Jar Backend Developer Intern Interview Questions and Answers

Q1. Mostly on projects and previous tech knowledge
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Q2. Whats the difference between == and .equal()?
Ans. 
The difference between == and .equal() is that == is used to compare values for equality, while .equal() is a method used to compare objects for equality.
• The == operator is used to compare primitive data types like integers, strings, etc. for equality.

• The .equal() method is used to compare objects in Java for equality. It is typically overridden in classes to define custom equality logic.

• Example: int a = 5; int b = 5; ...read more
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Q3. What happens a primitive data type is passed in a method call and non-primitive data types are passes? when would there be change in value after downstream operation and opposite
Ans. 
Primitive data types are passed by value, while non-primitive data types are passed by reference. Changes in value can occur after downstream operations for non-primitive data types.
• Primitive data types (int, float, char, etc.) are passed by value, meaning a copy of the value is passed to the method. Changes made to the parameter inside the method do not affect the original value.

• Non-primitive data types (objects, arra...read more
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Q4. What are the common annotations used in spring boot
Ans. 
Common annotations used in Spring Boot for backend development
• 1. @RestController - used to define a controller and to indicate that the return value of the methods should be directly written to the HTTP response body

• 2. @RequestMapping - used to map web requests to specific handler methods

• 3. @Autowired - used for automatic dependency injection

• 4. @Service - used to indicate that a class is a service

• 5. @Repository - used ...read more
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Q5. Questions on get and post method
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Q6. Modified question on Trapping the rain water
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Q1. Basic HR type questions again, projects, tech
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Q2. Question on java 8 features and above, sql and no sql experience
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Q3. Reverse a string
Ans. 
Reverse a string by iterating through the characters and swapping them
• Create an empty string to store the reversed string

• Iterate through the characters of the input string from end to start

• Append each character to the empty string to reverse the string
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Q4. Stream API, advantages and uses
Ans. 
Stream API is a powerful tool in Java for processing collections of objects.
• Advantages include concise code, improved performance, and ease of parallel processing.

• Uses include filtering, mapping, sorting, and reducing data in collections.

• Example: stream.filter(x -> x > 5).map(x -> x * 2).collect(Collectors.toList());
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Dynamic Programming, Graph

Q1. Projects, SQL, DBMS, OOPS, Javascript
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Q1. Speak confidently
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1 DSA question. Variation of valid anagrams question. There were no test cases against which you had to execute your code. We had to run the code ourselves and make sure that all the edge cases are covered.

Q1. Everything in my resume
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Q2. Is Javascript multithreaded or single threaded
Ans. 
Javascript is single threaded.
• Javascript is single threaded, meaning it can only execute one piece of code at a time.

• This is because of the event loop in Javascript, which manages the execution of code.

• Asynchronous operations in Javascript, like setTimeout or AJAX requests, are handled by the event loop.

• Web Workers can be used to achieve multithreading in Javascript for CPU-intensive tasks.
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Q3. DB Schema of one of my project
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The DB schema of my project includes tables for users, products, orders, and reviews.
• Users table with columns for user ID, username, email, password

• Products table with columns for product ID, name, price, description

• Orders table with columns for order ID, user ID, product ID, quantity

• Reviews table with columns for review ID, product ID, user ID, rating, comment
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Q1. What is your dream role?
Ans. 
My dream role is to work as a lead backend developer in a dynamic tech company, where I can innovate, collaborate with talented individuals, and make a significant impact.
• Lead backend developer in a dynamic tech company

• Opportunity to innovate and collaborate with talented individuals

• Make a significant impact through my work
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Q2. Are you open to working in product roles?
Ans. 
Yes, I am open to working in product roles as it will provide me with a broader perspective and help me understand the end-to-end process.
• I believe working in product roles will enhance my understanding of user needs and market trends.

• It will also allow me to collaborate with cross-functional teams and contribute to the overall product strategy.

• For example, I can work closely with product managers to prioritize feature...read more
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