Chargebee India Java Developer Interview: Rounds, Questions and Preparation

What the job involves

As a Java Developer at an Indian IT services company, you will write, test, and maintain server-side code, often as part of a larger product or client project. Day to day involves working with Java, Spring Boot, databases, and REST APIs, fixing bugs, and collaborating with senior developers and QA. Freshers usually start with well-defined modules and gradually take on more complex features.

Java and Programming Fundamentals

1. 1

   Explain the difference between an interface and an abstract class in Java, and when you would use each.

   Mention that interfaces support multiple inheritance and define contracts, while abstract classes can have state and partial implementation. Give a scenario like using an interface for a service API and an abstract class for a base entity.

2. 2

   What is the difference between HashMap and Hashtable? How does HashMap handle collisions?

   Cover synchronization, null keys/values, and performance. For collisions, explain chaining and treeification in Java 8+. Show you understand internal workings.

3. 3

   Write a Java method to check if a string is a palindrome, ignoring case and non-alphanumeric characters.

   Use two pointers or StringBuilder reverse. Discuss time and space complexity. Handle edge cases like empty string or single character.

4. 4

   Explain the concept of immutability in Java. How would you create an immutable class?

   Mention final class, private final fields, no setters, and defensive copying. Give an example like String or a custom class.

Spring Framework and Database

1. 5

   What is dependency injection in Spring? How does it help in writing testable code?

   Explain inversion of control, constructor vs setter injection, and how it allows mocking dependencies in unit tests. Relate to real project benefits.

2. 6

   How would you design a REST API for a simple employee management system? List the endpoints and HTTP methods.

   Cover CRUD operations: GET /employees, GET /employees/{id}, POST /employees, PUT /employees/{id}, DELETE /employees/{id}. Mention status codes and request/response formats.

3. 7

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

   Use subquery with LIMIT/OFFSET or window function like DENSE_RANK(). Explain the logic and handle ties or nulls.

4. 8

   What is the difference between @Component, @Service, and @Repository annotations in Spring?

   Explain that they are specializations of @Component for different layers, with @Repository adding exception translation. Mention stereotype annotations and their use in component scanning.

Practical Scenarios and Problem Solving

1. 9

   You are asked to fix a bug where an API returns a 500 error only in production but works in local. How do you approach debugging?

   Talk about checking logs, environment differences (config, DB versions), reproducing the issue, and using tools like Postman or debuggers. Emphasize systematic isolation.

2. 10

   Your team needs to add a new feature to an existing Spring Boot application. How do you ensure your changes do not break existing functionality?

   Mention writing unit tests, running integration tests, using Git branches, and code reviews. Highlight the importance of regression testing.

3. 11

   You have a list of 1 million integers and need to find the top 10 largest. How would you do it efficiently in Java?

   Use a min-heap of size 10 or sort and take last 10 (but heap is more efficient). Discuss time complexity O(n log k) and space O(k).

4. 12

   How would you handle a situation where you are stuck on a coding problem for over an hour during a project?

   Show you would research (documentation, Stack Overflow), ask a teammate for help, or take a break. Emphasize time management and not wasting team resources.

Behavioural and HR Questions

1. 13

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

   Use STAR method. Highlight collaboration, your specific contribution, and the outcome. Even college projects count.

2. 14

   Why do you want to work as a Java Developer at an IT services company like Chargebee India?

   Show interest in the company's domain (e.g., subscription billing) and the role. Mention growth opportunities and your eagerness to learn.

3. 15

   How do you handle tight deadlines or pressure? Give an example.

   Describe a situation from college or internship where you prioritized tasks, communicated with stakeholders, and delivered. Focus on calm and planning.

4. 16

   Are you willing to relocate or work in different shifts if required?

   Be honest but flexible. If you are open, say yes and express adaptability. If not, explain your constraints professionally.