Amstar Technologies Interview Questions and Answers

The aptitude test will be conducted online.

Q1. Can you tell me about yourself?
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Q2. What is the thread lifecycle in programming?
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Q3. What is the purpose of collections in Java?
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Q4. What are the key concepts of Object-Oriented Programming (OOP)?
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Q5. What are some real-life examples that illustrate the concepts of Object-Oriented Programming (OOP)?
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Q6. Write a code for matrix multiplication?
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Q7. Could you provide details about your academic project?
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Q1. Basic questions
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Q1. What are your salary expectations?
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Q2. What has been your experience in each of the companies you have worked for?
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Q1. Can you tell me about yourself?
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Q2. Could you briefly describe the companies you have worked for?
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Q3. What technologies have you worked with, and what was your role in each?
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Q4. What are some use case studies related to the technologies you have worked with?
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Q1. API Gateway implementation
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API Gateway implementation is a centralized service that routes, manages, and secures API calls.
• API Gateway acts as a single entry point for all API calls

• It can handle authentication, rate limiting, caching, and request/response transformations

• Examples include AWS API Gateway, Apigee, Kong
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Q2. Circuit breaker implementation
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Circuit breaker is a design pattern used to prevent system overload by temporarily stopping requests to a failing service.
• Circuit breaker monitors requests to a service and opens when the service fails repeatedly.

• It helps prevent cascading failures and allows the system to gracefully degrade.

• Once the circuit breaker is open, it can periodically check if the service has recovered before allowing requests again.
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Q3. What is deadlock? How to avoid it?
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Deadlock is a situation in which two or more processes are unable to proceed because each is waiting for the other to release a resource.
• Avoid circular wait by ensuring processes request resources in the same order.

• Prevent hold and wait by requiring processes to request all needed resources at once.

• Implement a timeout mechanism to break potential deadlocks.

• Use resource allocation graphs to detect and prevent deadlocks.

• ...read more
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Q4. Explain equals() method
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The equals() method is used to compare the contents of two objects for equality.
• The equals() method is a method of the Object class in Java.

• It is used to compare the contents of two objects for equality.

• The default implementation of equals() in the Object class compares memory addresses, so it is often overridden in custom classes to compare content.

• Example: String class overrides equals() method to compare the content
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Q5. How mongodb was integrated in your application?
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MongoDB was integrated in the application by using the official Java driver and configuring connection settings.
• Used the official MongoDB Java driver to interact with the database

• Configured connection settings such as host, port, database name, and authentication credentials

• Implemented CRUD operations using MongoDB Java driver methods

• Utilized MongoDB aggregation framework for complex queries
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Q6. What is hibernate?
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Hibernate is an open-source Java framework that simplifies the development of database interactions in Java applications.
• Hibernate is an Object-Relational Mapping (ORM) tool that maps Java objects to database tables.

• It provides a way to perform database operations using Java objects instead of writing SQL queries.

• Hibernate handles the mapping of Java classes to database tables and vice versa, as well as the generation ...read more
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Q7. Runnable vs Callable interface
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Runnable is a functional interface with a single run() method, while Callable is a functional interface with a single call() method.
• Runnable is used for tasks that do not return a result, while Callable is used for tasks that return a result.

• Callable can throw checked exceptions, while Runnable cannot.

• Callable returns a Future object, which can be used to retrieve the result of the computation.

• Example: Runnable - execu...read more
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Q8. Which type of data is returned by Callable interface?
Ans. 
The Callable interface in Java returns a Future object.
• Callable interface returns a Future object which represents the result of a computation that may not be available yet.

• The Future object can be used to retrieve the result of the computation, check if it is done, or cancel the computation.

• Example: Callable<Integer> task = () -> { return 42; }
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Q9. HashMap internal working
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Q10. Concurrent HashMap internal working
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Q11. How to monitor health of your application?
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Monitor application health using metrics, logs, alerts, and performance monitoring tools.
• Use monitoring tools like Prometheus, Grafana, or New Relic to track key metrics such as CPU usage, memory usage, response times, and error rates.

• Implement logging to record important events and errors in your application. Use tools like ELK stack (Elasticsearch, Logstash, Kibana) for log analysis.

• Set up alerts to notify you of any...read more
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Q12. How to call an API in a Microservice architecture?
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To call an API in a Microservice architecture, use HTTP requests or messaging protocols like gRPC.
• Use HTTP requests to communicate between microservices

• Implement RESTful APIs for easy integration

• Leverage messaging protocols like gRPC for efficient communication

• Consider using service discovery mechanisms for dynamic API calls
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Q13. Explain Profiles
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Profiles in Java are configurations that define the capabilities of a Java platform.
• Profiles allow developers to target specific types of devices or applications.

