4000+ Senior Software Engineer Interview Questions and Answers

OAuth authorization is a protocol that allows a user to grant limited access to their resources without sharing their credentials.

• OAuth allows a user to grant access to their resources to a third-party application without sharing their credentials.

• It involves the exchange of tokens between the user, the third-party application, and the resource server.

• OAuth uses authorization codes, access tokens, and refresh tokens to authenticate and authorize access.

• OAuth 2.0 is the curren...read more

I have utilized design patterns such as Singleton, Factory, and Observer in my work.

• Singleton pattern for ensuring a class has only one instance

• Factory pattern for creating objects without specifying the exact class

• Observer pattern for defining a one-to-many dependency between objects

Left join and left outer join are the same thing.

• Both return all records from the left table and matching records from the right table.

• The only difference is in the case of no matching records in the right table.

• Left join returns null values for the right table columns while left outer join returns all columns with null values for non-matching records.

Map transforms each element of a collection, while flatMap transforms each element into a new collection.

• Map applies a function to each element of a collection and returns a new collection with the transformed elements.

• FlatMap applies a function to each element of a collection and returns a new collection by concatenating the resulting collections.

• Map returns a collection with the same number of elements as the original collection, while flatMap can return a collection with a...read more

Automating a web service when client sends requirement

• Analyze the requirement and identify the necessary APIs

• Create test cases and scripts for the APIs

• Use a tool like Postman or SoapUI to automate the testing

• Integrate the automation with a CI/CD pipeline for continuous testing

• Monitor the service for any issues and update the automation as needed

Improving SQL performance involves optimizing queries, indexes, and server resources.

• Optimize queries by reducing complexity and avoiding unnecessary joins

• Use indexes to speed up data retrieval

• Ensure server resources are adequate for the workload

• Consider partitioning large tables to improve query performance

• Use stored procedures to reduce network traffic and improve security

Storage classes in C define the scope and lifetime of variables.

• auto: default storage class for local variables

• register: stores variables in CPU registers for faster access

• static: retains value between function calls

• extern: used to access global variables across multiple files

Check if the black king is under attack and if it is checkmate.

• Check if any white knight can capture the black king

• Check if the black king has any legal moves to escape capture

• If the black king is under attack and has no legal moves, it is checkmate

AWS offers a wide range of cloud services with various key features.

• EC2 - virtual servers in the cloud

• S3 - scalable object storage

• RDS - managed relational databases

• Lambda - serverless computing

• DynamoDB - fully managed NoSQL database

• Elastic Beanstalk - easy deployment and scaling of web applications

A classloader in Java is a part of the Java Runtime Environment that dynamically loads Java classes into the Java Virtual Machine.

• Classloaders are responsible for loading classes during runtime based on the fully qualified name of the class.

• There are different types of classloaders in Java such as Bootstrap Classloader, Extension Classloader, and System Classloader.

• Classloaders follow a delegation model where a classloader delegates the class loading to its parent classloader...read more

I have used both Material UI and Bootstrap for styling.

• I have used Material UI for a project that required a more modern and sleek design.

• I have used Bootstrap for a project that required a more traditional and familiar design.

• Both frameworks have their strengths and weaknesses, and I choose the one that best fits the project's needs.

• I am also familiar with other styling frameworks such as Semantic UI and Foundation.

Handling customized exceptions in controller advice with example code

• Create a custom exception class that extends RuntimeException

• Create a controller advice class to handle exceptions globally

• Use @ExceptionHandler annotation in the controller advice class to handle specific exceptions

• Return a custom error response with appropriate status code and message

The order of output is fs, process, setTimeout, setInterval, promise.

• fs module is synchronous and will output first

• process is next in line

• setTimeout will be executed after process

• setInterval will be executed after setTimeout

• promise will be executed last

Output comparison of for loops using var, let, and bind in JavaScript.

• Using var: variable is function-scoped, may lead to unexpected behavior in loops.

• Using let: variable is block-scoped, recommended for loop iterations.

• Using bind: creates a new function with a specified 'this' value and initial arguments.

I work on coding, debugging, testing, and collaborating with team members. Tech stack decisions are based on project requirements, scalability, performance, and team expertise.

• Daily tasks include coding, debugging, testing, and collaborating with team members

• Tech stack decisions are based on project requirements, scalability, performance, and team expertise

• Consider factors like language compatibility, libraries/frameworks availability, community support, and future scalabilit...read more

The microservices in our current project are designed using a combination of RESTful APIs and event-driven architecture.

• Microservices are designed to be loosely coupled and independently deployable.

• Each microservice focuses on a specific business domain or functionality.

• Communication between microservices is done through RESTful APIs and message queues.

• We use event-driven architecture for handling asynchronous communication and data flow.

• Each microservice is responsible for i...read more

1. To get the last property of an object in JavaScript, you can use Object.keys() method. 2. To count the number of properties in an object, you can use Object.keys() method. 3. To trigger a lambda function with S3, you can use S3 event notifications.

• To get the last property of an object in JavaScript, you can use Object.keys() method and access the last key in the array.

