Jforce Solutions Java Developer Interview Questions and Answers

Q1. No one showed up to interview
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Q2. Even they don’t responded to my mails
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Implementation of the Spring security

Q1. What is hashmap
Ans. 
HashMap is a data structure in Java that stores key-value pairs and allows fast retrieval of values based on keys.
• HashMap implements the Map interface in Java

• It allows null keys and values

• Keys in a HashMap must be unique

• Example: HashMap map = new HashMap<>()
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Q2. Internal Working of hashmap
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HashMap is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values.
• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where it will be stored.

• If multiple keys hash to the same index, a linked list is used to handle collisions.

• HashMap uses the hashCode() method of keys to calc...read more
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Q3. Compare Throw vs Throws
Ans. 
Throw is used to explicitly throw an exception in a method, while Throws is used to declare the exceptions that a method may throw.
• Throw is used within a method to throw an exception explicitly.

• Throws is used in the method signature to declare the exceptions that the method may throw.

• Throw is followed by an instance of Throwable class, while Throws is followed by the exception class names separated by commas.

• Example: t...read more
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Q4. Array vs Arraylist
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Arrays are fixed in size, while ArrayLists can dynamically resize. ArrayLists provide more flexibility and functionality.
• Arrays have a fixed size, while ArrayLists can dynamically resize.

• ArrayLists can easily add, remove, or modify elements, while arrays require manual shifting of elements.

• Arrays use [] syntax for declaration and initialization, while ArrayLists use the ArrayList class from the Java Collections framewo
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Q5. Arraylist vs LinkedList/Vector
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ArrayList is resizable array implementation, LinkedList is doubly linked list implementation, Vector is synchronized version of ArrayList.
• ArrayList is faster for accessing elements, LinkedList is faster for adding/removing elements in middle.

• ArrayList uses less memory than LinkedList due to contiguous memory allocation.

• Vector is thread-safe but slower than ArrayList due to synchronization overhead.
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Q6. Write a code for Iterate hashmap using iterator
Ans. 
Iterate through a hashmap using an iterator in Java
• Create an iterator using the entrySet() method of the hashmap

• Use a while loop to iterate through the hashmap entries

• Access the key and value of each entry using the getKey() and getValue() methods
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Q1. What are the advantages of spring boot
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Spring Boot provides a simplified way to create stand-alone, production-grade Spring-based Applications.
• Rapid application development

• Embedded server for easy deployment

• Auto-configuration for setting up Spring projects quickly

• Microservices support

• Actuator for monitoring and managing applications
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Q2. Java oops concept and sql questions
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Q1. Questions on the current project
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Q2. Microservices architecture in spring microservices
Ans. 
Microservices architecture in Spring is a way of designing software applications as a collection of loosely coupled services.
• Microservices architecture breaks down a large application into smaller, independent services that can be developed, deployed, and scaled independently.

• Spring Boot and Spring Cloud are commonly used frameworks for building microservices in Java.

• Each microservice typically has its own database and...read more
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Q1. Java 8 new features
Ans. 
Java 8 introduced several new features including lambda expressions, streams, and default methods.
• Lambda expressions allow for functional programming and simplify code.

• Streams provide a way to process collections of data in a functional way.

• Default methods allow for adding new methods to interfaces without breaking existing implementations.

• Other new features include the Date and Time API, Nashorn JavaScript engine, and...read more
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Q2. Stream api coding questions
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Q1. Your last project
Ans. 
Developed a web-based inventory management system for a retail company
• Used Java, Spring Boot, and MySQL for backend development

• Implemented a responsive UI using AngularJS and Bootstrap

• Integrated barcode scanning functionality for faster inventory management

• Implemented user authentication and authorization using Spring Security

• Deployed the application on AWS EC2 instance
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Q2. Challenged faced in last project
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Integrated a new payment gateway in the project
• Had to understand the API documentation of the payment gateway

• Had to modify the existing codebase to integrate the new gateway

• Had to test the integration thoroughly to ensure it works as expected
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For freshers there is online aptitude test.

Coding round is done by interviewers on live screen sharing

Q1. Here they discuss about projects and work in depth.
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Q1. Tell me about yourself? What are your hobbies? If you get chance to work with our company what is your expectations from us?
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Q2. Discuss about policies and work culture
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