Lenovo Java Backend Developer Interview Experience (3 YOE) – Complete Question Breakdown
Summary
I recently appeared for a Backend Developer interview at Lenovo, where I was asked questions spanning Java core concepts, Microservices, System Design, Spring Boot, SQL, Git, and coding problems using the Stream API.
Full Experience
Recently, I appeared for a Backend Developer interview at Lenovo (Tech Stack: Java, Spring Boot, Microservices, MySQL, Apache Kafka, DSA). I’m sharing my experience and some of the questions that were asked — hoping it helps others preparing for similar roles.
Interview Questions (37)
Java 8 New Features
What are the new features introduced in Java 8?
What is a Method Reference?
What is a Method Reference?
Default Methods in Interfaces
What are Default Methods in interfaces?
Intermediate Operations in Streams
Explain Intermediate Operations in Streams.
HTTP Status Code 204
What is HTTP Status Code 204?
HashMap vs Hashtable
Difference between HashMap and Hashtable.
Garbage Collection
What is Garbage Collection and how does it work?
How JWT Works
How does JWT (JSON Web Token) work?
Integrating 3rd-Party APIs
How do you integrate 3rd-party APIs in your project?
Microservices Concept
Explain the concept of Microservices in your project.
Authentication Layer in Architecture
Explain the Authentication Layer in your architecture.
Distributed Transactions: 2PC vs Saga
Distributed transactions – Compare 2PC vs Saga (real production trade-offs).
Debugging Duplicate Payment Transactions
Debugging duplicate payment transactions issue end-to-end.
Design a Rate Limiter
Design a rate limiter handling millions of requests per second.
Architect a Real-time Fraud Detection System
Architect a real-time fraud detection system.
Spring Boot Application Startup Process
What happens internally when a Spring Boot application starts? (Lifecycle & Bean Initialization Flow)
What is @Lazy?
What is @Lazy?
What is @Component?
What is @Component?
What is Component Scanning?
What is Component Scanning?
Global Exception Handling in Spring Boot
How do you handle exceptions globally?
What is JPA?
What is JPA?
Explain Bean Scopes
Explain Bean Scopes.
@RequestParam vs @RequestBody
@RequestParam vs @RequestBody
What is @PathVariable?
What is @PathVariable?
Saga & Circuit Breaker Design Pattern
Saga & Circuit Breaker Design Pattern
SQL: Fetch Records with Offset and Limit
Given a User table with 50 records, write a SQL query to fetch 20 records starting from the 5th row, including only the first and last name.
SQL: INNER JOIN Query
Write an INNER JOIN query between two tables.
Git Usage in Team
How do you use Git in your team?
Git Branching & Merging Strategy
Branching & merging strategy?
JUnit and Mockito Usage
What is the use of JUnit and Mockito in your project?
Calculate Total Revenue using Streams
Calculate total revenue from all orders using Streams.
Find Top 3 Highest-Priced Products using Streams
Find the Top 3 highest-priced products across all orders.
Group Products by Category and Calculate Total Revenue
Group products by category and calculate total revenue per category using Streams.
Find Customers with More Than 3 Orders
Find customers who placed more than 3 orders using Streams.
Identify Most Frequently Sold Product
Identify the most frequently sold product using Streams.
Anagram Check
Determine if two strings are anagrams of each other.
Product of Array Except Self
Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i]. The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer. You must write an algorithm that runs in O(n) time and without using the division operation.