600+ Senior Software Developer Interview Questions and Answers

Yes, a unique key can also be a primary key.

• A primary key must be unique, but a unique key does not necessarily have to be the primary key.

• A table can have multiple unique keys, but only one primary key.

• Example: In a table of employees, the employee ID can be a unique key and also the primary key.

Django is a web framework for building full-stack applications, while Django Rest is an extension for building RESTful APIs.

• Django is a full-stack web framework that includes features for building web applications with a user interface.

• Django Rest is an extension of Django that provides tools for building RESTful APIs.

• Filter queries in Django allow you to retrieve specific data from the database based on certain conditions.

• Foreign keys in Django are used to establish relation...read more

ConcurrentHashMap in Java is a thread-safe version of HashMap, allowing multiple threads to access and modify the map concurrently.

• ConcurrentHashMap achieves thread-safety by dividing the map into segments, each guarded by a separate lock.

• It allows multiple threads to read and write to the map concurrently, without blocking each other.

• It provides better performance than synchronized HashMap for concurrent operations.

• Example: ConcurrentHashMap<String, Integer> map = new Concur...read more

Abstract classes are used when we want to provide a default implementation and interfaces are used when we want to enforce a contract.

• Abstract classes can have both abstract and non-abstract methods while interfaces can only have abstract methods.

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

• Abstract classes can have constructors while interfaces cannot.

• Interfaces are used for achieving multiple inheritance in Java.

• An example of an abs...read more

Joins are used to combine data from two or more tables based on a related column between them.

• Use JOIN keyword followed by the name of the table to join

• Specify the columns to be selected using SELECT keyword

• Use ON keyword to specify the related column between tables

• Types of joins: INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id

useState is used for managing simple state in functional components, while useReducer is used for more complex state logic.

• useState is a basic hook for managing state in functional components

• useReducer is more suitable for managing complex state logic and actions

• useState is simpler and easier to use for basic state management

• useReducer allows for more control and flexibility in managing state changes

• useState is typically used for independent pieces of state, while useReducer ...read more

Microservices are a software architecture pattern where applications are broken down into small, independent services.

• Microservices can be scaled up or down by adding or removing instances of the service as needed.

• Docker is a containerization platform that allows for easy deployment and management of microservices.

• Microservices communicate with each other through APIs or message queues.

• Scaling microservices requires careful consideration of the service's dependencies and reso...read more

Escalation matrix defines the process for escalating production defects based on severity and impact.

• Escalation matrix typically includes levels of escalation, responsible parties at each level, and criteria for escalating defects.

• For example, a Level 1 escalation may involve the development team, while a Level 2 escalation may involve senior management.

• Criteria for escalation may include severity of the defect, impact on users or business operations, and potential solutions....read more

Yes, it is okay to give deliverables under pressure as long as quality is not compromised.

• Meeting deadlines is important in software development.

• Pressure can sometimes lead to increased focus and productivity.

• Communication with stakeholders about realistic timelines is key.

• Prioritizing tasks and managing time effectively can help in delivering under pressure.

The yield() method in threading is used to give up the CPU and allow other threads to run.

• Allows other threads to run by giving up the CPU temporarily

• Useful for preventing one thread from dominating the CPU

• Can be used to implement cooperative multitasking

Segregate an array of 0s and 1s with minimum swaps.

• Count the number of 0s in the array.

• Swap the 1s with the 0s until all 0s are on one side and 1s on the other.

• The minimum number of swaps required is half the number of 1s on the side with fewer 1s.

Use copy() function to create a new slice and reflect changes in original slice to the new slice.

• Use the copy() function to create a new slice with the same length as the original slice.

• Make changes to the original slice.

• The changes made to the original slice will automatically reflect in the new slice as well.

Use a loop to follow redirects until reaching a 200 status code and print all URLs.

• Start with the initial URL and make a request to it.

• Check the status code of the response, if it's 200 then print the URL.

• If the status code is a redirect (300-399), follow the redirect URL and repeat the process.

• Continue this process until a 200 status code is received.

Microservices are small, independent services that work together to form a larger application.

• Microservices allow for greater flexibility and scalability in software development.

• Each microservice can be developed, deployed, and scaled independently.

• Microservices communicate with each other through APIs.

• Examples of companies using microservices include Netflix, Amazon, and Uber.

finalize() is a method in Java used for cleanup operations before an object is garbage collected, while dispose() is a method used for releasing unmanaged resources in .NET.

• finalize() is a method in Java that is called by the garbage collector before an object is reclaimed. It is used for cleanup operations like closing files or releasing resources.

• dispose() is a method in .NET that is used for releasing unmanaged resources like file handles or database connections. It is typ...read more

There are three types of controllers in MVC: 1. View Controller 2. Action Controller 3. Partial View Controller

• View Controller handles user interface and displays data

• Action Controller handles user input and performs actions

• Partial View Controller handles reusable UI components

• Examples: HomeController, AccountController, ProductController

Routing in MVC is the process of mapping URLs to controller actions.

