Luxoft Senior Java Developer Interview Questions and Answers

Garbage collection is an automatic memory management process that frees up memory occupied by objects that are no longer in use.

• Garbage collection is performed by the JVM.

• It helps prevent memory leaks and improves application performance.

• There are different types of garbage collectors such as serial, parallel, CMS, and G1.

• Garbage collection can cause pauses in the application, which can be minimized by tuning the JVM parameters.

• It is important to write efficient and optimized...read more

Hash collusion is when two different inputs produce the same hash value.

• It is a security vulnerability in hash functions.

• Attackers can exploit this vulnerability to create a collision attack.

• For example, an attacker can create a malicious file with the same hash value as a legitimate file to bypass security checks.

Saga design pattern is used to manage long-lived transactions between microservices.

• It ensures that all services involved in a transaction are either committed or rolled back together.

• It uses a sequence of local transactions to achieve global consistency.

• It can be implemented using either choreography or orchestration.

• Example: A customer places an order, which involves multiple microservices such as inventory, payment, and shipping. Saga pattern ensures that if any of these s...read more

Sessions in Hibernate are used to manage the interaction between the application and the database.

• A session is a single-threaded object that represents a connection between the application and the database.

• It is responsible for managing the persistence of objects, executing queries, and providing transactional support.

• A session can be obtained from a session factory and should be closed when no longer needed.

• Example: Session session = sessionFactory.openSession();

• Example: ses...read more

Microservices design pattern is an architectural approach to building software applications as a collection of small, independent services.

• Microservices are independently deployable and scalable

• Each microservice focuses on a specific business capability

• Communication between microservices is done through APIs

• Microservices can be developed using different programming languages and technologies

• Examples of companies using microservices include Netflix, Amazon, and Uber

ConcurrentSkipListMap is a concurrent, sorted map implementation in Java.

• ConcurrentSkipListMap is a concurrent version of SkipListMap, which is a sorted map implementation based on skip list data structure.

• It allows multiple threads to access and modify the map concurrently.

• It provides logarithmic time complexity for most operations, making it efficient for concurrent access.

• Example: ConcurrentSkipListMap map = new ConcurrentSkipListMap<>();