• To count the number of properties in an object, you can use Object.keys() method and get the length of the...read more

Virtual DOM is a lightweight copy of the actual DOM, useState is a hook for managing state in functional components, and Hooks are functions that let you use state and other React features in functional components.

• Virtual DOM is a lightweight copy of the actual DOM that React uses to improve performance by updating only the necessary parts of the actual DOM.

• useState is a hook in React that allows functional components to have state. It returns an array with the current state ...read more

Types of lookups in Datastage include Normal Lookup, Sparse Lookup, and Sparse Join. Lookup failure join conditions include Inner Join, Left Outer Join, Right Outer Join, and Full Outer Join.

• Normal Lookup: Matches input data with reference data and returns matching records.

• Sparse Lookup: Similar to Normal Lookup but does not return any records if no match is found.

• Sparse Join: Combines input data with reference data based on matching conditions.

• Lookup failure join conditions:...read more

List is an ordered collection of elements, while a Dictionary is a collection of key-value pairs.

• List maintains elements in a specific order, while Dictionary stores key-value pairs where keys are unique.

• Accessing elements in a List is done by index, while accessing values in a Dictionary is done by key.

• Example: List - [1, 2, 3], Dictionary - {'a': 1, 'b': 2, 'c': 3}

Realtime state management techniques include WebSockets, Server-Sent Events, and GraphQL Subscriptions.

• WebSockets allow bidirectional communication between client and server, enabling real-time updates.

• Server-Sent Events allow the server to push updates to the client without the client having to request them.

• GraphQL Subscriptions allow clients to subscribe to specific data and receive updates when that data changes.

• Other techniques include polling, long polling, and Comet.

Denormalization is the process of adding redundant data to improve query performance.

• Reduces the number of joins required to retrieve data

• Improves read performance

• Increases data redundancy

• May require additional effort to maintain data consistency

Steps for updating a build and performing rollback

• Create a backup of the current build before making any changes

• Update the build with the necessary changes and test thoroughly

• If issues are found, identify the cause and plan for rollback

• Rollback by restoring the backup of the previous build

• Communicate the rollback to the team and document the process

Yes, I am comfortable writing my own CSS.

• I have experience in writing CSS for various projects.

• I am familiar with CSS preprocessors like Sass and Less.

• I am comfortable using CSS frameworks like Bootstrap and Foundation.

• I am proficient in writing responsive CSS for different screen sizes.

• I am aware of CSS best practices and maintainable code standards.

There are 10 modules in the project that communicate with each other using REST APIs and message queues.

• There are 10 modules in the project

• Communication is done using REST APIs and message queues

• Each module has defined endpoints for communication

Calling stored procedures in code first approach and code first migration

• Use Entity Framework to call stored procedures in code first approach

• Create a DbContext class with DbSet properties for entities and DbSets for stored procedures

• Use the Database.SqlQuery method to execute stored procedures in code first migration

Delegates are a type-safe function pointer used to encapsulate a method.

• Delegates allow methods to be passed as parameters to other methods.

• They can be used to implement callbacks and event handlers.

• Delegates can be chained together to create a pipeline of method calls.

• They are commonly used in .NET framework for event handling and LINQ queries.

Microservices are a software development technique where applications are composed of small, independent services that communicate over well-defined APIs.

• Microservices break down a large application into smaller, loosely coupled services.

• Each microservice is responsible for a specific function and can be developed, deployed, and scaled independently.

• Communication between microservices is typically done through APIs, allowing for flexibility and resilience.

• Microservices archit...read more

Use a loop to iterate through the string and manually split it based on a specified delimiter.

• Create an empty array to store the split strings.

• Iterate through the characters of the string using a loop.

• Check for the delimiter character and split the string accordingly.

• Add the split substrings to the array.

• Return the array of split strings.

Handling exceptions in microservices, config server, ClassNotFoundException vs NoClassDefException

• 1. Exception handling in microservices involves using try-catch blocks to catch and handle exceptions at the service level.

• 2. Config server is a centralized server that stores configuration information for microservices, allowing them to retrieve configurations at runtime.

• 3. ClassNotFoundException occurs when a class is not found at runtime, while NoClassDefFoundError occurs when...read more

Improving Front End System Performance

• Optimize images and reduce their size

• Minimize HTTP requests and use caching

• Use lazy loading for images and videos

• Reduce the number of DOM elements

• Use a Content Delivery Network (CDN)

• Minimize the use of external scripts and plugins

• Use asynchronous loading for scripts

• Optimize CSS and JavaScript files

• Use browser caching

• Implement server-side rendering

On-premises servers can be connected to the Cloud using VPN or Direct Connect.

• Use a VPN to establish a secure connection between on-premises servers and the Cloud.

• Direct Connect can be used for a dedicated, private connection between on-premises servers and the Cloud.

• Ensure proper network configuration and security measures are in place.

• Examples of VPN solutions include OpenVPN, Cisco AnyConnect, and AWS VPN.

• Examples of Direct Connect providers include AWS Direct Connect and ...read more

Inline elements are elements that do not start on a new line and only take up as much width as necessary. Block elements are elements that start on a new line and take up the full width available.

