Indium Software Java Developer Interview: Rounds, Questions and Preparation

What the job involves

Java Developers in Indian IT services build and maintain backend components of web and enterprise applications, often working on client projects across domains like banking, retail, or healthcare. A fresher typically writes code for assigned modules, fixes bugs, writes unit tests, and coordinates with senior developers and testers in an agile team. The role demands strong Core Java and database basics, plus the ability to learn frameworks like Spring and Hibernate on the job.

Role and Technical Knowledge

1. 1

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

   Explain that abstract classes can have state and constructors while interfaces define a contract; use interfaces for multiple inheritance of type and abstract classes for shared code. Give a small example from a service layer.

2. 2

   How does HashMap work internally in Java?

   Cover hashing, buckets, equals and hashCode contract, collision handling with linked lists or trees, and resizing. Mention that poor hashCode can degrade performance.

3. 3

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

   Checked exceptions must be declared or handled at compile time (e.g., IOException); unchecked are runtime (e.g., NullPointerException). Explain when to create custom exceptions.

4. 4

   Explain the Spring Boot starter dependencies and how dependency injection works.

   Describe how starters simplify build configuration and how Spring container manages beans via constructor or field injection. Mention @Autowired and component scanning.

Practical Scenarios

1. 5

   You are asked to write a Java method that reads a large CSV file and inserts records into a database. How would you approach it?

   Mention using BufferedReader or streaming, batch inserts with JDBC, transaction management, and handling malformed rows. Show awareness of memory and performance.

2. 6

   A REST API you built returns a 500 error only in production but works locally. How do you debug it?

   Talk about checking logs, environment differences, configuration, database connectivity, and using tools like Postman. Emphasize systematic isolation of variables.

3. 7

   How would you design a simple URL shortener service using Java and a database?

   Outline generating a unique short key, storing mapping in a table, handling collisions, and redirect logic. Mention caching for read-heavy traffic.

4. 8

   You need to add a new feature to an existing module without breaking other functionality. What steps do you take?

   Discuss understanding the existing code, writing unit tests, using Git branches, code review, and incremental integration. Show respect for legacy code.

Behavioural and HR Questions

1. 9

   Tell me about a time you worked in a team to complete a college project. What was your role?

   Use STAR format: situation, task, action, result. Highlight collaboration, your specific contribution, and what you learned about teamwork.

2. 10

   Why do you want to join a services company like ours rather than a product company?

   Show awareness of diverse client projects, learning opportunities across domains, and structured training. Avoid saying product companies are better.

3. 11

   How do you handle tight deadlines or pressure during a project?

   Give a concrete example of prioritising tasks, communicating early, and staying calm. Mention breaking work into smaller parts and seeking help when needed.

4. 12

   Are you willing to relocate or work on different technologies as project demands?

   Answer honestly but positively. Express flexibility and eagerness to learn, which is critical for IT services roles where project allocation varies.

Coding and Problem Solving

1. 13

   Write a Java program to reverse a string without using StringBuilder or StringBuffer.

   Use a char array and swap from both ends, or iterate backwards. Explain time and space complexity and handle null or empty input.

2. 14

   How would you find the first non-repeating character in a string using Java collections?

   Use LinkedHashMap to preserve insertion order and count frequencies, then iterate to find the first with count 1. Discuss alternative two-pass array approach.

3. 15

   Given a list of integers, write a Java 8 stream to filter even numbers and square them.

   Show stream(), filter(), map(), and collect(). Mention lambda expressions and that streams do not modify the original list.

4. 16

   Write a SQL query to find the second highest salary from an Employee table.

   Use a subquery with MAX and less than, or LIMIT with OFFSET, or DENSE_RANK. Explain null handling and why the subquery approach is portable.