Atlassian SDE-2 Interview Questions and Answers

Round duration - 45 minutes
Round difficulty - Medium

Technical Interview round that lasted for about 45 minutes. Questions were based on Java, Java design Patterns and OOPS Concepts.

Q1. What are static methods in interfaces?
Ans. 
Static methods in interfaces are methods that can be called without creating an instance of the interface implementation.
• Static methods in interfaces were introduced in Java 8.

• They are used for providing utility methods that are related to the interface but do not require an instance of the implementing class.

• Static methods in interfaces cannot be overridden by implementing classes.

• Example: interface MyInterface { stat...read more
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Q2. Why was a new version of Java (Java 8) needed in the first place?
Ans. 
Java 8 was needed to introduce new features like lambda expressions, streams, and default methods.
• Introduction of lambda expressions for functional programming

• Streams API for processing collections in a functional style

• Default methods in interfaces for backward compatibility

• Improved performance with the introduction of the Nashorn JavaScript engine

• Date and Time API for better handling of date and time operations
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Q3. In how many ways can you create a singleton pattern in Java?
Ans. 
There are multiple ways to create a singleton pattern in Java, including using static initialization, lazy initialization, and enum.
• Using static initialization: Create a private static instance of the class and a public static method to return that instance.

• Lazy initialization: Create a private static instance of the class and a public static method to check if the instance is null before creating it.

• Using enum: Create...read more
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Round duration - 60 minutes
Round difficulty - Medium

Technical Interview round that lasted for about 45 minutes. Questions were based on Spring boot and Microservices Concepts.

Q1. What is the difference between the Bridge Pattern and the Adapter Pattern in Java?
Ans. 
Bridge Pattern decouples abstraction from implementation, while Adapter Pattern adapts an interface to another.
• Bridge Pattern separates abstraction and implementation using composition, while Adapter Pattern adapts an interface to another without changing its original structure.

• Bridge Pattern allows for changes in both abstraction and implementation independently, while Adapter Pattern allows incompatible interfaces to...read more
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Q2. What is the difference between @RestController and @Controller in Spring Boot?
Ans. 
Difference between @RestController and @Controller in Spring Boot
• 1. @Controller is used to create web MVC controllers while @RestController is used to create RESTful web services.

• 2. @Controller returns the view to be rendered while @RestController returns the object and data is written directly to the HTTP response as JSON or XML.

• 3. @RestController is a specialized version of @Controller that includes @Controller and @...read more
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Q3. What is the difference between Spring and Spring Boot?
Ans. 
Spring is a framework for building Java applications, while Spring Boot is an extension that simplifies the setup and configuration.
• Spring is a comprehensive framework for building Java applications, providing features like dependency injection, aspect-oriented programming, and more.

• Spring Boot is an extension of the Spring framework that aims to simplify the setup and configuration of Spring applications.

• Spring Boot i...read more
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Q4. What is the difference between Monolithic and Microservices Architecture?
Ans. 
Monolithic architecture is a single-tiered software application where all components are tightly coupled, while microservices architecture is a distributed approach where the application is broken down into smaller, loosely coupled services.
• Monolithic architecture has a single codebase and database, while microservices have multiple smaller services with their own codebase and database.

• Monolithic applications are harde...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions

Q1. Why should we hire you?
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Round duration - 60 minutes
Round difficulty - Easy

Q1. 
Make Palindrome Problem Statement
You are provided with a string STR of length N comprising lowercase English alphabet letters. Your task is to determine and return the minimum number of characters that n...read more
Ans. 
The task is to determine the minimum number of characters needed at the beginning of a string to make it a palindrome.
• Iterate from both ends of the string and compare characters to find the number of characters needed to make it a palindrome.

• Use dynamic programming to optimize the solution by storing results of subproblems.

• Handle edge cases like an already palindrome string or an empty string.

