Fidelity Investments Lead Developer Interview Questions, Process, and Tips

3 hacker rank questions easy to medium level asked to solve in 60 mins.

Q1. Design patterns java when and what to use
Ans. 
Design patterns in Java are reusable solutions to common software design problems.
• Design patterns should be used when there is a recurring problem in software design.

• Design patterns can improve code readability, maintainability, and scalability.

• Examples of design patterns include Singleton, Factory, Observer, and Decorator.

• It's important to choose the right design pattern for the specific problem at hand.

• Design pattern...read more
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Q2. OOPs concepts deep dive - scenario based questions
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Q3. Java 8 streams - how they function internally
Ans. 
Java 8 streams are functional programming constructs that allow for efficient processing of large data sets.
• Streams are composed of a source, intermediate operations, and a terminal operation.

• Intermediate operations include filter, map, and sorted, and are lazily evaluated.

• Terminal operations trigger the evaluation of the stream and include forEach, reduce, and collect.

• Streams can be parallelized for even greater perfo...read more
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Q4. Difference between fixed thread pool and cached thread pool
Ans. 
Fixed thread pool has a fixed number of threads while cached thread pool creates new threads as needed.
• Fixed thread pool is suitable for tasks with a known number of threads

• Cached thread pool is suitable for tasks with unknown number of threads

• Fixed thread pool can cause resource wastage if the number of threads is too high

• Cached thread pool can cause performance issues if the number of threads is too high

• Example: Fixe...read more
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Q1. All spring boot scenario based questions
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Q2. How to handle spring app config
Ans. 
Spring app config can be handled using various methods such as XML configuration, Java configuration, and annotation-based configuration.
• XML configuration involves creating an XML file and defining beans and their dependencies.

• Java configuration involves creating a Java class and using annotations to define beans and their dependencies.

• Annotation-based configuration involves using annotations to define beans and their ...read more
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Q3. How to improve application performance
Ans. 
Improving application performance requires optimizing code, database queries, and server resources.
• Identify and fix slow database queries

• Use caching to reduce server load

• Optimize code by reducing unnecessary loops and improving algorithms

• Use a content delivery network (CDN) to reduce server load

• Upgrade server hardware or use cloud-based resources

• Minimize HTTP requests and reduce file sizes for faster page load times
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Q4. Microservices communication patterns
Ans. 
Microservices use various communication patterns like synchronous, asynchronous, event-driven, and message-based.
• Synchronous communication involves direct request-response interactions between services.

• Asynchronous communication uses messaging systems like RabbitMQ or Kafka to decouple services.

• Event-driven communication involves services publishing events to a message broker, which other services can subscribe to.

• Mess...read more
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Q5. How to use cache with spring boot
Ans. 
Using cache with Spring Boot
• Add @EnableCaching annotation to main class

• Add @Cacheable annotation to methods that need caching

• Configure cache properties in application.properties file

• Use CacheManager to manage caches

• Example: @Cacheable(value = "users", key = "#id")
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Q6. How to use async in spring boot - advantages
Ans. 
Async in Spring Boot allows non-blocking I/O operations, improving application performance.
• Async enables parallel processing of requests, improving throughput.

• It allows the application to handle more requests with the same resources.

• It reduces the response time for long-running operations.

• Use @Async annotation to mark methods as asynchronous.

• Use CompletableFuture to handle async results.

• Example: @Async public Completab...read more
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Q7. How mvc pattern works in spring mvc
Ans. 
Spring MVC follows the Model-View-Controller (MVC) pattern for building web applications.
• Model represents the data and business logic

• View renders the model data and provides user interface

• Controller handles user requests, updates model and selects view

• Spring MVC provides DispatcherServlet as front controller

• RequestMapping annotation maps URL to controller method

• ModelAndView object returns model data and view name
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Q8. What is filter and why it is required
Ans. 
Filter is a method used to extract specific data from a larger set based on certain criteria.
• Filter is required to extract specific data from a larger set.

• It is used to reduce the amount of data that needs to be processed.

• Filter can be applied to arrays, objects, and even strings.

• Examples include filtering out all even numbers from an array or all emails from a list that contain a specific keyword.
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Q9. How authentication and authorization works - oauth2 way of handling them
Ans. 
OAuth2 is a protocol for authentication and authorization that allows third-party applications to access user data without sharing passwords.
• OAuth2 provides a secure and standardized way for users to grant access to their resources to third-party applications.

• It involves the exchange of tokens between the user, the third-party application, and the resource server.

• Authentication is handled by the authorization server, w...read more
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Q10. Difference between jwt and oauth2, how to secure rest endpoints
Ans. 
JWT is a token format while OAuth2 is a protocol. Both can be used to secure REST endpoints.
• JWT is a self-contained token that contains user information and can be used for authentication and authorization.

• OAuth2 is a protocol that allows third-party applications to access user data without sharing passwords.

• To secure REST endpoints, both JWT and OAuth2 can be used depending on the use case.

• For example, JWT can be used...read more
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Q11. Java 8 problem solving
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Hacker rank test. Which having avg programing question

Q1. Java question with coding question . Mostly will ask from the resume the skill has mention and based on skill the hiring is happing
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