Virinchi Technologies Junior Java Developer Interview Questions and Answers

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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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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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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Q1. == operation & .equals() method method overloading
Ans. 
The == operator is used to compare references in Java, while the .equals() method is used to compare values. Method overloading is when multiple methods have the same name but different parameters.
• Use == to compare references, use .equals() to compare values

• Method overloading allows multiple methods with the same name but different parameters

• Example: String str1 = new String("hello"); String str2 = new String("hello");...read more
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Q2. Linked list working with example
Ans. 
A linked list is a data structure where each element points to the next element in the list.
• Linked list is made up of nodes, each containing data and a reference to the next node.

• Insertion and deletion are efficient in linked lists compared to arrays.

• Example: Node 1 -> Node 2 -> Node 3 -> null
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One coding question with 40-45 mcq

Q1. 2 coding questions from array
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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.
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Q1. Core java questions, springboot, one string coding question
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Q1. Hierarchy of collection framework,
Ans. 
Collection framework in Java provides a hierarchy of interfaces and classes to store and manipulate groups of objects.
• Interfaces: Collection, List, Set, Queue, Map

• Classes: ArrayList, LinkedList, HashSet, TreeSet, HashMap, TreeMap

• Collections class provides utility methods for working with collections
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Q2. Questions on Spring boot, microservices
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