Morningstar Senior Software Engineer Interview Questions and Answers

Developed a web application for online shopping with user authentication and payment gateway integration.

• Used React.js for front-end development

• Implemented user authentication using JWT tokens

• Integrated Stripe API for payment processing

Optimization techniques are methods used to improve the efficiency and performance of software applications.

• Use of algorithms like dynamic programming and greedy algorithms

• Profiling and performance tuning to identify bottlenecks

• Code refactoring to improve readability and maintainability

• Utilizing caching and memoization for faster access to data

• Parallel processing and multi-threading for improved concurrency

Pagination in SQL allows for displaying a subset of query results at a time.

• Use LIMIT and OFFSET clauses in SQL queries to implement pagination.

• LIMIT specifies the maximum number of rows to return.

• OFFSET specifies the number of rows to skip before starting to return rows.

Threads and tasks are both used in multiprocessing, but have different characteristics and use cases.

• Threads are lightweight processes within a single process, sharing memory space. They are managed by the operating system.

• Tasks are units of work that can be executed asynchronously. They are typically managed by a task scheduler.

• Threads are suitable for parallel processing and improving performance, while tasks are use...read more

ViewBag is used to pass data from controller to view, while TempData is used to pass data between controller actions.

• ViewBag is a dynamic property that allows you to pass data from controller to view

• TempData is a dictionary object that allows you to pass data between controller actions

• ViewBag is not type-safe and requires typecasting, while TempData is type-safe

• ViewBag data is lost if redirection occurs, while TempData...read more

Abstract classes can have both abstract and non-abstract methods, while interfaces can only have abstract methods.

• Abstract classes can have constructors, fields, and non-abstract methods.

• Interfaces can only have abstract methods and constants.

• A class can implement multiple interfaces but can only inherit from one abstract class.

Primary is used to define a primary bean when multiple beans of the same type are present, while Qualifier is used to specify which bean to autowire when multiple beans of the same type are present.

• Primary annotation is used to give a higher preference to a bean when multiple beans of the same type are present in the Spring application context.

• Qualifier annotation is used to specify which bean to autowire when multiple...read more

Fault tolerance in Microservices can be achieved through redundancy, graceful degradation, and circuit breakers.

• Implementing redundancy by having multiple instances of each microservice running to handle failures.

• Using graceful degradation to ensure that the system can still function even if certain microservices are unavailable.

• Utilizing circuit breakers to prevent cascading failures by temporarily stopping requests t...read more

Implementing Spring Security involves configuring security settings in the Spring application.

• Add Spring Security dependency in pom.xml

• Configure security settings in SecurityConfig class

• Define user roles and permissions

• Use annotations like @EnableWebSecurity and @Secured

OAuth 2 is an authorization framework that allows a third-party application to obtain limited access to an HTTP service.

• OAuth 2 is used for delegated access, allowing a user to grant a third-party application access to their resources without sharing their credentials.

• It involves the use of access tokens, which are issued by the authorization server after the user authenticates and authorizes the application.

• OAuth 2 su...read more

Java uses automatic memory management through garbage collection to allocate and deallocate memory.

• Java uses garbage collection to automatically manage memory by deallocating objects that are no longer needed.

• The JVM has a heap where objects are allocated and garbage collection is performed to reclaim memory.

• Java provides the 'finalize()' method for objects to perform cleanup before they are garbage collected.

• Memory le...read more

Different types of garbage collection algorithms in software development.

• Mark and Sweep: Identifies and removes unreachable objects.

• Generational: Divides objects into different generations based on age.

• Parallel: Uses multiple threads to perform garbage collection concurrently.

• Incremental: Spreads garbage collection work over multiple cycles to reduce pause times.

Executors are a class that provides factory and utility methods for Executor, ExecutorService is an interface that represents an asynchronous execution service.

• Executors class provides factory and utility methods for Executor interface

• ExecutorService is an interface that represents an asynchronous execution service

• ExecutorService extends Executor interface

• ExecutorService provides methods to manage termination and produ...read more

Find duplicates in an ArrayList of strings.

• Iterate through the ArrayList and use a HashSet to keep track of seen elements.

• If an element is already in the HashSet, it is a duplicate.

• Store the duplicates in a separate ArrayList or print them directly.