3SD Solutions Java Developer Interview Questions and Answers

Q1. Internal working of HashMap
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Q2. Features of java8
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Q3. Use of synchronized keyword
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Q4. Difference between failsafe and fail fast and also its implementation
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Q5. Coding question : sort an array, use of streams to find names from employee object whose salary is greater than 50000
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Q6. Difference between concurrent and generic collection
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Q7. What is string pool. What is string literal?
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Q8. Security measures used in your project
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Q9. What is difference between rest and soap
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Q10. What do u mean by REST state
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Q11. What is serialization? What is the way to stop serialization?
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Q1. Difference between failsafe and faifast
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Q2. Difference between concurrent and generic collection
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Q3. Security measures used in current project
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Q4. Why you are leaving your current organization and follow up questions on that
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Q1. Java 8 , java 11 and java 17 features?
Ans. 
Java 8 introduced lambda expressions, Java 11 added local-variable syntax for lambda parameters, and Java 17 included sealed classes and pattern matching.
• Java 8 introduced lambda expressions for functional programming.

• Java 11 added local-variable syntax for lambda parameters to simplify code.

• Java 17 included sealed classes to restrict inheritance and pattern matching for instanceof checks and type casts.
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Q2. Dispatcher servlet, design patterns
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Q3. @SpringbootApplication annotation, actuators
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Q4. String Coding question with java 8 features such as lambda function and stream api
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Q5. Number of words in a string
Ans. 
Count the number of words in a given string.
• Split the string by spaces and count the number of resulting elements.

• Handle edge cases like multiple spaces or empty strings.

• Consider punctuation marks as part of words unless specified otherwise.
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Q6. Microservice design patterns
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Q1. Coding questions on java8
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Q2. Regarding microservices
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Q3. Internal working of circuit breaker
Ans. 
Circuit breaker is a design pattern used in software development to prevent system failures by temporarily stopping requests to a failing service.
• Circuit breaker monitors the number of failures and opens when a threshold is reached.

• When the circuit is open, requests are not sent to the failing service, preventing further failures.

• After a specified time, the circuit breaker closes and allows requests to be sent again.

• Ex...read more
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Q4. Frequency of occurrence of words
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Frequency of occurrence of words in a given text can be calculated by counting each word and storing it in a data structure.
• Split the text into words using whitespace as delimiter

• Create a map to store word frequencies

• Iterate through the words and update the frequency count in the map

• Return the map with word frequencies
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Q5. How spring boot will work two databases
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Spring Boot can work with two databases by configuring multiple data sources and using @Primary annotation.
• Configure multiple data sources in application.properties or application.yml

• Use @Primary annotation to specify the primary data source

• Use @Qualifier annotation to specify the secondary data source

• Example: @Configuration @EnableTransactionManagement public class DatabaseConfig { @Primary @Bean(name = "primaryDataSo...read more
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Q1. Difference between hashmap and hash table
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 generally preferred for non-thread-safe applications, while HashTable is used in mul
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Q2. Static block related questions
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Q3. Arraylist and linkedlist question
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Onlin test consist pf easy numerical questions

Easy questions not so difficult

Q1. Java oops concept
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Q2. Basic sprophramming questions
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Q3. Networking firewall cisco
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Q1. Personal questions
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Q2. Whetehr to willing to work in any locations
Ans. 
Yes, I am willing to work in any location for the right opportunity.
• I am open to relocating for the right job opportunity

• I am flexible and adaptable to new environments

• I believe working in different locations can provide valuable experiences and growth opportunities
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Q1. Spring boot architechture
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Q2. Streams coding questions
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Q3. Second highest salary sql
Ans. 
To find the second highest salary in SQL, use the 'SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);'
• Use the MAX() function to find the highest salary in the table

• Use a subquery to find the maximum salary that is less than the highest salary

• Combine both queries to get the second highest salary
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Q4. Solid priciples
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Q5. Acid properties
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ACID properties are a set of properties that guarantee database transactions are processed reliably.
• ACID stands for Atomicity, Consistency, Isolation, Durability

• Atomicity ensures that all operations in a transaction are completed successfully or none at all

• Consistency ensures that the database remains in a consistent state before and after the transaction

• Isolation ensures that transactions are executed independently of...read more
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First round is quit easy

2 coding question based on dsa

Q1. Explain different phases of sdlc
Ans. 
SDLC stands for Software Development Life Cycle, which consists of different phases from planning to maintenance.
• 1. Planning phase involves defining project scope, requirements, and creating a project plan.

• 2. Analysis phase focuses on gathering and analyzing requirements to create a detailed system design.

• 3. Design phase involves creating a high-level design, detailed design, and architecture for the software.

• 4. Implem...read more
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Q2. 4 paillers of datastructure.
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The 4 pillars of data structure are arrays, linked lists, stacks, and queues.
• Arrays: Data structure that stores a collection of elements with a fixed size.

• Linked Lists: Data structure where each element points to the next element in the sequence.

• Stacks: Data structure that follows the Last In First Out (LIFO) principle.

• Queues: Data structure that follows the First In First Out (FIFO) principle.
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Q1. Core Java, multithreading and foncurrency
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Q2. Springboot , app
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Q3. Working of hashset

Ans. 

HashSet is a collection that does not allow duplicate elements and does not guarantee the order of elements.

• HashSet uses a hash table for storage.

• Elements are stored based on their hash code.

• Adding an element to a HashSet returns false if the element is already present.

• Example: HashSet set = new HashSet<>(); set.add("apple");

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