• Routing is defined in the RouteConfig.cs file in ASP.NET MVC applications.

• Routes are defined using the MapRoute method, which specifies the URL pattern and the controller and action to handle the request.

• Routes are matched in the order they are defined, with the first match being used to handle the request.

• Route parameters can be defined in the URL pattern and passed to the controller action as method paramet...read more

Remotely access client machine, analyze issue, troubleshoot, and provide solution

• Request remote access to client machine

• Analyze reported issue thoroughly

• Troubleshoot the problem step by step

• Communicate with client for additional information

• Provide a detailed solution and ensure it resolves the issue

Utilize AWS or Azure services for scalable web applications

• Use AWS Elastic Beanstalk or Azure App Service for easy deployment and scaling

• Leverage AWS Lambda or Azure Functions for serverless computing

• Utilize AWS Auto Scaling or Azure Autoscale to automatically adjust resources based on traffic

• Store data in AWS RDS or Azure SQL Database for scalable database solutions

• Use AWS CloudFront or Azure CDN for content delivery and faster load times

Yes, I have worked on Telecom domain in my previous role.

• I have experience developing software solutions for telecom companies to improve network performance and customer experience.

• I have worked on projects involving billing systems, network management, and customer relationship management.

• I have knowledge of telecom protocols such as SIP, VoIP, and SS7.

• I have collaborated with telecom engineers to integrate software solutions with telecom infrastructure.

Use authentication, authorization, encryption, input validation, and monitoring to ensure API security in .NET.

• Implement authentication mechanisms like OAuth or JWT to verify the identity of clients accessing the API.

• Use authorization to control access to different parts of the API based on user roles and permissions.

• Encrypt sensitive data transmitted over the API using protocols like HTTPS.

• Validate and sanitize input data to prevent injection attacks like SQL injection or cr...read more

Code reviews, automated testing, continuous integration, coding standards, and documentation.

• Conduct regular code reviews to catch errors and ensure adherence to best practices.

• Implement automated testing to verify code functionality and catch bugs early.

• Utilize continuous integration to regularly merge code changes and run automated tests.

• Enforce coding standards to maintain consistency and readability.

• Document code to explain its purpose, functionality, and usage.

Advantages of using a microservice architecture include scalability, flexibility, fault isolation, and technology diversity.

• Scalability: Microservices allow for individual components to be scaled independently, leading to better resource utilization.

• Flexibility: Each microservice can be developed, deployed, and updated independently, allowing for faster innovation and reduced time to market.

• Fault Isolation: If one microservice fails, it does not bring down the entire system, ...read more

CQRS is a design pattern that separates the read and write operations of a system, using different models for each.

• CQRS separates the responsibility of handling commands (write operations) from queries (read operations).

• It helps in achieving better scalability, performance, and maintainability by using different models for reads and writes.

• For example, in a banking application, the write model may handle transactions and account updates, while the read model may handle querie...read more

Cluster load balancing in Node.js helps distribute incoming requests among multiple instances of the application to improve performance and reliability.

• Cluster load balancing allows Node.js applications to utilize multiple CPU cores efficiently by creating child processes to handle incoming requests.

• It helps prevent a single instance of the application from becoming overwhelmed with requests, leading to improved performance and reliability.

• Examples of cluster load balancing t...read more

Yes, I am willing to work on weekends once in 6 weeks.

• I understand the importance of meeting project deadlines and am willing to put in extra effort when necessary.

• I have previous experience working on weekends and understand the need for occasional weekend work in the software development industry.

• I am committed to delivering high-quality work and am willing to make sacrifices to ensure project success.

• I believe in maintaining a healthy work-life balance and will ensure that...read more

Setting up environment in Angular app, understanding pipes, async, pure/impure, Subject and BehaviorSubject in theory

• Setting up environment in Angular app involves configuring environment files for different environments like development, production, etc.

• Pipes in Angular are used for transforming data in templates. Async pipes are used for handling asynchronous data streams.

• Pure pipes are stateless and only recompute when the input values change, while impure pipes can be cal...read more

Django signals are a way for decoupled applications to get notified when certain actions occur elsewhere in the application.

• Django signals allow certain senders to notify a set of receivers when some action has taken place.

• They are used for decoupling various components of a web application.

• Signals are useful for executing code based on certain events, such as user login, object creation, etc.

• Example: Sending an email notification to the admin whenever a new user registers on...read more

I am familiar with design patterns such as Singleton, Factory, Observer, and MVC.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying the exact class of object that will be created.

• Observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

• MVC (Model-View-Controller) pattern se...read more

Convert a List of employees into a Map of Employees with ID as the key.

• Create an empty Map

• Iterate through the List of employees

• For each employee, add a key-value pair to the Map with ID as key and employee object as value

IEnumerable and IQueryable are interfaces for querying data, while ArrayList and List are collections for storing data.

• IEnumerable is used for querying data from in-memory collections, while IQueryable is used for querying data from external data sources like databases.

