Velocis Systems Java Developer Interview Questions and Answers

Q1. Given an array of non-negative integers.Find the length of the longest subsequence such that elements in the subsequence are contiguous integers. The consecutive numbers can be in any order. Example n=7 nu...read more
Ans. 
Find the length of the longest subsequence of contiguous integers in an array.
• Sort the array

• Iterate through the array and check for consecutive integers

• Keep track of the longest subsequence found
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Q2. Get list of pincodes from these objects Employee{ id Long, name String, Addresses : List
} Addresses{ houseNo long, pindcode long, state String, country String, } Ans. Use flatMap to flatten and then use m...read more
Ans. 
Use flatMap and map to extract list of pincodes from Employee objects
• Use flatMap to flatten the list of Addresses in each Employee object

• Use map to iterate over the flattened list and extract the pincodes

• Example: employeeList.stream().flatMap(emp -> emp.getAddresses().stream()).map(address -> address.getPincode()).collect(Collectors.toList())
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Q3. What is Database Pooling, Hikari and its configurations. Java 8 to current enchancements and current java version Factory and Builder design patterns to explain and code Project expalantion and details, Cr...read more
Ans. 
Database pooling is a technique used to manage a pool of database connections for efficient resource utilization. HikariCP is a popular database connection pooling library in Java.
• HikariCP is a high-performance database connection pooling library for Java applications.

• It is known for its low latency and high throughput.

• Configurations for HikariCP include settings such as maximum pool size, connection timeout, and idle ...read more
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Q1. Explain Spring Boot
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Q2. What is Redux in React
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Q3. What is Context API in React
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Q1. Difference between Hashset and Treeset
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Q2. Final Finally and finalize difference
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Simple logical based

Palindrome
Reverse a string

Q1. Oops pillar define and explain
Ans. 
The four pillars of Object-Oriented Programming (OOP) are Abstraction, Encapsulation, Inheritance, and Polymorphism.
• Abstraction: Hides complex implementation details and only shows the necessary features to the outside world.

• Encapsulation: Bundles data and methods that operate on the data into a single unit, preventing direct access to data from outside the class.

• Inheritance: Allows a new class to inherit properties an...read more
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20 aptitude,20 comunication,4 program questions

General topics . topics about online class vs office line class

Q1. In this round also they mainly check communication.after that basic questions about the what you put on your resume
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Q1. General round. In this round they told about the company and bond
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This test was conducted in MSG browser and it has around 30 questions and around 3 to 5 are related to coding

Our topic of discussion is future of jobs and take the first initiative and don't go off topic and try to agree and add points with the fellow members

Q1. Tell me about yourself
Ans. 
Experienced Java Developer with a passion for creating efficient and scalable solutions.
• Over 5 years of experience in Java development

• Strong knowledge of object-oriented programming principles

• Proficient in Spring framework and Hibernate

• Experience with RESTful web services and microservices architecture

• Familiar with Agile development methodologies
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Q2. Tell me about the project
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Q3. Do you known nodejs
Ans. 
Yes, Node.js is a JavaScript runtime built on Chrome's V8 JavaScript engine.
• Node.js is used for server-side scripting and building scalable network applications.

• It allows developers to use JavaScript for both client-side and server-side development.

• Node.js has a large ecosystem of open-source libraries and frameworks like Express.js.

• It is commonly used for building real-time web applications, APIs, and microservices.
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Q1. Difference between ArrayList and LinkedList?
Ans. 
ArrayList is implemented as a resizable array, while LinkedList is implemented as a doubly linked list.
• ArrayList provides fast random access, LinkedList provides fast insertion and deletion.

• ArrayList uses more memory as it needs to allocate a fixed size array, LinkedList uses more memory for storing references to the next and previous elements.

• Example: ArrayList is better for scenarios where random access is required, ...read more
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Q2. Difference between HashMap and HashTable?
Ans. 
HashMap is non-synchronized and allows null values, while HashTable is synchronized and does not allow null values.
• HashMap is non-synchronized, meaning it is not thread-safe, while HashTable is synchronized and thread-safe.

• HashMap allows null values for both keys and values, while HashTable does not allow null keys or values.

• HashMap is faster than HashTable as it is non-synchronized, but HashTable is preferred in multi...read more
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Q1. Micro service disadvantage
Ans. 
Microservices can introduce complexity, communication overhead, and potential performance issues.
• Increased complexity due to managing multiple services

• Communication overhead between services

• Potential performance issues due to network latency

• Difficulty in maintaining consistency across services
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Q2. @functionalinterface can we extend or not, map & flatmap
Ans. 
No, @FunctionalInterface cannot be extended. Map and flatMap are default methods in the interface and cannot be overridden.
• No, @FunctionalInterface cannot be extended as it is a single abstract method interface.

• Map and flatMap are default methods in the interface and cannot be overridden.

• Example: public interface MyInterface { void myMethod(); default void myDefaultMethod() { // implementation } }
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