Winfo Solutions Java Trainer Interview Questions and Answers

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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Q1. Data structures Core java Spring boot Hibernate
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Q1. Oops, Interfaces, Exception Handling, Collections, SQL, etc
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Q2. Coding Question - Find 2nd largest element in array with least time complexity
Ans. 
Find the 2nd largest element in an array with the least time complexity.
• Sort the array in descending order and return the element at index 1.

• Initialize two variables to keep track of the largest and second largest elements.

• Iterate through the array and update the variables accordingly.

• Return the second largest element.
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Q1. Coding Question - print * matrix
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Q2. HashMap, HashSet, Spring, Spring Framework, Microservices, etc
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Q1. Basic Details, CTC Info
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Q2. Tech Stack, Challenges Faced in career
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Q1. Java fundamentals
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Q2. Spring fundamentals
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Q1. Managerial round
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Q2. Scenario based questions
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Opps,java basics, question on array and string as an array

Q1. Machine round collection framework pattern design array mid term SIngleton design pattern
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Q1. More dmbs and sql questions salary
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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. Definition of oops
Ans. 
Object-oriented programming paradigm that focuses on objects and classes for code organization and reusability.
• Encapsulation: bundling data and methods that operate on the data into a single unit (object)

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

• Polymorphism: ability to present the same interface for different data types
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Q1. Tell me about your hobby and tell me about past birthday
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