CentraLogic Node JS Developer Interview Questions and Answers

Q1. Stringbuilder and string buffer diff
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Q2. Where we store the object of string
Ans. 
Objects of String are stored in the String Pool in Java.
• String objects are stored in the String Pool, a special memory area in Java heap memory.

• String literals are automatically stored in the String Pool.

• String objects created using the new keyword are not stored in the String Pool.

• String.intern() method can be used to store a String object in the String Pool.
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Q3. What is bean in springboot
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A bean in Spring Boot is a Java object that is instantiated, assembled, and managed by the Spring IoC container.
• Beans are defined in the Spring configuration file or using annotations like @Component, @Service, @Repository, etc.

• Beans are singleton by default but can be scoped as prototype, request, session, etc.

• Beans are injected into other beans using dependency injection.

• Example: @Component annotation is used to defi
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Q4. What is query parameters and path param
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Query parameters are used to pass data to a web server through the URL, while path parameters are part of the URL itself.
• Query parameters are key-value pairs added to the end of a URL after a '?'

• Path parameters are variables within the URL path itself, denoted by curly braces {}

• Example of query parameter: www.example.com/api/users?id=123

• Example of path parameter: www.example.com/api/users/{userId}
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Q5. Code snippet related to exception
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Q6. Diff between exception and error
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Exceptions are recoverable errors that can be handled in code, while errors are unrecoverable issues that usually result in program termination.
• Exceptions are checked at compile time, while errors are unchecked.

• Exceptions are subclasses of Throwable, while errors are subclasses of Error.

• Examples of exceptions include FileNotFoundException, NullPointerException, while examples of errors include OutOfMemoryError, StackOv
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Q1. Functional interface
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Q2. Find if array of numbers, which are prime, using streams
Ans. 
Use streams to find prime numbers in an array
• Use Java streams to filter out non-prime numbers from the array

• Check if a number is prime by dividing it by all numbers less than its square root

• Create a method to check if a number is prime
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DP graphs strings it was good

Q1. Reverse a linkded list
Ans. 
Reverse a linked list by changing the direction of pointers
• Start with three pointers: current, previous, and next

• Iterate through the list, updating pointers to reverse the direction

• Return the new head of the reversed list
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Q2. Print fibonacci series
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The Fibonacci series is a sequence of numbers where each number is the sum of the two preceding ones.
• Start with two variables initialized to 0 and 1

• Loop through desired number of iterations, adding the previous two numbers to get the next number

• Print or store each number in the series
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Q1. Java, lambda expressions, micro services
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Q1. Microservices architecture, saga pattern
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Q1. Managerial, how do you improve your skills etc
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Q1. Dependency injection
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Q2. What are oops concepts
Ans. 
Object-oriented programming concepts that focus on data encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: bundling data and methods that operate on the data into a single unit (class)

• Inheritance: ability of a class to inherit properties and behavior from another class

• Polymorphism: ability to present the same interface for different data types

• Abstraction: hiding the complex implementation details
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Q1. Why do you want to switch
Ans. 
I want to switch to explore new technologies and challenges in a different industry.
• Interested in learning new skills and technologies

• Seeking new challenges and opportunities for growth

• Want to explore different industry perspectives
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Q2. Salry expectations
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Q1. Question on oop concepts
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Q2. Coding questions
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Q1. Ask to write code for equal and hashcode in notepad
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Q2. Type of Collections and its internal working
Ans. 
Java collections are data structures that store and manipulate groups of objects.
• Types of collections include List, Set, Map, Queue, etc.

• Internal workings involve data structures like arrays, linked lists, hash tables, etc.

• Collections framework provides interfaces and classes for working with collections.
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Q3. Count number of occurrence of string from Array
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Count occurrences of a specific string in an array of strings.
• Iterate through the array and use a HashMap to store the count of each string.

• Use the string as key and increment the count each time it is encountered.

• Return the count of the specific string at the end.
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Q4. Write a code using stream
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Using stream to filter a list of strings
• Use the filter method to apply a predicate to each element in the stream

• Convert the stream back to a list using the collect method
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Api based questions where to post or get fetch data

Q1. Dp questions were asked
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Q2. Sql basic questions were asked
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