UST Senior Software Developer Interview Questions and Answers

Python core concepts and basic coding challenges

Q1. I have given interview for forntend angular developer. Questions were related with basics of angular, javascript and javascript coding. then in second technical round advanced angular related questions wer...read more
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Round duration - 60 minutes
Round difficulty - Medium

This round had 1 question related to DSA and then the rest of the questions were from Java , OOPS and Spring Boot.

Q1. 
Middle of Linked List
Given the head node of a singly linked list, your task is to return a pointer to the middle node of the linked list.
If there are an odd number of elements, return the middle elemen...read more
Ans. 
Return the middle node of a singly linked list, considering odd and even number of elements.
• Traverse the linked list with two pointers, one moving twice as fast as the other

• When the fast pointer reaches the end, the slow pointer will be at the middle

• Return the node pointed by the slow pointer as the middle node
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Q2. How does ConcurrentHashMap work in Java?
Ans. 
ConcurrentHashMap in Java is a thread-safe version of HashMap, allowing multiple threads to access and modify the map concurrently.
• ConcurrentHashMap achieves thread-safety by dividing the map into segments, each guarded by a separate lock.

• It allows multiple threads to read and write to the map concurrently, without blocking each other.

• It provides better performance than synchronized HashMap for concurrent operations.

• Ex...read more
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Q3. What are the features of a lambda expression in Java 8?
Ans. 
Lambda expressions in Java 8 are used to provide a concise way to represent a single method interface.
• Lambda expressions are used to provide implementation of functional interfaces.

• They enable you to treat functionality as a method argument, or code as data.

• Syntax of lambda expressions is (argument) -> (body).

• Example: (int a, int b) -> a + b
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Q4. What is dependency injection?
Ans. 
Dependency injection is a design pattern where components are provided with their dependencies rather than creating them internally.
• Allows for easier testing by providing mock dependencies

• Promotes loose coupling between components

• Improves code reusability and maintainability

• Examples: Constructor injection, Setter injection, Interface injection
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Q5. What is the difference between the PUT and POST methods in API?
Ans. 
PUT is used to update or replace an existing resource, while POST is used to create a new resource.
• PUT is idempotent, meaning multiple identical requests will have the same effect as a single request

• POST is not idempotent, meaning multiple identical requests may have different effects

• PUT requests are used to update an existing resource with a new representation, while POST requests are used to create a new resource

• PUT ...read more
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Q6. Can you explain the SOLID principles in Object Oriented Design?
Ans. 
SOLID principles are a set of five design principles in object-oriented programming to make software designs more understandable, flexible, and maintainable.
• S - Single Responsibility Principle: A class should have only one reason to change.

• O - Open/Closed Principle: Software entities should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Objects of a superclass should be replaceable...read more
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Q7. What do you mean by virtual functions in C++?
Ans. 
Virtual functions in C++ allow a function to be overridden in a derived class, enabling polymorphic behavior.
• Virtual functions are declared in a base class with the 'virtual' keyword.

• They are meant to be overridden in derived classes to provide specific implementations.

• When a virtual function is called through a base class pointer or reference, the actual function to be executed is determined at runtime based on the ob...read more
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Round duration - 60 minutes
Round difficulty - Medium

This round started with some questions from Spring Boot and Hibernate and then the interviewer moved on to some more questions from MVC and Microservices.

Q1. What are the basic annotations that Spring Boot offers?
Ans. 
Spring Boot offers basic annotations like @Controller, @RestController, @Service, @Repository, @Component.
• @Controller - Used to mark a class as a Spring MVC controller.

• @RestController - Combination of @Controller and @ResponseBody, used to create RESTful web services.

• @Service - Used to mark a class as a service component in Spring.

• @Repository - Used to mark a class as a data access component in Spring.

• @Component - Gene...read more
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Q2. Can you explain the @RestController annotation in Spring Boot?
Ans. 
The @RestController annotation in Spring Boot is used to define a class as a RESTful controller.
• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need to annotate every method with @ResponseBody

• Returns data directly in the response body as JSON or XML
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Q3. What is Hibernate caching?
Ans. 
Hibernate caching is a mechanism used to improve the performance of applications by reducing the number of database queries.
• Hibernate caching stores frequently accessed data in memory to reduce the need for repeated database queries.

• There are different levels of caching in Hibernate, such as first-level cache and second-level cache.

• First-level cache is associated with the Session object and is enabled by default.

• Second...read more
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Q4. Can you explain the N+1 SELECT problem in Hibernate?
Ans. 
N+1 SELECT problem in Hibernate occurs when a query results in N+1 database queries being executed instead of just one.
• Occurs when a query fetches a collection of entities and then for each entity, another query is executed to fetch related entities individually

• Can be resolved by using fetch joins or batch fetching to fetch all related entities in a single query

• Example: Fetching a list of orders and then for each order...read more
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Q5. What are the concurrency strategies available in Hibernate?
Ans. 
Hibernate provides several concurrency strategies like optimistic locking, pessimistic locking, and versioning.
• Optimistic locking: Allows multiple transactions to read a row simultaneously, but only one can update it at a time.

• Pessimistic locking: Locks the row for exclusive use by one transaction, preventing other transactions from accessing it.

• Versioning: Uses a version number to track changes to an entity, allowing ...read more
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Q6. Can you explain in brief the role of different MVC components?
Ans. 
MVC components include Model (data), View (UI), and Controller (logic) for organizing code in a software application.
• Model: Represents data and business logic, interacts with the database. Example: User model storing user information.

• View: Represents the UI, displays data to the user. Example: HTML/CSS templates for displaying user profile.

• Controller: Handles user input, updates the model, and selects the view to displ...read more
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Q7. How is routing carried out in MVC?
Ans. 
Routing in MVC is the process of mapping URLs to controller actions.
• Routing is defined in the RouteConfig.cs file in ASP.NET MVC applications.

• Routes are defined using the MapRoute method, which specifies the URL pattern and the controller and action to handle the request.

• Routes are matched in the order they are defined, with the first match being used to handle the request.

• Route parameters can be defined in the URL pat...read more
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Q8. Explain how independent microservices communicate with each other.
Ans. 
Independent microservices communicate through APIs, messaging queues, or event-driven architecture.
• Use RESTful APIs for synchronous communication between microservices

• Implement messaging queues like RabbitMQ or Kafka for asynchronous communication

• Leverage event-driven architecture with tools like Apache Kafka or AWS SNS/SQS

• Consider gRPC for high-performance communication between microservices
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Q9. Can you explain OAuth?
Ans. 
OAuth is an open standard for access delegation, commonly used for enabling secure authorization between applications.
• OAuth allows a user to grant a third-party application access to their resources without sharing their credentials.

• It uses tokens (access token, refresh token) to provide secure access to resources.

• OAuth is commonly used in scenarios where a user wants to grant access to their social media accounts or c...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a Technical Cum HR round where I was first asked some basic Java related concepts and then we discussed about my expectations from the company , learnings and growth in the forthcomig years. I would suggest be honest and try to communicate your thoughts properly in these type of rounds to maximise your chances of getting selected.

Q1. Why are you looking for a job change?
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