• They help in reducing the size of the Java runtime environment by including only the necessary APIs.

• Examples include Java SE Embedded Profile for embedded devices and Java SE Compact Profile for resource-constrained environments.
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Q14. What is OpenFeign, and how is it used in microservices architecture?
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OpenFeign is a declarative web service client used to simplify the process of making HTTP requests in microservices architecture.
• OpenFeign allows developers to define RESTful web services as interfaces and automatically generate the necessary implementation code.

• It integrates seamlessly with Spring Cloud and other microservices frameworks to facilitate communication between services.

• OpenFeign supports features like loa...read more
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Q15. What is the implementation process for service registry and discovery?
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Service registry and discovery involves registering services and allowing clients to discover and connect to them.
• Implement a service registry where services can register themselves with metadata

• Use a service discovery mechanism for clients to find and connect to services

• Implement health checks to ensure services are available and healthy

• Use a load balancer to distribute traffic among multiple instances of a service
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Q16. What are Spring boot actuators?
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Spring Boot Actuators are built-in tools that provide insight into the running application.
• Actuators expose various endpoints to monitor and manage the application.

• They can be used to check health, metrics, environment details, and more.

• Examples include /actuator/health, /actuator/metrics, and /actuator/env.
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Q17. Synchronous vs Asynchronous communication
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Synchronous communication is blocking, while asynchronous communication is non-blocking.
• Synchronous communication waits for a response before continuing, while asynchronous communication does not wait.

• Examples of synchronous communication include traditional function calls, while examples of asynchronous communication include callbacks and promises.

• Synchronous communication can lead to performance issues if there are d...read more
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Q18. Explain Synchronized keyword
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Synchronized keyword is used in Java to control access to shared resources by multiple threads.
• Synchronized keyword can be applied to methods or code blocks to ensure only one thread can access the synchronized code at a time.

• It prevents race conditions and ensures thread safety by creating a lock on the object or class.

• Example: synchronized void myMethod() { // synchronized code block }
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Q19. What are the consequences of excessively using synchronized blocks and methods in Java?
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Excessive use of synchronized blocks and methods in Java can lead to performance issues and potential deadlocks.
• Decreased performance due to increased contention for locks

• Potential deadlocks if multiple threads are waiting for each other to release locks

• Increased complexity and difficulty in debugging and maintaining code

• Use synchronized sparingly and consider alternatives like ConcurrentHashMap or Lock interface
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Q20. How can you determine the number of threads needed for your application?
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The number of threads needed for an application can be determined based on factors like the type of tasks, hardware resources, and performance requirements.
• Consider the type of tasks your application needs to perform - CPU-bound tasks may benefit from more threads, while I/O-bound tasks may not.

• Take into account the hardware resources available - more threads may be beneficial on a multi-core processor compared to a si...read more
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Q21. Explain Executor framework
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Executor framework is a framework in Java that provides a way to manage and execute tasks asynchronously.
• Allows for managing thread execution in a more efficient way

• Provides a way to decouple task submission from task execution

• Supports various types of executors like ThreadPoolExecutor and ScheduledExecutorService

• Helps in handling tasks concurrently and asynchronously
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Q22. Explain BlockingQueue
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BlockingQueue is an interface in Java that represents a queue which supports operations that wait for the queue to become non-empty when retrieving an element and wait for space to become available in the queue when adding an element.
• BlockingQueue is part of the java.util.concurrent package.

• It is used for implementing producer-consumer scenarios where multiple threads are involved.

• Methods like put() and take() are used...read more
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Q1. Why did you leave your previous company?
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Seeking new challenges and opportunities for growth.
• Desire for career advancement

• Looking for new challenges

• Seeking better work-life balance

• Company restructuring or downsizing

• Relocation to a new area
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Q2. Other basic questions asked regarding the relevant skills and technologies I have worked with.
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Q1. Basic Javascript questions were asked like Hoisting, Event Loop, Closure.
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Q2. What are semantic tags? << HTML based question
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Q3. What is currying in js?
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Q4. What is the difference between Map and Filter?
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Q5. What is the difference between Map and ForEach?
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Q6. What is the difference between Authentication and Authorization?
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Q7. What is the difference between Local storage and Session storage?
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Q1. This was the Final round, it lasted for around 30 mins and the interviewer gave me a coding question to build a Countdown Timer app.
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Q1. What are the different sizes available for a virtual warehouse in Snowflake, and which sizes are currently being utilized in your current project?
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Q2. What are stored procedures in Snowflake, and how did you utilize them?
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Q1. How did you verify the data after transferring it from one database to another?
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Q2. What are the different types of duplicate checks that can be performed using SQL queries?
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Q1. Are you open to relocating to Hyderabad?
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Q2. What information do you have about ValueLabs?
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Q1. What is the architecture of the Java Virtual Machine (JVM)?
Ans. 
The Java Virtual Machine (JVM) is an abstract computing machine that enables a computer to run Java programs.
• JVM is platform-independent and converts Java bytecode into machine code.

