HashedIn by Deloitte Java Developer Interview Questions and Answers for Experienced

Q1. What is the contract between hashCode and equals method?
Ans. 
The contract between hashCode and equals method is that if two objects are equal according to the equals method, then their hash codes must also be equal.
• hashCode and equals method must be consistent - if two objects are equal according to equals method, their hash codes must be equal

• If two objects have the same hash code, they may or may not be equal according to equals method

• Overriding equals method in a class requir...read more
Answered by AI
View 1 more amswer
Q2. Features introduced in Java 8
Ans. 
Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods in interfaces.
• Lambda expressions allow you to pass functions as arguments.

• Functional interfaces have a single abstract method and can be used with lambda expressions.

• Streams provide a way to work with sequences of elements.

• Default methods allow interfaces to have method implementations.
Answered by AI
Add your answer
Q3. What are the ways to start a thread
Ans. 
Ways to start a thread in Java
• Extending the Thread class and overriding the run() method

• Implementing the Runnable interface and passing it to a Thread object

• Using a thread pool from the Executors class
Answered by AI
Add your answer
Q4. What will happen if you start a thread which is already running
Ans. 
The thread will continue running as it is already active
• The thread will not be started again if it is already running

• Attempting to start a thread that is already running will not have any effect

• The thread will continue its execution without any interruption
Answered by AI
View 1 more amswer
Q5. Explain about the join and sleep method
Ans. 
Join method is used to wait for a thread to finish its execution, while sleep method is used to pause the execution of a thread for a specified amount of time.
• Join method is used to wait for a thread to finish its execution before moving on to the next task.

• Sleep method is used to pause the execution of a thread for a specified amount of time, allowing other threads to run.

• Example: thread1.join() will wait for thread1 ...read more
Answered by AI
Add your answer

One coding question with 40-45 mcq

Q1. 2 coding questions from array
Add your answer
Q2. In given array find the sum a*a+b*b=c*c
Ans. 
Use a nested loop to iterate through the array and check for the sum of squares of two elements equal to the square of a third element.
• Iterate through the array using a nested loop to compare all possible combinations of elements.

• Calculate the sum of squares of two elements and check if it equals the square of a third element.

• Return the elements if a match is found, otherwise continue iterating.
Answered by AI
Add your answer

Q1. Core java questions, springboot, one string coding question
Add your answer

Q1. Exception handling
Add your answer

Contiguous array in java

Q1. Microservices architecture
Add your answer
Q2. Saga design pattern
Add your answer

JOY of energy project checks only solid principles asks question for every letter you type for developing a feature

Q1. 1. How microservices communicate with each other?
Ans. 
Microservices communicate with each other through APIs and messaging protocols.
• Microservices use APIs to communicate with each other.

• Messaging protocols like HTTP, AMQP, and MQTT are used for asynchronous communication.

• Service discovery mechanisms like Eureka and Consul are used to locate services.

• API gateways like Zuul and Kong are used to manage API traffic.

• Event-driven architecture is used for real-time communicatio
Answered by AI
View 1 more amswer
Q2. 2. How do you secure your APIs?
Ans. 
Securing APIs involves implementing authentication, authorization, encryption, and input validation.
• Implement authentication mechanisms like OAuth, JWT, or API keys

• Use authorization to control access to APIs based on user roles and permissions

• Encrypt sensitive data transmitted over the network using HTTPS

• Validate and sanitize input to prevent common security vulnerabilities like SQL injection or cross-site scripting (X
Answered by AI
View 1 more amswer
Q3. 3. Scenario based question on qualifier?
Add your answer
Q4. 4. What is ORM tool?
Ans. 
ORM (Object-Relational Mapping) tool is a software framework that maps objects to relational databases.
• ORM tool simplifies database operations by allowing developers to interact with databases using object-oriented programming.

• It eliminates the need for writing complex SQL queries by providing a higher-level abstraction.

