Infosys Java Software Developer Interview Questions and Answers

Q1. Explain oops concepts
Ans. 
OOPs concepts are fundamental principles of object-oriented programming such as inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implemen...read more
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Q2. Java8 new futures
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Q1. What is difference between abstract class and interface
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructor, fields, and methods, while interface cannot have any of these.

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

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for classes to im...read more
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Q2. What is difference between arraist and linked list
Ans. 
Arrays store elements in contiguous memory locations, while linked lists store elements in nodes with pointers to the next node.
• Arrays have fixed size, while linked lists can dynamically grow or shrink.

• Accessing elements in arrays is faster (O(1)), while accessing elements in linked lists is slower (O(n)).

• Inserting or deleting elements in arrays can be inefficient as it may require shifting elements, while in linked li
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Q1. Q1) What version of Java Are you currently using in your Project? Q2) What are the features Of Java 8? Q3) What is MetaSpace in java 8 Q) What is Spring Exeector Framework? Q)
Ans. 
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...read more
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Q2. Q4) What is the Changes w.r.t Hashmap in java 8 over java 7?
Ans. 
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.
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Q3. Q5) What is the difference between Race Condition and Deadlock in java?
Ans. 
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 resour...read more
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Q4. Q6) What is the ResponseState and ServerState Difference?
Ans. 
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, sto...read more
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Q5. Q7) What is exception handling mechanism which you are implemented in your project?
Ans. 
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
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Q6. Q8 ) What is ConcurrentModificationException In Java?
Ans. 
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
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Q7. Q9) Do you done unit testing In your project? How Unit testing is significant in your project?
Ans. 
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.
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Q8. Q10) What is difference Between @EnableMock and @Spy in Junit5?
Ans. 
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 t...read more
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Q9. Q11) How do you secure your REST API's
Ans. 
Securing REST API's involves using authentication, authorization, encryption, and input validation.
• Use authentication mechanisms like OAuth, JWT, or API keys to verify the identity of clients accessing the API.

• Implement authorization to control what actions different users can perform on the API.

• Encrypt data transmission using HTTPS to prevent eavesdropping and man-in-the-middle attacks.

• Validate and sanitize input data...read more
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Q10. Q12) What is difference between @PutMapping and @PatchMapping?
Ans. 
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 effe...read more
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Q11. Q13) How the Interprocess Communication is happened in the Microservices architecture?
Ans. 
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 hi...read more
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Q12. Q14) Can We write Procedures in String Data JPA? How to handle complex database in Spring Data JPA persistence? using Procedures ---> Ans : Yes
Ans. 
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.
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Q1. Use of spring-boot dev tools
Ans. 
Spring Boot Dev Tools is a set of utilities that help in development and debugging of Spring Boot applications.
• Spring Boot Dev Tools provides automatic restart of the application when changes are detected in the classpath.

• It enables live reloading of static resources like HTML, CSS, and JavaScript without restarting the server.

• Dev Tools also enhances the developer experience by providing additional features like remote...read more
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Q2. Synchronized collections
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Q3. Session Factory in Hibernate
Ans. 
Session Factory is a factory class that creates Session objects for Hibernate.
• Session Factory is responsible for creating and managing Session objects.

• It is a thread-safe object and should be created only once per application.

• It is typically created during application startup and closed during shutdown.

• It is configured with database connection details and Hibernate properties.

• Example: SessionFactory sessionFactory = ne...read more
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Q4. Java Generics knowledge
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Logical aptitude.
Spatial aptitude.
Organisational aptitude.
Physical aptitude.

Why they chose your company.
How your product solved the problem clients faced.
The measurable results of the service provided.

Q1. Self introduction for
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Q2. Introduction your self
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Q3. Why do you choose this company
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Q4. I'm like all food my
Ans. Favourite food is biriyani it's my All time favourite
Answered Anonymously
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Q5. That all when I'm thinking
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Group discussion means one of the news project will be comes we're discussing about that project it's is group discussion

General knowledge questions and skills related questions

Q1. Interview by tech Mahindra HR related to java, introduction, positive points, negative points and why they are hired me
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Q2. Why they are hired me in their company?
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Q3. Self Introduction, positive points and negative points
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