Infosys Senior Java Developer Interview Questions and Answers

Memory leaks occur when a program allocates memory but does not release it, leading to inefficient memory usage.

• Use tools like profilers to identify memory leaks in Java applications.

• Avoid creating unnecessary objects and ensure proper garbage collection.

• Avoid static references to objects that can prevent them from being garbage collected.

• Close resources like files, database connections, and streams after use to preven...read more

Maven defines six scopes for dependencies: compile, provided, runtime, test, system, and import, each serving different purposes.

• 1. Compile: Default scope, available in all classpaths. Example: <scope>compile</scope>

• 2. Provided: Used when the dependency is provided by the JDK or a container. Example: <scope>provided</scope>

• 3. Runtime: Available at runtime but not at compile time. Example: <sc...read more

Comparable is an interface used for natural ordering, while Comparator is an interface used for custom ordering.

• Comparable is implemented by the class itself to define the natural ordering of objects.

• Comparator is implemented by a separate class to define custom ordering of objects.

• Example: String class implements Comparable interface for natural ordering, while Collections class uses Comparator for custom sorting.

I have over 10 years of experience in Java development, working on various projects and technologies.

• 10+ years of experience in Java development

• Worked on various projects and technologies

• Strong understanding of software development lifecycle

• Experience with frameworks like Spring and Hibernate

• Knowledge of design patterns and best practices

To set up a Spring-Boot project with only OS and JDK, you need to install Maven and then create a new project using Spring Initializr.

• Install Apache Maven to manage dependencies and build the project

• Use Spring Initializr to generate a new Spring Boot project with required dependencies

• Import the project into your IDE and start coding

Commonly used Spring Boot annotations include @RestController, @Autowired, @RequestMapping, @Service, @Component, @Repository.

• @RestController - Used to define RESTful web services.

• @Autowired - Used for automatic dependency injection.

• @RequestMapping - Used to map web requests to specific handler methods.

• @Service - Used to indicate that a class is a service component.

• @Component - Used to indicate that a class is a Spring...read more

I recently developed a REST API for a banking application to handle customer transactions.

• Implemented CRUD operations for customer accounts and transactions

• Used Spring Boot framework for building the API

• Secured API endpoints using OAuth 2.0 authentication

• Utilized Swagger for API documentation

Pagination in APIs is achieved by using query parameters like page number and page size.

• Use query parameters like 'page' and 'size' to specify the page number and number of items per page.

• Implement logic in the backend to fetch and return only the specified page of data.

• Calculate the total number of pages based on the total number of items and page size.

• Include links to navigate to the next and previous pages in the AP...read more

Implement pagination in UI by limiting results to 10 per page.

• Implement pagination logic in UI to display 10 results per page.

• Use backend query parameters like 'offset' and 'limit' to fetch specific results.

• Utilize front-end frameworks like React or Angular for efficient pagination implementation.

Actuators in Spring Boot are built-in tools that help monitor and manage the application.

• Actuators provide endpoints to monitor application health, metrics, info, etc.

• They can be used to interact with the application at runtime.

• Examples include /actuator/health, /actuator/metrics, /actuator/info, etc.

pom.xml is a configuration file in a Maven project that defines project dependencies, build settings, and plugins.

• Defines project dependencies and their versions

• Specifies build settings such as source directory, target directory, and compiler version

• Configures plugins for various tasks like compiling code, running tests, packaging the project

• Helps in managing project lifecycle phases like clean, compile, test, package,...read more

GET is used to request data from a specified resource, while POST is used to submit data to a specified resource.

• GET requests are idempotent, meaning they can be repeated without changing the result, while POST requests are not.

• GET requests can be cached, bookmarked, and shared, while POST requests cannot.

• GET requests have a limit on the amount of data that can be sent, while POST requests do not have such limitations.

• ...read more

Yes, by implementing a RESTful API with different HTTP methods for each operation.

• Implement a RESTful API with different endpoints for each operation: GET for retrieving data, POST for supplying data, and DELETE for deleting data.

• For example, GET /data to retrieve data, POST /data to supply data, and DELETE /data/{id} to delete data by ID.

• Use proper HTTP methods and status codes to handle each operation effectively.

Yes, I have experience working with cloud technologies such as AWS, Azure, and Google Cloud Platform.

• Experience with AWS, Azure, and Google Cloud Platform

• Deploying applications on cloud infrastructure

• Working with cloud services like EC2, S3, and RDS

I have worked with technologies such as Spring Boot, Hibernate, Angular, and Docker in various projects.

• Spring Boot

• Hibernate

• Angular

• Docker

Tomcat and Spring Boot versions are independent of each other, but they can be compatible with each other.

• Tomcat versions can range from 7.x to 10.x, with the latest stable version being 10.0.12.

• Spring Boot versions are typically aligned with Spring Framework versions, with the latest stable version being 2.5.4.

• It is important to ensure compatibility between the Tomcat and Spring Boot versions being used in a project.