• ORM tools handle tasks like data persistence, retrieval, and mapping between objects and database ta...read more
Answered by AI
View 1 more amswer
Q5. 5. Advantages of hibernate
Ans. 
Hibernate simplifies database programming in Java applications.
• Hibernate provides a simple and efficient way to interact with databases.

• It eliminates the need for writing complex SQL queries.

• It supports object-oriented programming and mapping of Java classes to database tables.

• It provides caching and lazy loading mechanisms for improved performance.

• It supports transaction management and reduces the risk of data corrupt...read more
Answered by AI
Add your answer
Q6. 6. Rest controller vs Controller
Ans. 
Rest controller is used for RESTful web services while Controller is used for traditional web applications.
• Rest controller maps HTTP requests to RESTful web services while Controller maps HTTP requests to traditional web applications.

• Rest controller uses @RestController annotation while Controller uses @Controller annotation.

• Rest controller returns data in JSON or XML format while Controller returns data in HTML format...read more
Answered by AI
Add your answer
Q7. 7. What if i write component in place of service ?
Ans. 
Using component instead of service may cause confusion and errors in the code.
• Components and services are two different concepts in Java development.

• Components are used for UI elements while services are used for business logic.

• Using component instead of service may lead to errors in the code and confusion for other developers.

• For example, if a component is used instead of a service for business logic, it may not have ...read more
Answered by AI
Add your answer
Q8. 8. What is the work of @autowired?
Ans. 
The @Autowired annotation is used to automatically wire beans by matching the data type of the bean with the data type of the property.
• Used to inject dependencies automatically

• Reduces the need for manual bean configuration

• Can be used with constructors, fields, and methods

• Can be used with @Qualifier to specify which bean to wire
Answered by AI
Add your answer
Q9. 9. What is Eureka server ? Default port
Ans. 
Eureka server is a service registry that enables microservices to discover and communicate with each other.
• Eureka server is a component of Netflix's OSS suite.

• It allows services to register themselves and discover other services.

• It uses a REST API for communication.

• Default port is 8761.
Answered by AI
Add your answer
Q10. 10. What is circuit breaker? Hystrix
Ans. 
Circuit breaker is a design pattern used to prevent cascading failures in distributed systems. Hystrix is a popular implementation.
• Circuit breaker monitors the availability of a service and trips if the service fails repeatedly.

• It helps to prevent cascading failures by failing fast and providing fallback options.

• Hystrix is a popular implementation of circuit breaker pattern in Java.

• It provides features like request cac
Answered by AI
Add your answer
Q11. 11. What are ternary operators ?
Ans. 
Ternary operators are conditional operators that evaluate a boolean expression and return one of two values based on the result.
• Ternary operators are written in the form of 'condition ? value1 : value2'

• If the condition is true, the operator returns value1, otherwise it returns value2

• Ternary operators can be used as a shorthand for if-else statements

• Example: int x = (a > b) ? a : b; // assigns the larger value of a and
Answered by AI
Add your answer
Q12. 12. How to write the entity class?
Ans. 
Entity class represents a table in a database and its attributes as fields.
• Define class with @Entity annotation

• Add @Id annotation to primary key field

• Add @Column annotation to map fields to table columns

• Implement getters and setters

• Override equals() and hashCode() methods
Answered by AI
View 1 more amswer
Q13. 13. What is crud vs Jpa ?
Ans. 
CRUD is a basic operation for data manipulation while JPA is a Java specification for ORM.
• CRUD stands for Create, Read, Update, and Delete which are basic operations for data manipulation.

• JPA is a Java specification for Object-Relational Mapping (ORM) which provides a way to map Java objects to relational database tables.

• JPA provides a higher level of abstraction and simplifies the data access layer by providing an API...read more
Answered by AI
Add your answer

Q1. Basic Questions about Springboot
Add your answer
Q2. Basic Questions about Java8
Add your answer