• Example: For 'deed', no ch...read more
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Q2. 
Wildcard Pattern Matching Problem Statement
Implement a wildcard pattern matching algorithm to determine if a given wildcard pattern matches a text string completely.
The wildcard pattern may include the...read more
Ans. 
Implement a wildcard pattern matching algorithm to determine if a given wildcard pattern matches a text string completely.
• Create a dynamic programming matrix to store intermediate results

• Handle cases for '?' and '*' characters separately

• Check if the characters in the pattern and text match accordingly

• Return 'True' if the text matches the pattern, otherwise 'False'
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Round duration - 90 minutes
Round difficulty - Medium

It was nice

Q1. What is BCNF and why is it important in database management systems?
Ans. 
BCNF stands for Boyce-Codd Normal Form, a higher level of normalization in database management systems.
• BCNF is a stricter form of 3NF (Third Normal Form) and ensures that there are no non-trivial functional dependencies between attributes.

• It helps in reducing redundancy and anomalies in the database.

• BCNF is important as it helps in maintaining data integrity and improving database performance.

• Example: If we have a tabl...read more
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Q2. You are given a rectangular container filled with 1 liter of liquid. How can you pour out half a liter without seeing or measuring it?
Ans. 
Tilt the container until the liquid reaches the edge, then pour out half of it.
• Tilt the container slowly until the liquid reaches the edge

• Once the liquid is at the edge, pour out half of it

• This method works because the liquid will naturally settle at the lowest point, allowing you to estimate the halfway mark
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Round duration - 45 mintues
Round difficulty - Easy

Very nice interviews very helpful.

Round duration - 360 minutes
Round difficulty - Hard

Timing- Any 6 hours of my choice in the 24 hour window. (10:00 p.m. to 4:00 a.m. I selected)
Environment was very friendly and easy to use.
No significant activity.
This was the only coding round.

Q1. 
Prime Time Again Problem Statement
You are given two integers DAY_HOURS and PARTS. The integer 'DAY_HOURS' represents the number of hours in a day, and the day can be divided into 'PARTS' equal parts. You...read more
Ans. 
Find total instances of equivalent prime groups in a day divided into equal parts.
• Iterate through each part of the day and check for prime pairs in different parts

• Use a helper function to check if a number is prime

• Ensure the day is evenly divided by parts and each prime group has hours from different parts
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Round duration - 10-15 minutes
Round difficulty - Easy

Timing- 12:15 p.m. 
Environment was very good .
Not any significant activity.
The interviewer was very friendly and talked like friends.

Round duration - 20 minutes
Round difficulty - Medium

Timing- 12:30 p.m. to 12:45 p.m
Environment was very comfortable.
No other significant activity.
Interviewer was very good and talking very politely & friendly.

Round duration - 30 minutes
Round difficulty - Medium

It was in the morning about 10:00AM-10:40AM. The platform used for this round was hackerrank. There are 15 MCQ's which cover portions of Aptitude, Data Structures, DBMS, SQL

Q1. 
Minimum Operations Problem Statement
You are given an array 'ARR' of size 'N' consisting of positive integers. Your task is to determine the minimum number of operations required to make all elements in t...read more
Ans. 
Minimum number of operations to make all elements in the array equal by performing addition, subtraction, multiplication, or division.
• Iterate through the array to find the maximum and minimum values.

• Calculate the difference between the maximum and minimum values.

• The minimum number of operations needed is the difference between the maximum and minimum values.
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Round duration - 15 minutes
Round difficulty - Easy

It was in the night around 7:00PM-7:20PM. Platform used for this round was skype. Interviewer was very serious while taking my interview.

Round duration - 180 minutes
Round difficulty - Hard

Timing: 8 a.m. to 11a.m.
Environment was optimum.
No significant activity.

Q1. 
Edit Distance Problem Statement
Given two strings S and T with lengths N and M respectively, your task is to find the "Edit Distance" between these strings.
The Edit Distance is defined as the minimum nu...read more
Ans. 
The task is to find the minimum number of operations required to convert one string into another using delete, replace, and insert operations.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the minimum edit distance for substrings of the two input strings.

• Iterate through the strings and update the array based on the operations needed for each character.

• Return the value in the bottom ...read more
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Round duration - 30 minutes
Round difficulty - Medium

Timing: 12:00 p.m. to 12:30 p.m.
The environment was quite good.
No significant activity.
Interviewers were very friendly. They were behaving like friends.

Round duration - 15 minutes
Round difficulty - Easy

Timing: 3:00 p.m. to 3:20 p.m.
Environment was very good.
No significant activity was monitored.
HR was very good and friendly.