Wipro Digital Java Developer Interview: Rounds, Questions and Preparation

What the job involves

A Java Developer at an Indian IT services company like Wipro Digital builds and maintains enterprise applications for clients across banking, insurance, retail, and healthcare. The work involves writing server-side code using Java and frameworks like Spring Boot, integrating with databases and REST APIs, and fixing bugs in existing systems. Freshers usually start on maintenance or enhancement projects, with close supervision from a senior developer or technical lead.

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 in a service layer?

   Cover that abstract classes can have state and constructors while interfaces define contracts. Mention that in a service layer, interfaces are preferred for loose coupling and testability, while abstract classes help share common logic across services.

2. 2

   Explain how HashMap works internally in Java. Why is it important for a Java Developer working on enterprise applications?

   Explain hashing, buckets, equals and hashCode contract, and collision handling with linked lists or trees. Connect it to performance when caching or grouping large data sets in a client project.

3. 3

   What is the difference between checked and unchecked exceptions? Give an example of each from a real web application.

   Define checked exceptions as compile-time enforced and unchecked as runtime. Give examples like IOException for checked and NullPointerException for unchecked, and mention how Spring Boot handles them with @ExceptionHandler.

4. 4

   How does Spring Boot help you build a REST API faster than plain Java servlets?

   Mention auto-configuration, embedded server, starter dependencies, and annotations like @RestController and @RequestMapping. Explain that it reduces boilerplate and speeds up development on client projects.

Practical Scenarios

1. 5

   You are asked to add a new field to an existing REST API response without breaking the mobile app that consumes it. How do you approach this?

   Talk about backward compatibility, adding the field as optional, versioning the API if needed, and communicating with the client team. Mention testing with existing consumers before deployment.

2. 6

   A production bug shows that a Java service is throwing a NullPointerException intermittently. How do you debug it in a client environment where you cannot restart the server freely?

   Cover reading logs, using thread dumps, adding temporary logging, checking recent code changes, and reproducing in a lower environment. Mention using a debugger or APM tools if available.

3. 7

   Your SQL query is running slowly on a table with millions of rows. What steps do you take to improve its performance?

   Mention checking indexes, avoiding SELECT *, using EXPLAIN plan, reducing joins, and pagination. Talk about coordinating with the DBA and testing the fix in a staging environment.

4. 8

   You need to consume a third-party REST API that sometimes returns errors or times out. How do you make your Java code resilient?

   Discuss retry logic with backoff, timeouts, circuit breaker patterns, and fallback responses. Mention logging failures and alerting so the support team can act.

Project and Coding Discussion

1. 9

   Walk me through a Java project you built in college. What was your role, and what was the most difficult part?

   Use a clear structure: problem, your contribution, technologies, challenges, and outcome. Be honest about what you did personally and what you learned from the difficulty.

2. 10

   How did you test your Java code in your academic project? Did you write unit tests?

   If you wrote JUnit tests, explain what you tested and why. If not, say you tested manually and mention that you have since learned JUnit and understand its importance in enterprise projects.

3. 11

   Write a small Java method to find the second largest number in an array. Explain your logic as you write.

   Use a single pass with two variables for largest and second largest, handle duplicates and edge cases like array length less than two. Explain time complexity as O(n).

4. 12

   You used Git in your project. What is the difference between git merge and git rebase, and which one would you use in a team project?

   Explain that merge preserves history with a merge commit while rebase creates a linear history. Mention that in a shared branch, merge is safer, and rebase is better for cleaning up local commits before pushing.

Behavioural and HR Questions

1. 13

   Indian IT services projects often require working in shifts or relocating to a client location. How do you feel about that?

   Show flexibility and willingness, but be honest about any constraints. Mention that you understand client demands and are open to adjusting as long as you get reasonable notice.

2. 14

   Tell me about a time you had to learn a new technology quickly for a college project or internship. How did you manage?

   Use a specific example, describe your learning approach, and highlight the result. Show that you can self-learn and ask for help when stuck.

3. 15

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

   Talk about asking clarifying questions early, breaking the task into smaller parts, communicating progress, and escalating blockers. Avoid saying you would just guess or work overtime without a plan.

4. 16

   Why do you want to join an IT services company like Wipro Digital rather than a product startup?

   Mention exposure to multiple clients and domains, structured training, and long-term career growth. Connect it to your interest in enterprise Java development and working with large teams.