10+ DS Group Interview Questions and Answers

Yes, we can write procedures in String Data JPA to handle complex databases in Spring Data JPA persistence.

• Use @Procedure annotation to call stored procedures in Spring Data JPA.

• Define the stored procedure in the database and then call it using the @Procedure annotation in the repository interface.

• Handle complex database operations by writing custom queries or using native queries in Spring Data JPA.

Java 8 introduced new features like lambda expressions, Stream API, default methods, and more.

• Lambda expressions allow functional programming in Java.

• Stream API provides a way to work with collections in a more functional style.

• Default methods allow interfaces to have method implementations.

• Java 8 also introduced the new Date and Time API, Nashorn JavaScript engine, and more.

• MetaSpace in Java 8 is a replacement for the permanent generation in Java 7, used for storing class me...read more

Java 8 introduced several enhancements to HashMap including performance improvements and new methods.

• Java 8 introduced the 'compute', 'computeIfAbsent', and 'computeIfPresent' methods for HashMap.

• The 'forEach' method was added to HashMap in Java 8 for iterating over key-value pairs.

• Java 8 also introduced the 'merge' method for combining values in case of duplicate keys.

Race condition occurs when multiple threads try to access and modify the same resource simultaneously, while deadlock occurs when two or more threads are waiting for each other to release resources.

• Race condition is a situation in which the outcome of a program depends on the order of execution of its threads.

• Deadlock is a situation where two or more threads are blocked forever, waiting for each other to release resources.

• Race condition can lead to unpredictable behavior and ...read more

Interprocess Communication in Microservices architecture is typically achieved through lightweight protocols like HTTP or messaging queues.

• Microservices communicate with each other using RESTful APIs over HTTP.

• Message brokers like Kafka or RabbitMQ are used for asynchronous communication between microservices.

• Service mesh tools like Istio can be used to manage communication between microservices.

• gRPC can be used for high-performance, low-latency communication between microser...read more

I have implemented try-catch blocks for handling exceptions in my project.

• Used try-catch blocks to catch exceptions and handle them gracefully

• Implemented specific catch blocks for different types of exceptions

• Utilized finally block for cleanup operations after exception handling

Yes, unit testing is essential in my projects to ensure code quality and identify bugs early on.

• Yes, I have experience with unit testing in my projects.

• Unit testing helps in identifying bugs early in the development process.

• It ensures code quality and helps in maintaining code integrity.

• Unit tests also serve as documentation for the codebase.

• Examples: JUnit, Mockito, TestNG.

ResponseState and ServerState are different states in a software system that represent different aspects of the system's functionality.

• ResponseState typically refers to the state of a response object in a software system, indicating whether the response was successful, failed, or pending.

• ServerState, on the other hand, refers to the state of the server in a software system, indicating whether the server is running, stopped, or experiencing issues.

• ResponseState is more focused...read more

ConcurrentModificationException is thrown when an object is modified concurrently while iterating over it.

• Occurs when a collection is modified while being iterated over using an iterator

• Can be avoided by using ConcurrentHashMap or CopyOnWriteArrayList

• Example: ArrayList being modified while iterating over it

The main difference between @EnableMock and @Spy in Junit5 is that @EnableMock creates a mock object while @Spy creates a spy object.

• The @EnableMock annotation is used to create a mock object for a class or interface, allowing you to define its behavior using Mockito.

• The @Spy annotation is used to create a spy object, which is a real object with some mock behavior. It allows you to mock specific methods while calling the real methods of the object.

• Mock objects created with @E...read more

The main difference between @PutMapping and @PatchMapping is the level of data that is updated.

• PutMapping is used to update an entire resource, while PatchMapping is used to update only specific fields of a resource.

• PutMapping replaces the entire resource with the new data provided, while PatchMapping updates only the specified fields.

• PutMapping is idempotent, meaning multiple identical requests will have the same effect as a single request, while PatchMapping may not be idem...read more