Neustar Java Developer Interview Questions and Answers

Q1. What is kafka? how to implement it
Ans. 
Kafka is a distributed streaming platform used for building real-time data pipelines and streaming applications.
• Kafka is designed to handle high-throughput, fault-tolerant, and scalable real-time data streams.

• It uses topics to categorize data streams, producers publish messages to topics, and consumers subscribe to topics to process messages.

• Kafka can be implemented using Kafka APIs in Java, Scala, or other programming...read more
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Q2. What is Oauth and what is use of it?
Ans. 
OAuth is an open standard for access delegation, commonly used as a way for Internet users to grant websites or applications access to their information on other websites but without giving them the passwords.
• OAuth allows users to grant access to their information on one site to another site without sharing their credentials.

• It is commonly used for authentication and authorization in APIs.

• OAuth uses tokens to access re...read more
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Q1. Data structures Core java Spring boot Hibernate
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2 DSA question was asked

40 questions in 20 minutes

Q1. Stones games 2 leetcode
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Q2. Permutations of array
Ans. 
Generate all possible permutations of an array of strings
• Use recursion to generate permutations

• Swap elements to create different permutations

• Base case: when array size is 1, return array as permutation
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Q1. Project discussion
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Reasoning and aptitude questions are given

Q1. Tell all concepts of Overloading
Ans. 
Overloading is a concept in programming where multiple functions can have the same name but different parameters.
• Functions with the same name but different parameters can be defined in a class

• Overloading allows for flexibility in function usage

• Example: void print(int num) and void print(string text) are overloaded functions
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Q2. Tell me about a live example of inheritance
Ans. 
Inheritance in software development allows a class to inherit properties and behaviors from another class.
• Inheritance allows a subclass to reuse code from a superclass

• Subclass can also add new functionalities or override existing ones

• Example: Animal class can be a superclass with properties like name and age, while Dog class can inherit from Animal and add a method bark()
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Q1. Tell about the your self
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Q1. SDLC process and how it is implemented in project
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Q2. About projects, it's Objective, the role I have worked, output
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Q3. Data structure, DBMS concepts
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Q1. Lookup vs graphlookup in mongodb
Ans. 
Lookup is used to perform a left outer join in MongoDB, while graphlookup is used to perform recursive graph traversal.
• Lookup is used to perform a left outer join between two collections in MongoDB.

• Graphlookup is used to perform recursive graph traversal in a collection that contains graph data.

• Lookup can only perform a single level join, while graphlookup can perform multiple levels of traversal.

• Lookup is faster than
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Q2. Count frequency of each character in string
Ans. 
Use a hashmap to count the frequency of each character in a string.
• Create a hashmap to store characters as keys and their frequencies as values.

• Iterate through the string and update the hashmap accordingly.

• Return the hashmap with character frequencies.
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Q1. Create a rest api all the way from controller to repository using NOTEPAD
Ans. 
Creating a REST API from controller to repository using NOTEPAD
• Create a controller class with mapping annotations for REST endpoints

• Implement service layer to handle business logic and interact with repository

• Define repository interface with methods for data access operations

• Use Spring Boot for easy setup and configuration

• Test API endpoints using tools like Postman
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Q2. Couldnt write custom mongodb query at repository layer in notepad which rejected my candidature.
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60mintues DSA level coding exam