• It consists of class loader, runtime data areas, execution engine, and native method interface.

• JVM memory is divided into method area, heap, stack, and PC register.

• Examples of JVM implementations include Oracle HotSpot, OpenJ9, and GraalVM.
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Q2. What is the default connection pooling in Spring Boot, and how can it be customized?
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The default connection pooling in Spring Boot is HikariCP, which can be customized through properties in the application.properties file.
• HikariCP is the default connection pooling library in Spring Boot, known for its high performance and low overhead.

• To customize the connection pooling, you can modify properties like 'spring.datasource.hikari.*' in the application.properties file.

• For example, you can set maximum pool ...read more
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Q3. What are the best practices for optimizing a Spring Boot application?
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Best practices for optimizing a Spring Boot application
• Use Spring Boot Actuator to monitor and manage application performance

• Implement caching mechanisms like Spring Cache to reduce database calls

• Optimize database queries and indexes for better performance

• Use asynchronous processing with Spring's @Async annotation for non-blocking operations

• Profile and analyze application performance using tools like VisualVM or JProfi
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Q4. What is a heap dump, and how can it be used to identify memory leaks?
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A heap dump is a snapshot of the memory usage of a Java application at a specific point in time.
• Heap dumps can be generated using tools like jmap or VisualVM.

• They provide detailed information about objects in memory, their sizes, and references.

• Analyzing a heap dump can help identify memory leaks by pinpointing objects that are consuming excessive memory.

• Common signs of memory leaks in a heap dump include a large numbe...read more
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Q5. How can you diagonally iterate through and print the elements of a 2D array?program
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Diagonally iterate through and print elements of a 2D array of strings.
• Use nested loops to iterate through rows and columns of the 2D array.

• Calculate the diagonal elements by incrementing row and column indices together.

• Print the elements as you iterate through the diagonal of the array.
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Q1. Generic Regulatory related
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Q2. Medical devices class, medical regulatory and medical devices standards
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Q1. Verification process
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Q2. Regulatory affairs, Risk management
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An aptitude test is a standardized assessment that measures a person's potential and skills in a particular field or role. It's often used by employers during the recruitment process.

An "after interview assessment" refers to a test or evaluation that a company administers to a candidate after they have already had an initial interview, allowing the employer to further assess their skills, abilities, and suitability for the role beyond just the interview conversation; this could include things like technical skills tests, personality assessments, reference checks, or even further in-depth interviews with other team members depending on the role and company practices.

A group discussion (GD) in an interview is a selection process where a group of candidates are put together to discuss a given topic, allowing the interviewer to assess their communication skills, critical thinking, leadership abilities, and teamwork capabilities by observing how they interact and contribute to the conversation.

Q1. "Describe a time you had to address a performance issue with a high-performing employee."
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Q2. "Tell me about a time you successfully coached a team member through a challenging situation
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Q3. What are your salary expectations for this position?"'
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When asked "What are your salary expectations for this position?", the best answer is to provide a salary range based on your research of similar roles in the industry, considering your experience and qualifications, while stating that you are open to discussing further based on the specifics of the position and company benefits package; essentially, saying "Based on my research and experience, I'm looking for a salary...read more
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Q4. "Can you share an example of a time you demonstrated initiative in a previous role?"
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In my previous role as a [your job title], I noticed that our team was struggling with [specific problem or inefficiency]. To address this, I took the initiative to [action taken, like researching solutions, proposing a new process, or leading a project], which resulted in [positive outcome, like improved efficiency, increased sales, or better customer satisfaction].".
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Q5. "What are your career goals in the next 5 years, and how does this position align with them?"
Ans. 
In five years, I see myself continuing to grow in my career and taking on more responsibility within the company by leveraging the expertise I've gained working in this industry for the past 5 years. I'm also looking to start a family in the next few years, so I'll be balancing work and home life.
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Q6. Why do you want to work for us or our company?
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Q7. What are your strengths and weaknesses?
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Q1. Pyspark architecture
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Q2. Optimisation in pyspark
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Q3. Null handling in spark
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Q4. Operators in airflow
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Q5. Sql coding for average rolling , lead lag
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Q6. Mysql to gcs ,how to move 10 tables at a time?
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Q7. Explode json data
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Q8. Error logs
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