced

Q1. Dependency injection
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Q2. What are oops concepts
Ans. 
Object-oriented programming concepts that focus on data encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: bundling data and methods that operate on the data into a single unit (class)

• Inheritance: ability of a class to inherit properties and behavior from another class

• Polymorphism: ability to present the same interface for different data types

• Abstraction: hiding the complex implementation details
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Q1. Why do you want to switch
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I want to switch to explore new technologies and challenges in a different industry.
• Interested in learning new skills and technologies

• Seeking new challenges and opportunities for growth

• Want to explore different industry perspectives
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Q2. Salry expectations
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Q1. Question on oop concepts
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Q2. Coding questions
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Q1. Intro your self
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Q2. Please tell me what is oops?
Ans. 
OOPs stands for Object-Oriented Programming. It is a programming paradigm based on the concept of objects, which can contain data and code.
• OOPs focuses on creating objects that interact with each other to solve a problem

• It involves concepts like classes, objects, inheritance, encapsulation, and polymorphism

• Example: In a banking system, a 'BankAccount' class can have objects like 'SavingsAccount' and 'CheckingAccount'
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Q3. What is stream api?
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Q4. How hasmap internally work
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HashMap internally uses an array of linked lists to store key-value pairs, with keys being hashed to determine the index in the array.
• HashMap uses hashing to determine the index of the key in the array.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• HashMap allows null keys and values.

• HashMap is not synchronized, use ConcurrentHashMap for thread-safe operations.
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Q5. How stream is differ between stream api
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Stream API is a feature in Java that allows processing collections of objects in a functional style.
• Stream API is used to process collections of objects in a functional style.

• Stream API provides a set of methods to perform operations on the elements of a collection.

• Stream API supports operations like filter, map, reduce, and collect.

• Stream API is part of the java.util.stream package in Java.
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Q1. Tell me about any of the design patterns you are familiar with
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I am familiar with design patterns such as Singleton, Factory, Observer, and MVC.
• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying the exact class of object that will be created.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and up...read more
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Q2. Design a system for a company in hospitality
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Design a system for a company in hospitality
• Implement a centralized reservation system for booking rooms, tables, and other services

• Incorporate a customer feedback system to gather reviews and ratings for continuous improvement

• Include a staff scheduling and management module to efficiently allocate resources

• Integrate a payment gateway for secure transactions and invoicing

• Utilize data analytics to track customer prefere
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Q3. How and where did you implement threads
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Implemented threads in a multi-threaded application to improve performance and concurrency.
• Implemented threads in a multi-threaded application to handle multiple tasks concurrently

• Used threads to improve performance by parallelizing tasks

• Implemented threads in a web server to handle multiple client requests simultaneously
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Q4. DSA questions I don't remember but they were from leetcode and gfg. Focus on Medium level more than easy or hard. Also heap
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Q1. Java 8 features, functional Interfaces and predefined functional interfaces, Streams
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Q2. Collections, Aggregations, solid principles in Java
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Q3. Design patterns, singleton and factory explain in detail
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Design patterns are reusable solutions to common problems in software design. Singleton ensures a class has only one instance, while factory creates objects without specifying the exact class.
• Design patterns are best practices for solving common software design problems.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying ...read more
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Q4. Spring functions, Spring Runners, Spring Exception handling
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Q5. Springboot annotations except common(any 5)
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Q6. Write spring boot program to accept json as request. write the logic and explain
Ans. 
Create a Spring Boot program to accept JSON requests and process the data.
• Create a Spring Boot application with a REST controller to handle incoming JSON requests.

• Use @PostMapping annotation to map the endpoint for accepting JSON requests.

• Use @RequestBody annotation to bind the incoming JSON data to a Java object.

• Process the JSON data as needed in the controller method.

• Return a response as JSON if required.
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Q1. What are the hooks you used?
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I have used useState, useEffect, useContext, and useRef hooks in my projects.
• useState - for managing state in functional components

• useEffect - for handling side effects in functional components

• useContext - for accessing context in functional components

• useRef - for accessing DOM elements or storing mutable values
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Q2. Complete details of last project worked
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Q1. Question were asked on basics of Java and SQL. Eg:- OOPS concepts, Collections
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Q1. Questions were asked specific topics on Java and SQL again. This time it was moderate. Eg:- Exception Handling, Springboot, Subquery, Joins etc
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Q1. This round was normal and HR was explaining the company policies and discussed the package.
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Print pattern and recursive program

Q1. Technical question ask link c#,Api,mvc, Angular ,core.net
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Q1. Introduction and educational , work experience
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