BNY Senior Backend Developer Interview Questions and Answers

Q1. Difference between query and path param in spring boot
Ans. 
Query param is used to pass parameters in the URL query string, while path param is used to define parameters in the URL path itself.
• Query param is specified after the '?' in the URL, like '?param=value'

• Path param is specified in the URL path itself, like '/{param}'

• Query params are optional and can be used for filtering or sorting data

• Path params are used to define variables in the URL path, like IDs or names
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Q2. Difference between array and array list
Ans. 
Arrays have fixed size, while ArrayLists can dynamically resize. ArrayLists are part of Java Collections framework.
• Arrays have a fixed size, while ArrayLists can dynamically resize.

• Arrays can hold primitive data types and objects, while ArrayLists can only hold objects.

• Arrays use square brackets [] for declaration, while ArrayLists use angle brackets <>.

• Arrays are faster than ArrayLists for accessing elements directly ...read more
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Q3. Difference between abstract and interface
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, fields, and methods, while interface cannot have any of these.

• A class can extend only one abstract class, but can implement multiple interfaces.

• Abstract classes are used to provide a common base for subclasses, while interfaces are used to define a contract for classes to ...read more
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Q1. System design of iot machine
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Designing a system for IoT machines involves creating a network that allows devices to communicate and share data.
• Consider the communication protocols needed for devices to connect and exchange data

• Implement security measures to protect data and prevent unauthorized access

• Design a scalable architecture to handle a large number of devices and data

• Utilize cloud services for storage and processing of IoT data

• Include edge ...read more
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Linked list implementation

A hackerrank test was shared which had 2 ques to be solved in 60 min in Node.JS. The first one was a simple DS question related to arrays. The second ques was to write routes and controllers for a Node.JS Express app. The routes were GET /projects, GET /project/:id and GET /projects/active

Q1. What is the difference between package and package-lock.json?
Ans. 
package.json lists dependencies and package-lock.json ensures consistent installs.
• package.json lists all the dependencies required for the project

• package-lock.json ensures that the same versions of dependencies are installed across all environments

• package.json is manually edited while package-lock.json is generated automatically

• package-lock.json is used for reproducible builds
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Q2. Write a function that can keep a count of certain functions in our application.
Ans. 
Function to count certain functions in the application
• Create a dictionary to store the count of each function

• Increment the count of the function each time it is called

• Include a reset function to reset the count of all functions

• Example: def count_functions(): function_count = {}

• Example: def function1(): function_count['function1'] += 1

• Example: def reset_count(): function_count.clear()
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Q3. How can we make sure that package versions are taken from package-lock.json and not package.json
Ans. 
To ensure package versions are taken from package-lock.json, use npm ci instead of npm install.
• npm ci installs packages based on package-lock.json

• npm install may update package versions in package.json

• Always commit package-lock.json to version control
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Q4. Create an object and write a function inside it.
Ans. 
Creating an object with a function inside it.
• Create an object using object literal notation

• Define a function inside the object using function expression or declaration

• Access the function using object.method() syntax
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Q5. Given an array that has stock prices from morning till afternoon. Return the best buy and sell price to gain the max profit. For example, input -> [2,5,8,1,3,6,9,3,6], output -> [1,9]
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We all do our own work but what if someone needs your help after working hours, will you be able to help or neglect?

Come up with the new ideas while working on the old ones, explain that how you can introduce them gradually in the team and what are the benefits of doing so.