UL Solutions Senior Software Engineer Interview Questions and Answers

It was a test to create a login page and connect to database

Q1. What is difference between interface and abstract class
Ans. 
Interface is a contract with no implementation, while abstract class can have some implementation.
• Interface cannot have any implementation, only method signatures

• Abstract class can have both abstract methods and concrete methods

• A class can implement multiple interfaces but can only inherit from one abstract class

• Interfaces are used to achieve multiple inheritance in Java
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Q2. What are main concepts of oops
Ans. 
Main concepts of OOP include 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 and showing only the nec
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Q1. Interview was for .NET Full Stack Developer 1. What is the difference between .Use and .Run in Configure method in startup class in .NET core applications. 2. What are SOLID principles? 3. What are AWS ...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round started slow with some basic fundamental questions around OOPS and then paced up higher to some more advanced questions Java and Multithreading in Java in general.

Q1. 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 more maintainable, flexible, and scalable.
• Single Responsibility Principle (SRP) - A class should have only one reason to change.

• Open/Closed Principle (OCP) - Software entities should be open for extension but closed for modification.

• Liskov Substitution Principle (LSP) - Objects of a superclass should be replaceable with...read more
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Q2. What is abstraction in Object-Oriented Programming?
Ans. 
Abstraction in OOP is the concept of hiding complex implementation details and showing only the necessary features to the outside world.
• Abstraction allows us to focus on what an object does instead of how it does it

• It helps in reducing complexity and improving maintainability of code

• Example: In a car, we don't need to know the internal workings of the engine to drive it
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Q3. How is an abstract class different from an interface?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, fields, and methods with implementation.

• Interface can only have abstract methods and constants.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Example: Abstract class - Animal with abstract method 'eat', Interface - Flyable with metho
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Q4. What is a classloader in Java?
Ans. 
A classloader in Java is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine.
• Classloaders are responsible for loading classes at runtime based on the fully qualified name of the class.

• There are different types of classloaders in Java such as Bootstrap Classloader, Extension Classloader, and Application Classloader.

• Classloaders follow a delegation model where a classl...read more
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Q5. Why is Java considered platform independent, while the Java Virtual Machine (JVM) is platform dependent?
Ans. 
Java is platform independent because it compiles code into bytecode that can run on any system with a JVM, which is platform dependent.
• Java code is compiled into bytecode, which is platform independent

• The JVM interprets the bytecode and translates it into machine code specific to the underlying platform

• This allows Java programs to run on any system with a JVM installed, making Java platform independent
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Q6. Can you tell us something about the JIT compiler?
Ans. 
JIT compiler stands for Just-In-Time compiler, which dynamically compiles and optimizes code during runtime.
• JIT compiler is used to improve the performance of applications by compiling code at runtime instead of ahead of time.

• It converts bytecode into native machine code on-the-fly, allowing for faster execution.

• Examples of JIT compilers include HotSpot for Java and V8 for JavaScript.
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Q7. Can you explain what a thread pool is?
Ans. 
A thread pool is a collection of worker threads that are used to execute tasks concurrently.
• Thread pools help manage and reuse threads to improve performance and reduce overhead.

• They limit the number of concurrent threads to prevent resource exhaustion.

• Tasks are submitted to the pool and executed by available threads.

• Example: Java's Executor framework provides implementations of thread pools like ThreadPoolExecutor.
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Q8. What is the difference between the interrupted() and isInterrupted() methods in Java?
Ans. 
interrupted() checks if the current thread has been interrupted, while isInterrupted() checks if a thread has been interrupted.
• interrupted() is a static method in the Thread class, while isInterrupted() is an instance method.

• interrupted() clears the interrupted status of the current thread, while isInterrupted() does not.

• Example: Thread.currentThread().interrupt(); System.out.println(Thread.interrupted()); // prints tr...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This round primarily focused on some major concepts in Spring Boot and Hibernate and had questions revolving around
that with some more questions from Microserviices and Java Design Patterns.

Q1. How many bean scopes are supported by Spring?
Ans. 
Spring supports five bean scopes: singleton, prototype, request, session, and application.
• Singleton scope creates a single instance per Spring IoC container.

• Prototype scope creates a new instance every time the bean is requested.

• Request scope creates a new instance for each HTTP request.

• Session scope creates a single instance per HTTP session.

• Application scope creates a single instance per ServletContext.
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Q2. What do you understand by autowiring in Spring Boot, and can you name the different modes of autowiring?
Ans. 
Autowiring in Spring Boot is a way to automatically inject dependencies into a Spring bean.
• Autowiring is a feature in Spring that allows the container to automatically inject the dependencies of a bean.

