Java | Project Interview | Epam Systems

Hi, recently had a project interview at Epam Systems, so here i am going to list all the questions i was asked during the interview.

Core

• Composition vs Inheritance?
• Exceptions in Java, try-catch, try-with resources
• Describe Java Memory Model, different parts of it?
• What is Garbage Collector? why we need it?
• Describe generational garbage collection, parts of heap that are devided into?
• Minor & Majar & Full garbage collection?
• What we store in Heap?
• Where java stores everything that is started with static? will they be alive all the time?
• ArrayList vs LinkedList?
• HashSet, HashMap inner workings? What is Red-Black tree?
• What is DAG? (asked because i said i now something about graph)

Test

• What types of tests do you know? Testing Pyramid

Spring & SpringBoot

• We have interface A and implementations of this interface: B, C concrete classes, what happens when we use DI with interface? How to solve this problem?
• How to get all instances of the same class from ApplicationContext?
• Scopes? Singleton vs Prototype?
• Is Singleton Thread safe?
• Spring vs SpringBoot?
• What is starters?
• What is Actuator?

Databases

• What kind of databases you know?
• What is Normalization? Normal Forms?
• What kind of relationships you know?
• Types of keys in RDBMS?
• NoSQL database types?

Git

• What is cherry-pick?

CI/CD

• Describe your experience with CI/CD tools, what you did?

Agile

• What is retrospectives in SCRUM?

Distributed Systems

• Why you used RabbitMQ in your project?
• What is Eureka? why we need it?
• CAP?
• Where Cassandra fits in CAP? Why is it the case?
• Tell about message guarentees: at-least-once, at-most-once, exactly-once?
• We have three micro services, deployed in Kubernetes. First microservice takes request from outside world, in second one we write to NoSQL database and in third we have auditing which writes logs to RDBMS. Our application is working slow, what are the steps you take to identify and fix this issue?

AWS Cloud

• What kind of AWS services you know?
• SNS vs SQS?
• We have messages in SQS and two consumers? Will both of the consumer recieves the message?
• What is the differences between defining our apis with AWS ApiGateWay and Spring?
• What is DynamoDB, DocumentDB?