600+ Senior Software Developer Interview Questions and Answers

RANK() assigns a unique rank to each row based on the specified column, while ROW_NUMBER() assigns a unique sequential row number to each row.

• RANK() may have gaps in the ranking if there are ties, while ROW_NUMBER() will not have any gaps.

• RANK() will assign the same rank to rows with the same value, while ROW_NUMBER() will assign a unique row number to each row.

• ROW_NUMBER() is used to generate a unique sequential number for each row in a result set, while RANK() is used to as...read more

Slice is a method that extracts a portion of an array without modifying the original array, while splice is a method that adds or removes elements from an array.

• Slice returns a shallow copy of a portion of an array based on start and end index parameters.

• Splice can add new elements to an array or remove existing elements by specifying the start index and number of elements to remove.

• Example: const arr = [1, 2, 3, 4, 5]; arr.slice(1, 3) will return [2, 3], while arr.splice(1, ...read more

Skip, SkipWhile, and SkipLast are LINQ methods used to skip elements in a sequence.

• Skip(n) skips the first n elements in a sequence.

• SkipWhile(predicate) skips elements in a sequence while the predicate is true.

• SkipLast(n) skips the last n elements in a sequence.

• LINQ is a language integrated query that allows querying data from different data sources.

• SQL is a database management system that uses Structured Query Language to manage data.

• LINQ is used to query data from different...read more

4

• Extensive experience in software development

• Strong knowledge of programming languages and frameworks

• Proficient in problem-solving and debugging

• Ability to design and implement complex software systems

N+1 SELECT problem in Hibernate occurs when a query results in N+1 database queries being executed instead of just one.

• Occurs when a query fetches a collection of entities and then for each entity, another query is executed to fetch related entities individually

• Can be resolved by using fetch joins or batch fetching to fetch all related entities in a single query

• Example: Fetching a list of orders and then for each order, fetching the customer details separately

Find maximum for each contiguous subarray of size k from an array of size n.

• Iterate through the array and keep track of maximum for each subarray of size k

• Use a sliding window approach to efficiently calculate maximum for each subarray

• Time complexity: O(n)

• Example: arr = [10, 5, 2, 7, 1, 9, 4], k = 3, output = [10, 7, 7, 9, 9]

Spring Boot offers basic annotations like @Controller, @RestController, @Service, @Repository, @Component.

• @Controller - Used to mark a class as a Spring MVC controller.

• @RestController - Combination of @Controller and @ResponseBody, used to create RESTful web services.

• @Service - Used to mark a class as a service component in Spring.

• @Repository - Used to mark a class as a data access component in Spring.

• @Component - General-purpose stereotype annotation for any Spring-managed c...read more

React context is a built-in feature for passing data through the component tree, while React Redux is a library for managing global state in React applications.

• React context is used for passing data down the component tree without having to pass props manually at every level.

• React Redux is a library that provides a centralized store for managing global state in a React application.

• React context is built into React, while React Redux is a separate library that needs to be inst...read more

StringBuffer is synchronized and thread-safe, while StringBuilder is not synchronized and faster.

• StringBuffer is synchronized, making it thread-safe for use in multi-threaded environments.

• StringBuilder is not synchronized, making it faster but not thread-safe.

• Use StringBuffer when thread safety is needed, and StringBuilder for better performance in single-threaded scenarios.

Prototype chain in JavaScript is the mechanism by which objects inherit properties and methods from other objects.

• In JavaScript, each object has a private property which holds a link to another object called its prototype.

• If a property or method is not found on an object, JavaScript will look for it in the object's prototype, and so on up the chain.

• This allows for inheritance in JavaScript, where objects can inherit properties and methods from their prototypes.

The answer provides regex patterns to extract specific information from a given text.

• Use the appropriate regex pattern to match the desired information

• Consider any variations or patterns in the text that may affect the regex

• Test the regex patterns with sample texts to ensure accuracy

Stored procedures, packages, functions, and joins are all database concepts used to improve performance and functionality.

• Stored procedures are precompiled SQL statements that can be executed multiple times.

• Packages are a collection of related procedures, functions, and variables that can be used together.

• Functions are similar to stored procedures but return a value.

• Joins are used to combine data from multiple tables based on a common column.

Answers to questions related to microservice architecture, circuit breaker, service discovery, disadvantages of microservice, disadvantage of stream API, and default methods in functional interface.

• Microservice architecture allows for scalability, flexibility, and easier maintenance of complex systems.

• Circuit breaker is a design pattern used to prevent cascading failures in distributed systems.

• Service discovery is the process of automatically detecting and locating services i...read more

The @RestController annotation in Spring Boot is used to define a class as a RESTful controller.

• Used to create RESTful web services in Spring Boot

• Combines @Controller and @ResponseBody annotations

• Eliminates the need to annotate every method with @ResponseBody

• Returns data directly in the response body as JSON or XML

Hibernate provides several concurrency strategies like optimistic locking, pessimistic locking, and versioning.

