HCLTech Interview Questions, Process, and Tips

A controller is a component that handles incoming requests and returns a response, while a REST controller specifically handles RESTful requests.

• A controller is responsible for handling various types of requests, such as HTTP, WebSocket, etc.

• A REST controller is a type of controller that specifically handles RESTful requests, which follow the principles of Representational State Transfer (REST).

• REST controllers typical...read more

A functional interface is an interface that has only one abstract method.

• Functional interfaces are used in lambda expressions and method references.

• They can have default methods and static methods.

• Examples include Runnable, Comparator, and Function interfaces.

• Functional interfaces can be annotated with @FunctionalInterface annotation.

Lambda expression is a concise way to represent anonymous functions in programming languages.

• Lambda expressions are commonly used in functional programming languages.

• They can be used to create functions on the fly without having to define them explicitly.

• Lambda expressions are often used in higher-order functions, such as map, filter, and reduce.

• They can also be used to create closures, which are functions that capture...read more

Exception propagation is the process of passing an exception up the call stack to be handled by a higher-level method.

• Exceptions are thrown when an error occurs in a method.

• If the exception is not caught and handled within the method, it is propagated up the call stack.

• Each method in the call stack has the option to catch and handle the exception or propagate it further up.

• If the exception reaches the top of the call s...read more

get() method returns null if the object is not found in the cache or database, while load() method throws an exception.

• get() method is eager loading while load() method is lazy loading.

• get() method returns the object from the database or cache while load() method returns a proxy object.

• get() method is slower than load() method.

• get() method is used when we are not sure if the object exists in the database or cache while...read more

Method overriding is when a subclass provides its own implementation of a method that is already defined in its superclass.

• Method overriding is used to achieve runtime polymorphism.

• The method signature (name, parameters, return type) must be the same in both the superclass and subclass.

• The access level of the overriding method cannot be more restrictive than the overridden method.

• Example: class Dog extends Animal { pub...read more

IOC and DI are design patterns used in Spring framework for loose coupling and dependency injection.

• IOC (Inversion of Control) is a design pattern where the control of object creation and lifecycle is handed over to a container or framework.

• DI (Dependency Injection) is a design pattern where the dependencies of an object are injected into it by an external entity, rather than the object creating them itself.

• Spring fram...read more

HashMap is a data structure that stores key-value pairs and uses hashing to retrieve values quickly.

• HashMap uses an array of buckets to store key-value pairs

• Each bucket contains a linked list of entries with the same hash code

• When a key-value pair is added, its hash code is used to determine the bucket and added to the linked list

• When a value is retrieved, its hash code is used to find the bucket and search the linked ...read more

Spring Boot provides rapid application development and microservices architecture.

• Easy configuration and setup

• Embedded servers for faster development

• Auto-configuration of dependencies

• Supports multiple data sources

• Actuator for monitoring and managing applications

• Simplifies development of RESTful web services

• Enables building of microservices architecture

• Provides a wide range of plugins and extensions

• Reduces boilerplate c

Developed a real-time data processing system for a financial institution

• Implemented a distributed system using Apache Kafka and Apache Storm

• Designed a fault-tolerant architecture with multiple redundancy layers

• Optimized the system for high throughput and low latency

• Provided real-time monitoring and alerting using Grafana and Prometheus

To make a hotel booking app in ReactJS

• Create a form to input booking details

• Use a calendar component to select dates

• Display available rooms and prices

• Implement payment gateway

• Include user authentication and booking history