300+ Obbserv Online Services Interview Questions and Answers

The task is to find the Nth prime number given a number N.

• A prime number is a number greater than 1 that is not a product of two smaller natural numbers.

• Prime numbers have only two factors - 1 and the number itself.

• Start with a counter at 0 and a number at 2.

• Increment the number by 1 and check if it is prime.

• If it is prime, increment the counter.

• Repeat until the counter reaches N.

• Return the last prime number found.

The question is about designing and implementing a data structure for LRU cache to support get and put operations.

• LRU cache is a cache replacement policy that removes the least recently used item when the cache reaches its capacity.

• The cache is initialized with a capacity and supports get(key) and put(key, value) operations.

• For each get operation, return the value of the key if it exists in the cache, otherwise return -1.

• For each put operation, insert the value in the cache i...read more

String is immutable, StringBuffer is synchronized and mutable, StringBuilder is mutable and not synchronized.

• String is a sequence of characters and cannot be changed once created.

• StringBuffer is similar to String but mutable and thread-safe.

• StringBuilder is similar to StringBuffer but not thread-safe, making it faster in single-threaded scenarios.

The start() method is used to start a new thread and execute the run() method.

• The start() method creates a new thread and calls the run() method.

• The run() method contains the code that will be executed in the new thread.

• Calling the run() method directly will not create a new thread.

• The start() method should be called to start the execution of the new thread.

Process to find root cause of slow application for database, backend api and frontend side.

• Check server logs for errors and warnings

• Use profiling tools to identify bottlenecks

• Optimize database queries and indexes

• Minimize network requests and optimize API responses

• Reduce image and file sizes for faster loading

• Use caching to reduce server load

• Check for memory leaks and optimize memory usage

Technical interview questions for Software Engineer III position

• Garbage collection in C# is an automatic memory management process

• Dispose and Finalize are methods used to release resources

• Managed resources are objects that are managed by the .NET runtime, while unmanaged resources are external resources that are not managed by the runtime

• CLR (Common Language Runtime) is the virtual machine component of .NET, CLS (Common Language Specification) is a set of rules that language ...read more

Garbage collector in Java is responsible for automatic memory management.

• Garbage collector automatically reclaims memory by freeing objects that are no longer referenced.

• It runs in the background and identifies unused objects based on reachability.

• Different garbage collection algorithms like Mark and Sweep, Copying, and Generational are used.

• Garbage collector can be tuned using JVM options like -Xmx and -Xms.

• Example: System.gc() can be used to suggest garbage collection, but ...read more

Exception handling is a mechanism in programming to handle and manage errors or exceptional situations that may occur during program execution.

• Exception handling is used to catch and handle errors or exceptions in a program.

• It allows the program to gracefully handle errors and prevent abrupt termination.

• Exception handling involves the use of try-catch blocks to catch and handle exceptions.

• The catch block contains code to handle the exception, such as displaying an error messa...read more

HashSet is an unordered collection that uses hashing to store elements, while TreeSet is a sorted collection that uses a binary search tree.

• HashSet does not maintain any order of elements, while TreeSet maintains elements in sorted order.

• HashSet allows null values, while TreeSet does not allow null values.

• HashSet has constant time complexity for basic operations like add, remove, and contains, while TreeSet has logarithmic time complexity.

• HashSet is generally faster for addin...read more

Thread Scheduler is responsible for managing the execution of multiple threads in a multitasking environment.

• Thread Scheduler determines the order in which threads are executed.

• It allocates CPU time to each thread based on priority and scheduling algorithm.

• Time Slicing is a technique used by Thread Scheduler to allocate a fixed time slice to each thread before switching to another.

• It ensures fair execution of threads and prevents a single thread from monopolizing the CPU.

• Exam...read more

The final keyword is used to restrict the modification of variables, methods, and classes.

• Final variables cannot be reassigned once initialized

• Final methods cannot be overridden in subclasses

• Final classes cannot be extended by other classes

Thread starvation occurs when a thread is unable to access the CPU resources it needs to execute its tasks.

• Thread starvation happens when a thread is constantly waiting for a resource that is being monopolized by other threads.

• It can occur due to poor resource management or priority scheduling.

• Examples include a low-priority thread being constantly preempted by high-priority threads or a thread waiting indefinitely for a lock held by another thread.

Abstract class is a class that cannot be instantiated and can have both abstract and non-abstract methods. Interface is a blueprint for a class and can only have abstract methods.

• Abstract class can have constructors while interface cannot.

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

• Abstract class can have instance variables while interface cannot.

• Abstract class can provide default implementations for some methods while interface cannot.

• Int...read more

BlockingQueue is a thread-safe queue that blocks when it is full or empty.

