Visa Interview Questions, Process, and Tips

Round duration - 45 minutes
Round difficulty - Easy

This was a technical interview round.

Q1. How does AJAX work?
Ans. 
AJAX allows web pages to be updated asynchronously by exchanging data with a web server behind the scenes.
• AJAX stands for Asynchronous JavaScript and XML.

• It allows web pages to update content without reloading the entire page.

• AJAX uses XMLHttpRequest object to send and receive data from a server.

• Commonly used in web applications to provide a more responsive user experience.
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Q2. What is the difference between SOAP and REST?
Ans. 
SOAP is a protocol, while REST is an architectural style for web services.
• SOAP is a protocol that uses XML for message format and relies on a request-response model.

• REST is an architectural style that uses standard HTTP methods like GET, POST, PUT, DELETE.

• SOAP is more rigid and requires more bandwidth, while REST is lightweight and flexible.

• SOAP has built-in security features like WS-Security, while REST relies on exte...read more
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Q3. What is the difference between GET and POST methods in APIs?
Ans. 
GET is used to request data from a server, while POST is used to submit data to a server.
• GET requests data from a specified resource, while POST submits data to be processed to a specified resource.

• GET requests are cached by browsers, while POST requests are not.

• GET requests can be bookmarked and shared, while POST requests cannot.

• GET requests have length restrictions, while POST requests do not.

• Example: Using GET to r...read more
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Q4. What is the Observer Pattern?
Ans. 
The Observer Pattern is a behavioral design pattern where an object (subject) maintains a list of dependents (observers) that are notified of any state changes.
• Allows for one-to-many dependency between objects

• When the subject's state changes, all observers are automatically notified and updated

• Commonly used in event handling systems and GUI frameworks
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Round duration - 40 minutes
Round difficulty - Easy

This was the second technical interview round.

Q1. What is a singleton class?
Ans. 
A singleton class is a class that can only have one instance created throughout the entire application.
• Singleton classes have a private constructor to prevent multiple instances from being created.

• They typically provide a static method to access the single instance.

• Commonly used for logging, database connections, and configuration settings.
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Q2. What is meant by immutability in Java?
Ans. 
Immutability in Java refers to the property of objects whose state cannot be changed once they are created.
• Immutability ensures that once an object is created, its state cannot be modified.

• Immutable objects are thread-safe and can be shared without the risk of data corruption.

• String class in Java is an example of an immutable class.

• To create an immutable class, make the class final, all fields private, and provide only
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Q3. What is dependency injection?
Ans. 
Dependency injection is a design pattern where components are given their dependencies rather than creating them internally.
• Allows for easier testing by providing mock dependencies

• Promotes loose coupling between components

• Improves code reusability and maintainability

• Examples: Constructor injection, Setter injection, Interface injection
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Q4. How do you create an immutable class in Java?
Ans. 
To create an immutable class in Java, make the class final, make all fields private and final, provide only getter methods, and do not provide any setter methods.
• Make the class final to prevent inheritance.

• Make all fields private and final to prevent modification.

• Provide only getter methods to access the fields.

• Do not provide any setter methods to modify the fields.
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.

Round duration - 60 minutes
Round difficulty - Easy

Technical Interview round with questions on DSA.

Q1. 
Stock Buy and Sell Problem Statement
You are given an array of integers PRICES where PRICES[i] represents the price of a stock on the i-th day, and an integer K representing the number of transactions you...read more
Ans. 
Determine maximum profit with at most K transactions by buying and selling stocks on given days.
• Iterate through the array of prices while keeping track of the maximum profit achievable with at most K transactions.

• Use dynamic programming to store the maximum profit at each day and transaction count.

• Consider buying and selling stocks at each day to calculate the maximum profit.

• Return the maximum profit achievable with at
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Q2. 
Sorted Order Printing of a BST Array
Given a Binary Tree consisting of 'N' nodes with integer values, your task is to determine the in-order traversal of the Binary Tree.
Input:
The first line contains ...read more
Ans. 
The task is to determine the in-order traversal of a Binary Tree given in level order.
• Implement a function to perform in-order traversal of a Binary Tree

• Use recursion to traverse left subtree, visit root, and then traverse right subtree

• Handle null nodes denoted by -1 in the input
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.