• ArrayList is a non-generic collection that can store any type of object, while List is a generic collection that can store a specific type of object.

• List is preferred over ArrayList as it provides type safety a...read more

Angular 10 is an updated version of Angular 8 with new features and improvements.

• Angular 10 has better performance and faster compilation time.

• Angular 10 has improved accessibility features.

• Angular 10 has introduced new features like optional strict mode and differential loading.

• Angular 10 has updated dependencies like TypeScript and RxJS.

• Angular 10 has better support for web components.

Angular is a complete rewrite of AngularJS with improved performance and features.

• Angular is a TypeScript-based framework while AngularJS is based on JavaScript.

• Angular has a component-based architecture while AngularJS uses a directive-based architecture.

• Angular has better performance and improved features like server-side rendering and improved dependency injection.

• AngularJS is no longer supported by Google and is considered outdated.

• Angular is commonly referred to as Angul...read more

ngIf is a structural directive in Angular that conditionally adds or removes elements from the DOM.

• ngIf evaluates a boolean expression and renders the element if the expression is true.

• It can be used with else, then, and ng-template to handle different scenarios.

• Conditional statements in Angular are used to execute a block of code based on a condition.

• They can be used with ngIf, ngSwitch, and ternary operators.

Program to sort employee salaries using Java 8

• Use Java 8 Stream API to sort the employee salaries

• Use Comparator to compare salaries

• Collect the sorted salaries into a list

Call, apply and bind are methods used to manipulate the 'this' keyword in JavaScript functions.

• Call and apply are used to invoke a function with a specific 'this' context and arguments.

• Call takes arguments as comma-separated values, while apply takes arguments as an array.

• Bind returns a new function with a specific 'this' context, which can be called later with arguments.

• Bind is useful for creating a new function with a fixed 'this' context, such as event handlers.

Stored procedures and functions are both database objects used to encapsulate and execute a set of SQL statements.

• Stored procedures are primarily used to perform an action, such as inserting or updating data, and may or may not return a result set.

• Functions, on the other hand, are designed to return a single value or a table of values.

• Stored procedures can have input and output parameters, while functions can only have input parameters.

• Stored procedures can be called from fun...read more

Remove duplicates from an array of strings without using a library

• Create an empty object to store unique values

• Iterate through the array and add each element to the object as a key

• Convert the object keys back to an array to get the unique values

Abstract class is a class that cannot be instantiated, while interface is a contract that a class must implement.

• Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.

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

• Abstract class can have constructors, while interface cannot.

• Abstract class can have instance variables, while interface cannot.

• Abstract class is used to provide a comm...read more

The display property in CSS specifies how an element is displayed on a webpage.

• It can be used to change the default behavior of an element, such as block or inline.

• Common values include block, inline, inline-block, none, flex, and grid.

• It can also be used to hide elements by setting it to 'none'.

The position property in CSS specifies the positioning method of an element.

• The position property can have values like static, relative, absolute, fixed, or sticky.

• Static is the default value and the element is positioned according to the normal flow of the document.

• Relative positions the element relative to its normal position.

• Absolute positions the element relative to its nearest positioned ancestor.

• Fixed positions the element relative to the viewport.

• Sticky positions the e...read more

useEffect is a hook in React that allows you to perform side effects in function components.

• useEffect is used to perform side effects in function components.

• It runs after every render by default.

• You can specify dependencies to control when the effect runs.

• Common use cases include data fetching, subscriptions, and DOM manipulations.

Yes, I have worked in API development. Methods are the functions or operations that can be performed on an API.

• API methods define the actions that can be taken by clients to interact with the API.

• Common API methods include GET, POST, PUT, and DELETE.

• GET method is used to retrieve data from the API, POST is used to create new data, PUT is used to update existing data, and DELETE is used to remove data.

• API methods can also include additional parameters or headers to provide mor...read more

SQL or stored procedure optimization techniques aim to improve performance by reducing execution time and resource usage.

• Use indexes to speed up data retrieval

• Avoid using SELECT * and instead specify only the necessary columns

• Minimize the use of functions in WHERE clauses

• Avoid using cursors and opt for set-based operations

• Regularly analyze query execution plans for potential optimizations

The SQL query to extract records based on a particular date.

• Use the SELECT statement to retrieve the desired columns from the table.

• Use the FROM clause to specify the table from which to extract the records.

• Use the WHERE clause to filter the records based on the desired date.

• Use the DATE function to convert the date string to the appropriate format if needed.

Answers to common interview questions for Senior Software Developer

• MVC life cycle involves request routing, controller execution, model binding, view rendering, and response generation

• Partial view is a reusable view component that can be rendered within other views

• Trigger in SQL is a special type of stored procedure that is automatically executed in response to certain events

• Function returns a value while stored procedure does not necessarily return a value

• OOPs concepts inclu...read more

Code a React app to change name state on a click of a button on code sandbox.

• Create a functional component with a state for name

• Render a button with an onClick event to update the name state

• Display the name state in the component

• Use CodeSandbox to test the app