• BlockingQueue is part of the Java Concurrency API.

• It provides methods like put() and take() to add and remove elements from the queue.

• When the queue is full, put() blocks until space becomes available.

• When the queue is empty, take() blocks until an element is available.

• It is commonly used in producer-consumer scenarios.

SDLC and STLC, list vs tuple, assert vs verify

• SDLC (Software Development Life Cycle) is a process followed to develop software

• STLC (Software Testing Life Cycle) is a process followed to test software

• List and tuple are both data structures in Python, but list is mutable while tuple is immutable

• Assert is used to check if a condition is true, while verify is used to check if a web element is present

• Both assert and verify are used in automated testing

• Example: assert 2+2 == 4, ver...read more

To manage multiple insertions of the same file in S3, use versioning and object locking.

• Enable versioning on the S3 bucket to keep track of changes to the file.

• Use object locking to prevent multiple insertions of the same file at the same time.

• Implement a notification system to alert users when a file has been updated.

• Consider using a unique identifier for each file to avoid confusion.

• Implement a backup and recovery plan in case of accidental deletion or corruption.

Possible reasons for an unreachable URL

• Server is down

• Incorrect URL

• DNS resolution failure

• Firewall or security settings

• Network connectivity issues

Calculate average salary of employees over 30 for each designation.

• Filter employees with age > 30

• Group employees by designation

• Calculate average salary for each group

Using stream API to find the sum of even numbers from an ArrayList

• Convert the ArrayList to a stream using the stream() method

• Filter the stream to keep only the even numbers using the filter() method

• Use the mapToInt() method to convert the stream of even numbers to an IntStream

• Finally, use the sum() method to calculate the sum of the even numbers

Design phase is crucial in software development to plan and visualize the system architecture and functionality.

• Identify the requirements and constraints

• Create a high-level design and break it down into smaller components

• Choose appropriate technologies and tools

• Consider scalability, maintainability, and security

• Iterate and refine the design based on feedback

• Examples: UML diagrams, flowcharts, wireframes

To make a singleton class thread safe, use synchronized keyword or double-checked locking. Volatile keyword ensures visibility of changes across threads.

• Use synchronized keyword to ensure only one thread can access the instance at a time

• Use double-checked locking to avoid unnecessary synchronization

• Declare the instance variable as volatile to ensure visibility of changes across threads

• Example: public static synchronized Singleton getInstance() { if (instance == null) { instan...read more

RestController is used for RESTful web services while Controller is used for general web requests.

• RestController is a specialization of Controller annotation in Spring framework.

• RestController is used to create RESTful web services that return JSON or XML data.

• Controller is used for handling general web requests and returning views (HTML).

• RestController is typically used for APIs while Controller is used for traditional web applications.

ConcurrentHashMap is a thread-safe implementation of Map interface in Java.

• ConcurrentHashMap allows multiple threads to read and write concurrently without blocking each other.

• It internally divides the map into segments and locks each segment separately to allow concurrent access.

• Other synchronized structures like Hashtable and synchronizedMap lock the entire map, causing performance issues.

• ConcurrentHashMap is preferred over synchronized structures in high-concurrency scenar...read more

Questions related to Java concepts and frameworks

• Fail safe fail fast - used in concurrent programming to handle exceptions and ensure thread safety

• String is immutable to ensure thread safety and prevent unintended changes to the string

• String buffer vs String builder - both are used to manipulate strings, but string builder is faster and not thread-safe

• Executor framework - used for asynchronous task execution and thread pooling

• Lombok Transient Volatile Synchronized keyword Fin...read more

I stands for Interface Segregation Principle in SOLID design principles.

• Interface Segregation Principle states that a client should not be forced to depend on methods it does not use.

• It promotes the use of smaller, cohesive interfaces instead of large, monolithic ones.

• This helps in reducing the coupling between different components of the system.

• For example, if a class needs only a subset of methods from an interface, it should not be forced to implement all the methods.

• Inste...read more

Overlay is a network virtualization technique that adds a layer of abstraction over the physical network, while underlay refers to the physical network infrastructure.

• Overlay is used to create virtual networks on top of the physical network infrastructure.

• Underlay refers to the physical network infrastructure that provides connectivity between devices.

• Overlay networks are used to provide network virtualization, multi-tenancy, and network segmentation.

• Underlay networks are res...read more

To access rest endpoint in asynchronous manner, use AJAX or fetch API with async/await or promises.

• Use AJAX or fetch API to make asynchronous requests to the REST endpoint

• Use async/await or promises to handle the asynchronous response

• Ensure that the endpoint supports asynchronous requests

I am currently using Visual Studio Code as my primary tool for software development.

• Visual Studio Code is a lightweight and versatile code editor.

