Скачать или смотреть Crack HCL 2nd Round Technical Java Interview in 2025 !🔥 Real Interview Questions for 3+ year

In this video, we will discuss about 2nd technical round interview questions and answers in the HCL company for backend developer profile.

Q1. What are the main features introduced in Java 8 ?
Ans:
1.Lambda Expressions
2. Functional Interfaces
3. Stream API
4. Default and Static methods in Interfaces
5. java.time API (Date and Time)
6. Optional class
7. CompletableFuture and Parallel Streams
8. Method references

Q2. What is a Lambda Expression?
Ans:
lambda expression is a short block of code which takes in parameters and returns a value. Lambda expressions are used primarily to define the implementation of a functional interface (an interface with only one abstract method).Syntax of Lambda Expression:(parameters) -expressionor(parameters) - {
// statements
return value;
}

Q3. Why Lambda Expressions Were Introduced?
Ans:
Lambda expressions were introduced to:
Simplify code by enabling functional programming features
Removing boilerplate
Improving readability
Providing a better way to work with functional interfaces and collections.

Q4. What is a Functional Interface?
Ans:
An interface with exactly one abstract method.Examples: Runnable, Callable, Comparator, Function, Predicate, etc.
You can use @FunctionalInterface annotation for clarity.

Benefit
Explanation
Enables lambda expressions
Foundation for functional programming in Java
Simplifies code
Less boilerplate (no anonymous inner classes)
Stream API integration
Used with map, filter, forEach, etc.
Enables behavior as data
You can pass behavior (methods) as parameters
Works with built-in interfaces
Like Function, Predicate, etc.

Q5. What is difference between map and flatMap?
Ans:
The map() method in Java Stream API is used to transform each element of a stream into another object, applying a function to each element in the stream.Purpose of map():
Used to transform or convert data.
Does not modify the original stream but creates a new stream.
The flatMap() method is used to transform and flatten complex or nested data structures—especially when each element of a stream contains a collection (e.g., List, Set, Stream).Purpose of flatMap:
Use flatMap() when each element in the original stream needs to be converted to a stream, and then flattened into a single stream.

Q9. What is Monolithic Architecture?
Ans:
A monolithic application is built as a single, unified unit. All the components—like UI, business logic, data access layer—are combined and run as a single application.
Example:A large e-commerce application where all features like product catalog, user management, payment, and order processing are tightly integrated and deployed together in one WAR/JAR file.

Q10. What is Microservices Architecture?
Ans:
A microservices architecture structures an application as a collection of small, loosely coupled services, each responsible for a specific business function and running independently.
Each service:
Has its own codebase
Can use a different technology stack
Communicates via APIs (REST, gRPC, messaging)
Can be developed, deployed, and scaled independently
Example:An e-commerce system with:
User-Service
Product-Service
Payment-Service
Order-Service — each deployed separately and communicating via REST APIs or events.

Q12. What is a Circuit Breaker? Why do we use it in microservices?
Ans: A Circuit Breaker is a design pattern used in microservices architecture to prevent repeated failures in a distributed system by gracefully handling service outages.


Why do we use it in microservice?Microservices are distributed systems that talk to each other over a network. If Service A depends on Service B, and Service B is down or slow, Service A’s performance will degrade too — possibly leading to a cascade failure across the system.

Q13. How do you ensure fault tolerance in microservices?
Ans:
Ensuring fault tolerance in microservices means designing your system so that it continues to function properly even if some of its components fail. In distributed systems, failures are inevitable — network issues, service crashes, timeouts, etc. Fault-tolerant microservices absorb these failures and fail gracefully instead of bringing the entire system down.
Key Concepts to Ensure Fault Tolerance in Microservices
Circuit Breaker Pattern
Retry Mechanism
Timeouts
Fallback Methods
Bulkhead Pattern
Load Balancing
Service Discovery and Self-Healing
Health Checks
Asynchronous Communication
Graceful Degradation