Future Focus Infotech Java Technical Lead Interview Questions and Answers

Q1. What are java 8 new features
Ans. 
Java 8 introduced lambda expressions, streams, default methods, and more.
• Lambda expressions for functional programming

• Streams for efficient processing of large data sets

• Default methods to add new functionality to existing interfaces

• Date and Time API for improved handling of date and time

• Optional class to avoid null pointer exceptions

• Nashorn JavaScript engine for improved performance

• Parallel array sorting for faster sor
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Q2. What is the difference between stream and parallel stream
Ans. 
Stream is sequential while parallel stream is concurrent
• Stream is a sequence of elements that can be processed sequentially

• Parallel stream is a sequence of elements that can be processed concurrently

• Parallel stream can improve performance for large datasets

• Parallel stream uses multiple threads to process elements in parallel

• Stream is suitable for small datasets or when order of processing is important
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It's walkin, so they conducted 1 technical mcqs round.

Q1. Multi threading
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Q2. Internal working of hashmap
Ans. 
HashMap in Java is a data structure that stores key-value pairs and uses hashing to efficiently retrieve values based on keys.
• HashMap uses an array of buckets to store key-value pairs.

• Keys are hashed to determine the index in the array where the key-value pair will be stored.

• In case of hash collisions, a linked list or a balanced tree is used to store multiple key-value pairs in the same bucket.

• HashMap allows null keys...read more
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Q3. Spring batch related
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Q4. Non repeating characters in a array
Ans. 
Function to find and return all non-repeating characters in an array of strings.
• Iterate through the array and count the occurrences of each character using a HashMap.

• Then iterate through the array again and check if the count of each character is 1, if so add it to the result list.

• Return the list of non-repeating characters.
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Q5. 3rd highest salary
Ans. 
To find the 3rd highest salary in a database, we can use a SQL query with the 'LIMIT' and 'OFFSET' keywords.
• Use a SQL query with 'ORDER BY salary DESC' to sort the salaries in descending order.

• Use 'LIMIT 1 OFFSET 2' to skip the first two highest salaries and retrieve the third highest salary.

• Example: SELECT salary FROM employees ORDER BY salary DESC LIMIT 1 OFFSET 2;
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Q6. Qualifier vs primary
Ans. 
A qualifier in Java is used to specify additional information about a primary, which is the main data type or variable.
• A primary in Java is the main data type or variable, while a qualifier provides additional information about the primary.

• Qualifiers can be used to modify the behavior or characteristics of a primary.

• For example, in Java, 'final' is a qualifier that can be used to make a variable constant.
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Q7. Controller vs restcontroller
Ans. 
The main difference is that @RestController is a specialized version of @Controller that is used for RESTful web services.
• Both @Controller and @RestController are used in Spring MVC to handle HTTP requests, but @RestController is specifically used for RESTful web services.

• @Controller is used to create web pages, while @RestController is used to return data in JSON or XML format.

• @RestController is a convenience annotati...read more
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Q8. Spring boot annotataions
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Q9. Oops concepts with examples
Ans. 
OOP concepts include inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class. Example: class Dog extends Animal.

• Encapsulation: Bundling data and methods that operate on the data into a single unit. Example: private variables with public getter and setter methods.

• Polymorphism: Ability for objects to be treated as instances of their paren...read more
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Q10. Spring batch configuration
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Q11. They covered all java, spring and Microservices
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Q1. Microservices architecture
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Q2. How do Microservices communicate
Ans. 
Microservices communicate with each other through various communication protocols like HTTP, messaging queues, and gRPC.
• Microservices can communicate over HTTP using RESTful APIs.

• Messaging queues like RabbitMQ or Kafka can be used for asynchronous communication between microservices.

• gRPC is a high-performance, open-source RPC framework that can be used for communication between microservices.

• Service discovery mechanism...read more
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Q3. How to access the Microservice end point
Ans. 
Microservice endpoints can be accessed using HTTP requests with the appropriate URL
• Use HTTP methods like GET, POST, PUT, DELETE to interact with the microservice

• Construct the URL with the base URL of the microservice and the specific endpoint path

• Include any necessary headers or parameters in the request for authentication or data filtering
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Q4. Why we use microservices
Ans. 
Microservices allow for modular, scalable, and flexible software development by breaking down applications into smaller, independent services.
• Microservices enable easier maintenance and updates as each service can be developed, deployed, and scaled independently.

• They improve fault isolation, as failures in one service do not necessarily affect the entire application.

• Microservices promote agility and faster time-to-mark...read more
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Q1. Difference between Hashset and Treeset
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Q2. Final Finally and finalize difference
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Q1. Spring Security Implementation
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Q2. Api design Implementation
Ans. 
API design implementation involves creating a well-structured and user-friendly interface for interacting with software applications.
• Understand the requirements and use cases for the API

• Design clear and consistent endpoints with proper documentation

• Implement secure authentication and authorization mechanisms

• Follow RESTful principles for creating APIs

• Consider scalability and performance optimizations
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Q3. Stream API coding question
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Q1. Basic java and API
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Q1. Normal Question
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Q1. I have added the questions below
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Q2. I have added thebelow
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Q1. Based on the resume
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Q1. Scenario based questions
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Q1. Package discussion
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Q1. Explain OOPs concepts.
Ans. 
OOPs concepts are fundamental principles of object-oriented programming that help in designing and implementing software solutions.
• Encapsulation: Bundling data and methods together in a class.

• Inheritance: Creating new classes by inheriting properties and behaviors from existing classes.

• Polymorphism: Ability of an object to take on many forms.

• Abstraction: Hiding complex implementation details and providing a simplified ...read more
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Q2. Write a program to count occurance the letter in a string.
Ans. 
This program counts the occurrence of each letter in a given string.
• Use a HashMap to store the count of each letter.

• Iterate through the characters of the string and update the count in the HashMap.

• Finally, print the count of each letter.
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Q3. Write a SQL query to find third highest salary from employee table.
Ans. 
SQL query to find third highest salary from employee table.
• Use the ORDER BY clause to sort the salaries in descending order

• Use the LIMIT clause to limit the result to the third row

• Use a subquery to exclude the highest and second highest salaries
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Q4. Difference between Array and arraylist.
Ans. 
Array is a fixed-size data structure while ArrayList is a dynamic-size data structure in Java.
• Array has a fixed length, while ArrayList can grow dynamically.

• Array can store both primitive types and objects, while ArrayList can only store objects.

• Array uses square brackets [] for declaration, while ArrayList uses angle brackets <>.

• Array provides direct access to elements using index, while ArrayList provides methods for...read more
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Q5. Explain working of Arraylist.
Ans. 
ArrayList is a dynamic array that can grow or shrink in size. It stores objects and provides methods for adding, removing, and accessing elements.
• ArrayList is part of the Java Collections Framework.

• It is implemented as a resizable array.

• Elements can be added using the add() method.

• Elements can be accessed using the get() method.

• Elements can be removed using the remove() method.

• The size() method returns the number of el...read more
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Q6. What is the default size of an arraylist.
Ans. 
The default size of an ArrayList is 10.
• The default initial capacity of an ArrayList is 10.

• If the number of elements exceeds the initial capacity, the ArrayList automatically increases its size.

• The capacity of an ArrayList can be increased manually using the ensureCapacity() method.
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Q7. Some questions from my resume about my previous experience.
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Q8. The interviewer was stupid and in my opinion they are just wasting your precious time. After the interview they don't provide any updates about the interview.
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