• It has a wide range of extensions and plugins available for customization.

• It supports multiple programming languages and has built-in Git integration.

• Other tools I have experience with include Eclipse, IntelliJ IDEA, and Sublime Text.

Smoke test is a subset of sanity test. Smoke test checks if the critical functionalities are working. Sanity test checks if the major functionalities are working.

• Smoke test is performed to ensure that the critical functionalities of the software are working as expected.

• Sanity test is performed to ensure that the major functionalities of the software are working as expected.

• Smoke test is a subset of sanity test.

• Smoke test is a quick and shallow test to identify major issues ea...read more

Prepared Statements interface is used to prevent SQL injection.

• Prepared Statements interface is used to parameterize the SQL queries.

• It allows the separation of SQL code and user input.

• It helps to prevent SQL injection attacks by automatically escaping special characters.

• Examples: PDO, mysqli, Java PreparedStatement, etc.

Test cases should be written based on scenarios or requirements to ensure thorough testing coverage.

• Understand the scenario or requirement thoroughly before writing test cases

• Identify different test scenarios based on the given scenario or requirement

• Write test cases that cover positive, negative, and edge cases

• Include preconditions and expected outcomes in each test case

• Ensure test cases are clear, concise, and easy to understand

• Review and validate test cases with stakeholde...read more

Bug is a defect in software, error is a mistake made by a programmer, black box testing is testing without knowledge of internal code.

• Bug: a flaw in software that causes it to behave unexpectedly or incorrectly

• Error: a mistake made by a programmer that results in incorrect code

• Black box testing: testing without knowledge of the internal code, focusing on inputs and outputs

• Example: entering invalid data into a form and receiving an error message

• Example: a button on a website n...read more

NoSql is sufficient when data is unstructured and requires high scalability and performance.

• Consider the type of data and its structure

• Evaluate the scalability and performance requirements

• Assess the need for complex queries and transactions

• Examples: social media data, IoT data, real-time analytics

Immutable class with List/Date Type property

• Create a final class with private final fields

• Use unmodifiableList() to create immutable List

• Use defensive copying for Date property

• No setters, only getters

• Override equals() and hashCode() methods

Java interview questions on array manipulation, threading, and string immutability.

• To find min and max in an array, initialize min and max variables to the first element and iterate through the array comparing each element to update min and max accordingly.

• To reverse an array, swap the first and last elements, then the second and second-to-last elements, and so on until the middle of the array is reached.

• Java threads allow for concurrent execution of code. Use the Thread clas...read more

To make a db entity unmodifiable, use constraints or triggers to prevent updates or deletes.

• Use a constraint to prevent updates or deletes on the entity

• Create a trigger to roll back any update or delete operation on the entity

• Grant read-only access to the entity to prevent modifications

• Use database permissions to restrict modification access to the entity

• Consider using a separate read-only database for the entity

Collaboration tools can help in software development by improving communication, increasing productivity, and facilitating project management.

• Collaboration tools like Slack, Trello, and Jira can improve communication between team members and stakeholders.

• Version control systems like Git can help manage code changes and facilitate collaboration among developers.

• Project management tools like Asana and Basecamp can help teams stay organized and on track.

• Code review tools like Gi...read more

Use JCL to extract 5th row from a PS file

• Use the SORT utility in JCL to extract the 5th row from the PS file

• Specify the starting position and length of the record in the SORT statement

• Use the OUTFIL statement to write the extracted row to an output file

Swift is a modern programming language while Objective-C is an older language used for iOS development.

• Swift is easier to read and write than Objective-C.

• Swift is faster than Objective-C.

• Objective-C is still used in legacy codebases.

• Swift has a simpler syntax and is more concise.

• Swift has better memory management than Objective-C.

The application uses OAuth 2.0 for authentication and role-based access control for authorisation.

• OAuth 2.0 is an industry-standard protocol for authorisation and authentication.

• Role-based access control restricts access based on the user's role.

• Examples of roles include admin, user, and guest.

• OAuth 2.0 allows users to grant access to their resources without sharing their credentials.

• The application may also use multi-factor authentication for added security.

Working for Adobe is exciting due to their innovative culture, cutting-edge technology, and global impact.

• Innovative culture fosters creativity and encourages experimentation

• Cutting-edge technology provides opportunities to work with the latest tools and techniques

• Global impact means that work has a wide-reaching influence and can make a difference in the world

• Opportunities for growth and development through training and mentorship programs

• Collaborative and inclusive work env...read more

Relational database is a type of database that stores and organizes data in tables with relationships between them.