• Optimistic locking: Allows multiple transactions to read a row simultaneously, but only one can update it at a time.

• Pessimistic locking: Locks the row for exclusive use by one transaction, preventing other transactions from accessing it.

• Versioning: Uses a version number to track changes to an entity, allowing Hibernate to detect and resolve conflicts.

Deep copy creates a new copy of an object with all nested objects also copied, while shallow copy creates a new copy of an object with references to nested objects.

• Deep copy creates a new object and recursively copies all nested objects, resulting in a completely independent copy.

• Shallow copy creates a new object but only copies references to nested objects, so changes in nested objects will reflect in both the original and copied objects.

• Example: deep copy - copying an array...read more

There are 204 squares on a chessboard.

• The chessboard has 64 squares in total.

• Each square can be divided into smaller squares, such as 1x1, 2x2, 3x3, etc.

• The total number of squares can be calculated by adding the squares of all sizes together.

Proficient in Java, Python, and JavaScript.

• Java

• Python

• JavaScript

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

Override and virtual are keywords in C# used for method overriding and polymorphism.

• Override keyword is used to provide a new implementation for a method in a derived class that is already defined in a base class.

• Virtual keyword is used to allow a method to be overridden in a derived class.

• Override keyword is used in the derived class to indicate that a method overrides a base class method.

• Virtual keyword is used in the base class to indicate that a method can be overridden i...read more

CTE is a temporary result set that can be referenced within a SELECT, INSERT, UPDATE, or DELETE statement in SQL.

• CTEs help improve readability and maintainability of complex SQL queries.

• They can be recursive, allowing for hierarchical data querying.

• CTEs are defined using the WITH keyword followed by the CTE name and query.

• Example: WITH cte_name AS (SELECT * FROM table_name) SELECT * FROM cte_name;

To use a method in a different file in a Spring MVC project, you need to create a bean for the class containing the method and then inject it where needed.

• Create a bean for the class containing the method in the Spring configuration file

• Use @Autowired annotation to inject the bean where the method needs to be used

• Ensure the class containing the method is in the component scan path

Annotations used in Spring Boot projects with explanations

• 1. @RestController - Used to define a controller and automatically includes @ResponseBody in all methods.

• 2. @RequestMapping - Maps HTTP requests to handler methods of MVC and REST controllers.

• 3. @Autowired - Used for automatic dependency injection.

• 4. @Component - Indicates that a class is a Spring component.

• 5. @Service - Indicates that a class is a service component in the business layer.

• 6. @Repository - Indicates that...read more

Independent microservices communicate through APIs, messaging queues, or event-driven architecture.

• Use RESTful APIs for synchronous communication between microservices

• Implement messaging queues like RabbitMQ or Kafka for asynchronous communication

• Leverage event-driven architecture with tools like Apache Kafka or AWS SNS/SQS

• Consider gRPC for high-performance communication between microservices

Use efficient data structures and algorithms to handle large data sets.

• Use indexing and partitioning to break down data into manageable chunks.

• Implement caching and lazy loading to reduce memory usage.

• Use parallel processing and distributed computing to improve performance.

• Optimize database queries and use NoSQL databases for scalability.

• Consider using data compression and encryption for security and storage efficiency.

Abstract class can have implementation while interface cannot.

• Abstract class can have constructors while interface cannot.

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

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

• Abstract class can have instance variables while interface cannot.

• Example of abstract class: public abstract class Animal { public void eat() { System.out.println('Eating'); } }

• Ex...read more

Functions return a value while stored procedures do not.

• Functions can be used in SQL statements while stored procedures cannot.

• Functions can be called from within stored procedures.

• Functions can be used in views while stored procedures cannot.

• Functions can have input parameters while stored procedures can have both input and output parameters.

Memory for a string in Java is allocated on the heap, with a reference stored on the stack.

• Strings in Java are immutable, so once created they cannot be changed.

• String objects are stored on the heap, while references to them are stored on the stack.

• String literals are stored in a special memory area called the String Pool.

• String objects can also be created using the 'new' keyword.

Multithreading is the concurrent execution of multiple threads to achieve parallelism and improve performance.

• Multithreading allows multiple threads to run concurrently within a single process.

• It enables parallel execution of tasks, improving performance and responsiveness.

• Background worker is a component that simplifies multithreading by providing a dedicated thread for executing time-consuming tasks in the background.

• It allows the main thread to remain responsive and not ge...read more

String is immutable while StringBuilder is mutable.

• String is a sequence of characters that cannot be modified once created.

• StringBuilder is a dynamic object that can be modified and manipulated.

• String concatenation creates a new string object while StringBuilder modifies the existing object.

• String is thread-safe while StringBuilder is not.

• Use String for small strings and StringBuilder for large strings or frequent manipulations.

Method references provide a more concise way to refer to methods by name instead of using lambda expressions.

• Method references can make code more readable and maintainable by reducing boilerplate code.