• There are different modes of autowiring in Spring: 'byName', 'byType', 'constructor', 'autodetect', and 'no'.

• For example, in 'byName' autowiring, Spring looks for a bean with the same name as the property being autowired
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Q3. 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 each method with @ResponseBody
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Q4. What does the @SpringBootApplication annotation do internally?
Ans. 
The @SpringBootApplication annotation is used to mark the main class of a Spring Boot application.
• It is a combination of @Configuration, @EnableAutoConfiguration, and @ComponentScan annotations.

• It tells Spring Boot to start adding beans based on classpath settings, other beans, and various property settings.

• It also implicitly provides a base package for component scanning.

• Example: @SpringBootApplication

• Example: @Spring...read more
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Q5. Can you explain Spring Actuator and its advantages?
Ans. 
Spring Actuator is a set of production-ready features to help monitor and manage your application.
• Provides insights into application's health, metrics, and other useful information

• Enables monitoring and managing of application through HTTP endpoints

• Can be used to check application's health, view metrics, and even perform custom actions

• Helps in identifying and troubleshooting issues in production environment
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Q6. What are the concurrency strategies available in Hibernate?
Ans. 
Hibernate provides various 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. Uses versioning or timestamp to check for conflicts.

• Pessimistic locking: Locks the row for exclusive use by one transaction, preventing other transactions from accessing it until the lock is rel...read more
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Q7. Can you explain the working of Microservice Architecture?
Ans. 
Microservice architecture is an architectural style that structures an application as a collection of loosely coupled services.
• Microservices are small, independent services that work together to form a complete application.

• Each microservice is responsible for a specific business function and can be developed, deployed, and scaled independently.

• Communication between microservices is typically done through APIs.

• Microserv...read more
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Q8. What issues are generally addressed by Spring Cloud?
Ans. 
Spring Cloud addresses issues related to building and deploying cloud-native applications.
• Service discovery and registration

• Load balancing

• Circuit breakers

• Distributed configuration management

• Routing and gateway

• Monitoring and tracing
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Q9. Can you explain the Singleton design pattern?
Ans. 
Singleton design pattern ensures a class has only one instance and provides a global point of access to it.
• Ensures a class has only one instance by providing a global access point to it

• Uses a private constructor to restrict instantiation of the class

• Provides a static method to access the single instance
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Round duration - 30 Minutes
Round difficulty - Easy

This is a cultural fitment testing round. HR was very frank and asked standard questions. Then we discussed about my
role.

Q1. Why should we hire you?
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Q2. Why are you looking for a job change?
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Round duration - 90 Minutes
Round difficulty - Medium

Q1. 
Duplicate Integer in Array
Given an array ARR of size N, containing each number between 1 and N-1 at least once, identify the single integer that appears twice.
Input:
The first line contains an integer...read more
Ans. 
Identify the duplicate integer in an array containing numbers between 1 and N-1.
• Iterate through the array and keep track of the frequency of each element using a hashmap.

• Return the element with a frequency greater than 1 as the duplicate integer.

• Ensure the constraints are met and a duplicate number is guaranteed to be present.
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Round duration - 45 Minutes
Round difficulty - Medium

They wants to Check your Problem solving techniques with best case and how you approach a problem and the way you solve
they wants to solve in more than one way 
also they ask basic Questions Related to your frame Work you are working

Q1. 
Anagram Pairs Verification
In this task, you need to verify if two provided strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form t...read more
Ans. 
Verify if two strings are anagrams of each other by rearranging their letters.
• Create character frequency maps for both strings.

• Compare the frequency of characters in both maps to check if they are anagrams.

• Return 'True' if the frequencies match, else return 'False'.
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Round duration - 20 Minutes
Round difficulty - Easy

General About yourSelf and How was your previous round and CTC discussion

Q1. Can you discuss the CTC (Cost to Company) offered in this position?
Ans. 
The CTC offered for this position is competitive and includes salary, benefits, and bonuses.
• CTC includes salary, benefits, bonuses, and other perks

• Negotiation may be possible based on experience and skills

• CTC details are typically discussed during the final stages of the interview process
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Coding test based on Array , Map ,set and linked list

Q1. Kotlin, core android and project related questions
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Q1. Client round - kotlin , di , coding and core android questions
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Q1. Salary discussions only
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Q1. Basic java and angular questions
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Basic technical question on finding duplicate alphabets in a string

Q1. What is your plan 5 years down the line, how to resolve conflict in the team
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Q1. Questions related to background. Resume based.
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Q1. Area of interest - Backend, frontend, databases, cloud etc
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Q1. Areas of interest - Backend, frontend, databases, cloud, etc
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Q1. Behavioral interview with the Parter/Principal
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