People Tech Group Junior Java Developer Interview Questions and Answers

Aptitude test like technical questions

Coding test for technical analysis

Q1. HR is asking same basic questions java
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Q1. Technical questions asked
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Q2. Full stack java developer
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There were 3 to 4 questions related to the camera that needed to be solved within the given time.

Q1. Postmortem of Hashmap
Ans. 
Hashmap postmortem involves analyzing performance, memory usage, collisions, and resizing.
• Analyze performance: Check for time complexity of operations like get, put, and remove.

• Memory usage: Evaluate memory footprint and potential memory leaks.

• Collisions: Investigate collision resolution strategies like separate chaining or open addressing.

• Resizing: Examine load factor and rehashing process for efficient resizing.

• Examp...read more
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Q2. Locking mechanism in multithreading
Ans. 
Locking mechanism in multithreading is used to control access to shared resources by multiple threads.
• Locks are used to prevent multiple threads from accessing shared resources simultaneously

• Types of locks include synchronized blocks, ReentrantLock, and ReadWriteLock

• Locks help prevent race conditions and ensure data consistency in multithreaded applications
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Q3. Find highest salaried emp from each dept
Ans. 
Use SQL query to group by department and find employee with highest salary in each department
• Write a SQL query to group by department and select max salary for each department

• Join the result with employee table to get employee details

• Example: SELECT dept, emp_name, MAX(salary) FROM employees GROUP BY dept
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Q4. Sorting algorithms
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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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It was medium level java coding questions along with springboot, mcqs

Q1. ArrayList vs LinkedList
Ans. 
ArrayList is better for random access and LinkedList is better for frequent insertions and deletions.
• ArrayList uses dynamic array to store elements, allowing fast random access but slower insertions and deletions.

• LinkedList uses doubly linked list to store elements, allowing fast insertions and deletions but slower random access.

• Example: Use ArrayList when you need to frequently access elements by index. Use LinkedList...read more
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Q2. HashMap working
Ans. 
HashMap is a data structure in Java that stores key-value pairs and allows fast retrieval of values based on keys.
• HashMap is part of the Java Collections framework.

• It allows null keys and values.

• HashMap does not maintain insertion order.

• Example: HashMap map = new HashMap<>();
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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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Q1. They asked some core Java Concepts,String,Java 8,SpringBoot Architecture,Stream API code
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1 Assignment which you need to solve in front of the interviewer

Q1. Questions on Java Streams
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Q2. Questions on springboot
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