• Data is stored in tables with rows and columns

• Tables can have relationships with each other through keys

• SQL is commonly used to query and manipulate data in relational databases

• Examples include MySQL, PostgreSQL, Oracle

Use SQL query to compare two tables and fetch records based on condition

• Use JOIN clause to compare two tables

• Add a WHERE clause to specify the condition for fetching records

• Select the desired columns from the tables

Automate the probability of rolling a dice and getting 4-6 each time for 10 rolls.

• Use a loop to simulate rolling the dice 10 times

• Generate a random number between 1 and 6 to represent the dice roll

• Check if the number is 4, 5, or 6 for each roll

• Calculate the overall probability of getting 4-6 on each roll

A user story is a concise description of a feature told from the perspective of the end user.

• A user story typically follows the format: As a [type of user], I want [some goal] so that [some reason].

• User stories help capture the 'who', 'what', and 'why' of a feature in a simple and understandable way.

• Components of a user story include a title, narrative, acceptance criteria, and priority.

• Example: As a customer, I want to be able to track my order status so that I can know when...read more

Annotations are used to provide metadata about classes, methods, or fields in an API.

• Annotations can be used to provide information about how a method should be handled, such as whether it is deprecated or should be ignored by a compiler.

• Annotations can also be used to provide information about how a class should be serialized or deserialized, such as specifying the format of JSON data.

• Examples of annotations include @Deprecated, @Override, @JsonProperty, and @JsonIgnore.

Schematics are diagrams that show the components and connections of a system or device.

• Schematics are visual representations of circuits or systems

• They show the components used and how they are connected

• Commonly used in electronics and engineering fields

Count the number of set bits in a given number.

• Use bitwise AND operator with 1 to check if the rightmost bit is set.

• Shift the number to right by 1 bit and repeat the process until the number becomes 0.

• Keep a count of the number of set bits encountered.

• Example: For number 5 (101 in binary), the answer is 2 as there are 2 set bits.

• Example: For number 15 (1111 in binary), the answer is 4 as there are 4 set bits.

Stream, Lambda and Functional interface can be combined to write functional programming in Java

• Streams provide a functional way to process collections of data

• Lambda expressions allow for functional programming by providing a way to pass behavior as an argument

• Functional interfaces define the contract for a lambda expression

• Example: using a stream to filter a list of integers and then using a lambda expression to map each integer to its square

Answering questions related to current project architecture, designing scalable micro services, ensuring CI/CD, OAuth, and authorization servers.

• Current project architecture involves a detailed analysis of the existing system, identifying key components, and designing a scalable solution.

• Designing micro services to be scalable requires breaking down the application into smaller, independent services that can be easily deployed and managed.

• Ensuring CI/CD works as expected invo...read more

I will build a product tailored to the unique needs and challenges faced by retailers in semi urban markets.

• Conduct market research to understand the specific requirements and preferences of retailers in semi urban areas

• Develop a user-friendly and cost-effective solution that addresses key pain points such as inventory management, supply chain logistics, and customer engagement

• Provide training and support to ensure successful adoption and implementation of the product

• Collabor...read more

Object-oriented programming is a programming paradigm based on the concept of objects, which can contain data and code.

• Objects are instances of classes, which define the structure and behavior of the objects.

• Encapsulation, inheritance, and polymorphism are key principles of object-oriented programming.

• Example: In a banking application, a 'Customer' class can have attributes like name and account balance, and methods like deposit and withdraw.

Boot loader is a program that loads the operating system into the computer's memory during startup.

• Boot loader is the first software program that runs when a computer starts.

• It is responsible for loading the operating system kernel into memory.

• Boot loaders can be specific to the hardware architecture of the computer.

• Examples of boot loaders include GRUB for Linux systems and NTLDR for Windows systems.

Types of communication include verbal, non-verbal, written, and visual communication.

• Verbal communication: involves speaking and listening, such as conversations and phone calls.

• Non-verbal communication: includes body language, gestures, and facial expressions.

• Written communication: involves written words, such as emails, reports, and letters.

• Visual communication: includes graphs, charts, and presentations to convey information visually.

Java 16 and Spring Boot 2.5 are the latest versions with new features and improvements.

• Java 16 introduces Records, Pattern Matching for instanceof, and Vector API among others.

• Spring Boot 2.5 includes support for Java 16, improved startup time, and better error messages.

• Other new features in Spring Boot 2.5 include support for Kotlin 1.5, Micrometer 1.7, and Spring Data 2021.0.

In SSIS, you can manage different sets of columns in two files by using conditional splits and dynamic column mapping.

• Use a conditional split transformation to separate the data flow based on the file type or column presence

• Create separate data flows for each file type and handle the columns accordingly

• Use dynamic column mapping to map the columns dynamically based on the file type

• You can use expressions and variables to dynamically handle the column mapping

• Handle any additio...read more