Yotta Data Services Java Developer Interview: Rounds, Questions and Preparation

What the job involves

Java Developers in Indian IT services build, test, and maintain enterprise applications for clients across domains like BFSI, telecom, and government. Day to day work includes writing clean Java code, fixing bugs, integrating with databases and APIs, and participating in Agile ceremonies. Freshers usually start on maintenance or enhancement projects and gradually move to core development.

Role and Technical Knowledge

1. 1

   Explain the difference between JDK, JRE, and JVM.

   Define each clearly: JDK for development, JRE to run Java programs, JVM to execute bytecode. Mention that JVM is platform dependent but bytecode is platform independent.

2. 2

   What is the difference between an abstract class and an interface in Java? When would you use each?

   Cover that abstract classes can have constructors and state, interfaces define contracts. Use abstract class for shared code, interface for multiple inheritance of type. Mention Java 8 default methods.

3. 3

   How does HashMap work internally in Java?

   Explain hashing, buckets, equals and hashCode contract, and collision handling with linked list or tree. Mention that Java 8 converts long chains to red black trees.

4. 4

   What is the difference between checked and unchecked exceptions? Give an example of each.

   Checked exceptions must be handled or declared (e.g., IOException), unchecked are runtime (e.g., NullPointerException). Emphasize when to use custom exceptions in service layers.

Practical Scenarios

1. 5

   You need to fetch employee records from a database and expose them as a REST API. How would you design this using Spring Boot?

   Outline layers: controller, service, repository. Use Spring Data JPA for database access, return JSON, handle exceptions with @ControllerAdvice. Mention pagination for large data.

2. 6

   A production Java application is running out of memory. How would you debug and resolve it?

   Mention heap dump analysis, checking for memory leaks, using tools like jvisualvm or Eclipse MAT. Suggest increasing heap size only after finding root cause, and reviewing object retention.

3. 7

   How would you write a SQL query to find the second highest salary from an Employee table?

   Use a subquery with LIMIT and OFFSET or a correlated subquery. Explain that different databases have different syntax. Mention handling ties and nulls.

4. 8

   You are asked to add a new feature to an existing legacy Java codebase with no tests. What is your approach?

   Start by understanding the code, write characterization tests for current behavior, then refactor incrementally. Use version control and small commits. Communicate risks to the team.

Behavioural and Situational

1. 9

   Tell me about a time you faced a difficult bug in a college project. How did you resolve it?

   Use STAR method: describe the bug, your debugging steps, tools used, and the outcome. Highlight persistence and learning from the experience.

2. 10

   You are assigned a task with unclear requirements and a tight deadline. What do you do?

   Show that you ask clarifying questions early, break the task into smaller parts, and communicate progress. Mention prioritizing core functionality and seeking help when needed.

3. 11

   Describe a situation where you had to work in a team to complete a project. What was your role?

   Focus on collaboration, your specific contribution, and how you handled disagreements. Emphasize communication and meeting deadlines together.

4. 12

   How do you handle feedback or criticism from a senior developer?

   Show openness to learning, ask for specifics, and apply the feedback. Mention that you view it as a chance to improve code quality and grow.

HR and Company Fit

1. 13

   Why do you want to join the IT services sector, and what do you know about our company?

   Research the company's services, clients, and recent news. Connect your interest to their work in cloud, data centers, or digital transformation. Avoid generic answers.

2. 14

   Are you willing to relocate or work in different shifts as per project requirements?

   Be honest but flexible. Mention that you understand IT services often require shift work or relocation and you are open to it for learning and career growth.

3. 15

   Where do you see yourself in the next three years?

   Align your goals with the company: becoming a strong developer, learning new technologies, and taking more responsibility. Avoid saying you want to leave for higher studies or other companies.

4. 16

   What are your salary expectations for this role?

   For fresher roles, say you are open to the company's standard fresher package and more focused on learning. If pressed, give a range based on market research for Indian IT services.