• Inline elements include <span>, <a>, <strong>, <em>, <img>, <input>, <button>

• Block elements include <div>, <p>, <h1> - <h6>, <ul>, <ol>, <li>, <table>, <form>

Java 8 streams are a sequence of elements that support functional-style operations.

• Streams allow for processing collections of data in a declarative way.

• They support operations like filter, map, reduce, and collect.

• Streams can be sequential or parallel, allowing for efficient processing of large datasets.

• Example: List<String> names = Arrays.asList("Alice", "Bob", "Charlie"); Stream<String> stream = names.stream();

Address the issue directly with the peer and offer support and guidance to help improve their performance.

• Have a one-on-one conversation with the peer to discuss their performance and identify any challenges they may be facing.

• Provide constructive feedback and offer resources or training to help them improve.

• Set clear expectations and goals for improvement, and follow up regularly to track progress.

• Offer mentorship or pair programming sessions to help the peer learn and grow....read more

Delegate is a type that represents references to methods with a specific parameter list and return type.

• Delegates are similar to function pointers in C++.

• They are used to achieve loose coupling and separation of concerns.

• There are two types of delegates: singlecast and multicast.

• Singlecast delegates can hold references to a single method.

• Multicast delegates can hold references to multiple methods.

• Delegates are commonly used in event handling and callback scenarios.

Session management, design patterns, OOP concepts, C#, JavaScript, jQuery, LINQ

• Session management types: in-process, out-of-process, database, cookie-based

• Design patterns: Singleton, Factory, Observer, MVC

• OOP concepts: Inheritance, Polymorphism, Encapsulation, Abstraction

• C#: Strongly typed language, supports object-oriented programming

• JavaScript: Dynamic scripting language, used for client-side web development

• jQuery: JavaScript library for simplifying HTML document traversal ...read more

Testing is the process of evaluating a system or application to identify any defects or errors.

• Testing involves executing a system or application to ensure it meets specified requirements.

• Types of testing include unit testing, integration testing, system testing, and acceptance testing.

• Testing helps identify bugs, defects, and issues in software before it is released to users.

• Automated testing tools like Selenium, JUnit, and TestNG are commonly used in industry.

• Testing is ess...read more

The pause feature in Selenium IDE allows users to pause the execution of a test case for a specified amount of time.

• The pause command is used to introduce a delay in the test execution.

• It takes a parameter specifying the time to pause in milliseconds.

• For example, 'pause 3000' will pause the test execution for 3 seconds.

Service is a software component that performs a specific task. Job scheduler and work manager are types of services used in software development.

• A service is a self-contained component that performs a specific task.

• Types of services include web services, microservices, and background services.

• Job scheduler is a service that schedules and executes jobs at specific times or intervals.

• Work manager is a service that manages and prioritizes work requests.

• Job scheduler is time-base...read more

Find duplicates in list and create dictionary with character count in string.

• Iterate through the list and use a dictionary to keep track of character count.

• For each string in the list, iterate through the characters and add them to the dictionary.

• If the character already exists in the dictionary, increment its count.

• If the character does not exist in the dictionary, add it with a count of 1.

• Finally, iterate through the dictionary and print out the characters and their counts.

Finding second largest element in an array without sorting using hash set.

• Create a hash set and iterate through the array, adding each element to the set.

• Initialize two variables to keep track of the largest and second largest elements.

• Iterate through the set and compare each element to the largest and second largest variables.

• Return the second largest variable.

We use a combination of automated and manual deployment processes to ensure code is deployed efficiently and accurately.

• We have a continuous integration and deployment pipeline set up using tools like Jenkins and Ansible.

• We also have a manual deployment process where a designated team member reviews and approves the deployment.

• We use version control systems like Git to manage code changes and ensure that only approved changes are deployed.

• We have a rollback plan in place in c...read more

Inheritance is a mechanism in object-oriented programming where a subclass acquires the properties and behaviors of its parent class.

• Inheritance allows for code reuse and promotes a hierarchical organization of code.

• The child class can override or extend the properties and behaviors inherited from the parent class.

• Inheritance can be single, multiple, or multilevel depending on the number of parent classes involved.

• Example: A class Animal can be a parent class for subclasses l...read more

I have worked on various functional areas and platforms including Java, Python, and AWS.

• I have experience in developing software using Java and Python programming languages.

• I have worked on AWS platform for developing and deploying software applications.

• I have expertise in developing web applications using frameworks like Spring and Django.

• I have experience in working with databases like MySQL and MongoDB.

• I have worked on various software development methodologies like Agile ...read more

Answers to technical questions related to software engineering

• Middleware is software that connects different software applications

• An example of middleware in Express js is body-parser

• To consume API from React with Hooks, use the useEffect hook and fetch API

• Database design should include tables, relationships, and data types

• Service workers in JavaScript allow for offline functionality and caching

Yes, I am currently using VPC in some of my AWS lambda projects.

• I have set up VPC configurations to control access to my Lambda functions

• I have used VPC endpoints to securely access AWS services from my Lambda functions

• I have configured security groups and network ACLs within the VPC for added security