• They can be used to refer to static methods, instance methods, and constructors.

• Example: list.forEach(System.out::println) is equivalent to list.forEach(item -> System.out.println(item)).

To create a file and append text, use file handling functions in the programming language.

• Open the file in append mode

• Write the text to the file

• Close the file

Types of hashmaps in Java include HashMap, LinkedHashMap, and TreeMap.

• HashMap: basic implementation, no order guaranteed

• LinkedHashMap: maintains insertion order

• TreeMap: sorted by natural order or custom comparator

A degenerate dimension is a dimension that consists of only one attribute or column.

• It is typically used when a dimension table has only one column and no other attributes.

• It is often denormalized and included directly in the fact table.

• Example: a date dimension with only a date column can be considered a degenerate dimension.

Virtual functions in C++ allow a function to be overridden in a derived class, enabling polymorphic behavior.

• Virtual functions are declared in a base class with the 'virtual' keyword.

• They are meant to be overridden in derived classes to provide specific implementations.

• When a virtual function is called through a base class pointer or reference, the actual function to be executed is determined at runtime based on the object's type.

• Example: class Shape { virtual void draw() { ....read more

OLAP is used for analyzing historical data for decision-making, while OLTP is used for managing real-time transactional data.

• OLAP stands for Online Analytical Processing, used for complex queries and data analysis.

• OLTP stands for Online Transaction Processing, used for managing real-time transactional data.

• OLAP databases are optimized for read-heavy workloads, while OLTP databases are optimized for write-heavy workloads.

• OLAP databases typically have denormalized data structur...read more

The Observer design pattern is used to define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

• The Observer pattern involves two main components: the Subject (which maintains a list of observers and notifies them of changes) and the Observer (which registers with the Subject to receive updates)

• Real-world example: a weather station broadcasting weather updates to multiple display devices (...read more

Communication between Java and C++ applications can be achieved using various methods such as JNI, sockets, or web services.

• Use Java Native Interface (JNI) to call C++ code from Java and vice versa

• Implement socket programming for inter-process communication between Java and C++ applications

• Utilize web services like REST or SOAP for communication between Java and C++ applications

In Java, deadlock can be handled by using techniques like avoiding nested locks, using timeout, and using the java.util.concurrent package.

• Avoid nested locks to prevent potential deadlocks.

• Use timeout when acquiring locks to prevent indefinite waiting.

• Utilize java.util.concurrent package classes like ReentrantLock and Semaphore for more advanced synchronization control.

Designing an app like Uber involves creating a platform for connecting riders with drivers for on-demand transportation services.

• Develop a user-friendly interface for riders to request rides and for drivers to accept requests.

• Implement a real-time tracking system to show the location of drivers and estimated arrival times.

• Incorporate a payment system for seamless transactions between riders and drivers.

• Include a rating system for both riders and drivers to provide feedback on...read more

Considerations for managing millions of responses in a client-server application

• Implement efficient data storage and retrieval mechanisms, such as using a distributed database or caching

• Optimize network communication by minimizing unnecessary data transfer and using compression techniques

• Scale the server infrastructure horizontally to handle increased load, such as using load balancers and auto-scaling

• Implement asynchronous processing for time-consuming tasks to prevent block...read more

Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and the new Date and Time API.

• Lambda expressions allow you to write more concise code by providing a way to pass functions as arguments.

• Functional interfaces are interfaces with a single abstract method, which can be implemented using lambda expressions.

• Streams provide a way to work with sequences of elements and perform aggregate operations on them.

• The new Date and Time API p...read more

SP stands for Stored Procedure which is a pre-compiled SQL code while Query is a statement used to retrieve data from a database.

• SP is faster than Query as it is pre-compiled

• SP can be used to execute complex logic and calculations

• Query is used to retrieve data from a database

• SP can be used to improve database security by granting access to only specific procedures

• Query can be used to filter, sort and group data

A controller is used for handling user requests while an API controller is used for handling API requests.

• A controller is used for rendering views while an API controller is used for returning data in JSON format.

• API controllers are usually lighter and faster than regular controllers.

• API controllers are often used for building RESTful APIs.

• Examples of API frameworks that use API controllers include Laravel and ASP.NET Core.

Code to find square of series divisible by 3 using lambda function.

• Create a list of numbers in the series

• Use filter() function with lambda function to filter numbers divisible by 3

• Use map() function with lambda function to find square of each number

Java program to capitalize first letter of each word in a given string

• Split the input string by space to get individual words

• Iterate through each word and capitalize the first letter

• Join the words back together to form the final capitalized string

I would use memory profiling tools to identify the source of the leaks and then fix them by properly managing memory allocation and deallocation.

• Use memory profiling tools like Valgrind or Instruments to identify the source of the leaks

• Review the code to ensure proper memory allocation and deallocation practices are being followed

• Implement smart pointers or garbage collection to automatically manage memory

• Use static code analysis tools to catch potential memory leaks during d...read more