Bluestream Software Solution Java Software Developer Interview Questions and Answers

Q1. What is OOP Concepts
Ans. 
OOP Concepts refer to the principles of Object-Oriented Programming, including encapsulation, inheritance, and polymorphism.
• Encapsulation: Bundling data and methods that operate on the data into a single unit (object)

• Inheritance: Allowing a new class to inherit properties and behavior from an existing class

• Polymorphism: The ability for objects of different classes to respond to the same message in different ways
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Q2. What is Method Overloading and Method Overriding
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Method overloading is when multiple methods have the same name but different parameters. Method overriding is when a subclass provides a specific implementation of a method that is already provided by its parent class.
• Method overloading involves creating multiple methods in the same class with the same name but different parameters.

• Method overriding occurs in a subclass that provides a specific implementation of a meth...read more
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Q3. Servlet Life Cycle
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Q4. Spring boot annotations
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Q5. What you know about Multithreading
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Multithreading is a programming concept where multiple threads run concurrently within a single process.
• Allows for parallel execution of tasks

• Improves performance by utilizing multiple CPU cores

• Requires synchronization to prevent race conditions

• Examples: creating a GUI application with responsive UI, processing multiple requests simultaneously in a web server
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Q6. What are design patterns you follow in microservices architecture
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Some design patterns in microservices architecture include Service Registry, Circuit Breaker, and API Gateway.
• Service Registry: Allows services to dynamically discover and communicate with each other.

• Circuit Breaker: Prevents cascading failures by failing fast and providing fallback mechanisms.

• API Gateway: Acts as a single entry point for clients to access multiple microservices.

• Event Sourcing: Stores the state of a sy...read more
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Q7. What is JDK Vs JIT
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JDK is Java Development Kit, which includes tools for developing Java applications. JIT is Just-In-Time compiler, which compiles Java bytecode to native machine code at runtime.
• JDK is a software development kit used for developing Java applications.

• JIT is a component of the Java Virtual Machine (JVM) that improves the performance of Java applications by compiling bytecode to native machine code at runtime.

• JDK includes ...read more
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Q1. Basic Java Question
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Q2. Spring Boot related questions
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Q1. Design a rest API and code it.
Ans. 
Design and code a REST API for a software developer interview.
• Define the endpoints and HTTP methods for the API (e.g. GET /users, POST /users)

• Implement authentication and authorization mechanisms (e.g. JWT tokens)

• Use proper status codes for responses (e.g. 200 OK, 401 Unauthorized)

• Include error handling and validation for input data

• Document the API using tools like Swagger or OpenAPI
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Q2. Questions related to JPA HIBERNATE SQL
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Q1. Discussion related to Last company Project and architecture level questions
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Q2. Write code to calculate frequency of a word using Stream API and lambda expressions
Ans. 
Calculate word frequency using Stream API and lambda expressions
• Use Stream API to convert array of strings to stream

• Use Collectors.groupingBy to group words by their frequency

• Use Collectors.counting to count the occurrences of each word
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Q1. How annotation works?
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Annotations in Java provide metadata about a program that can be used by the compiler or at runtime.
• Annotations start with the @ symbol.

• Annotations can be used to provide information to the compiler or to runtime environments.

• Annotations can be used to define custom metadata for classes, methods, fields, etc.

• Annotations can also be used for code generation, documentation, and validation.

• Examples of annotations in Java ...read more
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Q2. CondurentSkipListMap, how does it work
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ConcurrentSkipListMap is a concurrent, sorted map implementation in Java.
• ConcurrentSkipListMap is a concurrent version of SkipListMap, which is a sorted map implementation based on skip list data structure.

• It allows multiple threads to access and modify the map concurrently.

• It provides logarithmic time complexity for most operations, making it efficient for concurrent access.

• Example: ConcurrentSkipListMap
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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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DSA questions and programming concepts

Q1. Reverse string and optimize it
Ans. 
Reverse array of strings efficiently
• Use two pointers approach to swap characters from start and end of each string

• Optimize by using in-place reversal instead of creating new strings

• Consider edge cases like empty strings or strings with only one character
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Q2. Reverse binary tree
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Q1. Salary expectations
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Q2. Joining location
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Q1. What is Concrete class ?
Ans. 
A concrete class is a class that can be instantiated, meaning it can be used to create objects.
• Cannot be abstract

• Can be instantiated

• Can have concrete methods and properties

• Example: class Car {}
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Q1. OS questions,graph dfs question, geeks for geeks chocolate factory question
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Q1. Children sum property trees,height of BT
Ans. 
The question is about implementing a children sum property in trees and finding the height of a binary tree.
• Children sum property in trees means that the value of a node must be equal to the sum of the values of its children nodes.

• To find the height of a binary tree, you can recursively calculate the height of the left and right subtrees and return the maximum height plus one.

• Example: For a binary tree with nodes 1, 2,
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