4500+ Senior Software Engineer Interview Questions and Answers

ETL and ELT tools are used for extracting, transforming, and loading data in data warehousing and analytics processes.

• ETL stands for Extract, Transform, Load and involves extracting data from various sources, transforming it into a usable format, and loading it into a data warehouse or database.

• ELT stands for Extract, Load, Transform and involves extracting data, loading it into a target system, and then transforming it as needed within the target system.

• ETL tools are typical...read more

Singleton design pattern restricts the instantiation of a class to one object.

• Used when only one instance of a class is required throughout the project

• Provides a global point of access to the instance

• Can be implemented using a private constructor and a static method

• Examples include database connections, configuration settings, and logger classes

JVM architecture includes class loader, bytecode verifier, interpreter, JIT compiler, and runtime data areas. Memory management is done through garbage collection.

• JVM has class loader to load class files and bytecode verifier to check the code for security and correctness.

• Interpreter executes the bytecode and JIT compiler optimizes the code for better performance.

• Runtime data areas include method area, heap, stack, and PC registers.

• Memory management is done through garbage co...read more

OOP stands for Object-Oriented Programming. It is a programming paradigm based on the concept of objects, which can contain data and code.

• Main method can be overloaded in Java by defining multiple methods with the same name but different parameters.

• Abstraction in OOP is the concept of hiding the implementation details and showing only the necessary features of an object. Example: Car as an object with properties like color, model, and methods like start, stop.

• Inheritance in J...read more

The design pattern is used to solve a specific problem in software development.

• Design patterns are reusable solutions to common problems in software development.

• They provide a standard way to solve a problem that can be adapted to different situations.

• Examples of design patterns include Singleton, Factory, Observer, and Decorator.

• Using design patterns can improve code quality, maintainability, and scalability.

SSRS is a server-based reporting platform that allows users to create, manage, and deliver reports.

• SSRS allows users to create interactive, tabular, graphical, or free-form reports from various data sources.

• Reports can be published to a centralized report server for easy access by users.

• Users can schedule report generation and delivery, as well as subscribe to reports for automated distribution.

• SSRS supports a wide range of data sources including SQL Server, Oracle, ODBC, OLE...read more

Event loop is a mechanism that allows for asynchronous execution of code by managing the order of events in a single thread.

• Event loop continuously checks the call stack for any functions that need to be executed, and processes them in a non-blocking manner.

• Different types of queues in event loop include microtask queue (Promise callbacks), macrotask queue (setTimeout, setInterval callbacks), and animation frame queue (requestAnimationFrame callbacks).

I have implemented RE framework in 3 projects.

• Implemented RE framework in 3 projects

• Used RE framework for automating end-to-end processes

• Leveraged RE framework's modular structure for easy maintenance

• Examples: Invoice processing, Order management, HR onboarding

Self-Join is when a table is joined with itself, while Cross-Join is when every row from one table is combined with every row from another table.

• Self-Join is used to combine rows with other rows in the same table.

• Cross-Join generates a Cartesian product of the two tables involved.

• Self-Join is typically used to compare rows within the same table, like in hierarchical structures.

• Cross-Join is used when there is no common key between the two tables.

The different phases in an automation testing life cycle include planning, design, execution, and reporting.

• 1. Planning phase involves defining the scope, objectives, and resources required for automation testing.

• 2. Design phase includes creating test cases, selecting automation tools, and setting up the test environment.

• 3. Execution phase involves running the automated tests, analyzing results, and identifying defects.

• 4. Reporting phase includes generating test reports, docu...read more

Testing challenges include lack of resources, time constraints, and communication issues. Overcoming them requires proper planning and collaboration.

• Lack of resources, such as hardware or software, can hinder testing efforts

• Time constraints may lead to rushed testing and incomplete coverage

• Communication issues between team members can result in misunderstandings and errors

• Proper planning and collaboration can help overcome these challenges

• Establish clear testing goals and pri...read more

Dictionary is a generic collection while Hashtable is a non-generic collection.

• Dictionary is type-safe while Hashtable is not.

• Dictionary allows null keys and values while Hashtable does not.

• Dictionary is faster than Hashtable for small collections.

• Hashtable is thread-safe while Dictionary is not.

Fact Table contains quantitative data and measures, while Dimension Table contains descriptive attributes.

• Fact Table typically contains numerical data that can be aggregated (e.g. sales revenue, quantity sold)

• Dimension Table contains descriptive attributes for the data in the Fact Table (e.g. product name, customer details)

• Fact Table is usually normalized for efficient data storage and retrieval, while Dimension Table is denormalized for easier querying and reporting

Structure is a data type that allows different data types to be grouped together, while union is a data type that allows different data types to share the same memory location.

• Structures allocate memory for each member separately, while unions share memory for all members.

• Structures are used when different data types need to be stored together, while unions are used when only one type of data needs to be stored at a time.

• Example: struct Person { string name; int age; }; union...read more

Test Stub simulates the behavior of a module while Test Driver controls the test execution.

• Test Stub is used to simulate the behavior of a module that a module under test depends on.

• Test Driver is used to control the test execution and interact with the module under test.

• Test Stub provides fake data or functionality to the module under test.

• Test Driver orchestrates the flow of the test case and passes inputs to the module under test.

• Example: In testing a payment processing mo...read more

Merge transformation combines two datasets into one, while Merge-Join transformation combines two datasets based on a common key.

• Merge transformation combines rows from two datasets into a single dataset without any condition.

• Merge-Join transformation combines rows from two datasets based on a common key or condition.

• Merge transformation is used for combining unrelated datasets, while Merge-Join is used for joining related datasets.

• Example: Merge transformation can be used to...read more

Distributed systems are a network of independent computers that work together to achieve a common goal. Security can be maintained through encryption, authentication, access control, and monitoring.

• Distributed systems consist of multiple computers that communicate and coordinate actions to achieve a common goal.

• Security in distributed systems can be maintained through encryption of data in transit and at rest.

• Authentication mechanisms such as passwords, tokens, or biometrics ...read more

Security in MVC involves implementing authentication, authorization, and secure communication to protect web and API resources.

• Implement authentication mechanisms like username/password, tokens, or OAuth.

• Use authorization to control access to resources based on user roles and permissions.

• Secure communication by using HTTPS and encrypting sensitive data.

• Implement input validation and sanitization to prevent common security vulnerabilities like SQL injection and cross-site scri...read more

Stored procedure is a precompiled SQL code, web API HTTP verbs are GET, POST, PUT, DELETE.

• Stored procedure is a set of SQL statements that are precompiled and stored in the database for reuse.

• Web API HTTP verbs are GET, POST, PUT, DELETE used for communication between client and server.

• GET is used to retrieve data, POST is used to create data, PUT is used to update data, DELETE is used to delete data.

• Examples of web API HTTP verbs are GET https://api.example.com/users, POST h...read more

HashMap is faster than TreeMap wrto performance due to its constant time complexity for most operations.

• HashMap has O(1) time complexity for most operations while TreeMap has O(log n) time complexity.

• HashMap is implemented using an array of buckets while TreeMap is implemented using a Red-Black Tree.

• HashMap is preferred for frequent read operations while TreeMap is preferred for frequent write operations.

• HashMap is unordered while TreeMap is ordered based on the natural order...read more

Sort array of strings based on frequency of digits in each element.

• Create a dictionary to store frequency of digits in each element.

• Sort the array based on the frequency of digits using the dictionary.

• Handle ties by sorting based on the original order of elements.

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

• Abstract class can have constructors, fields, and methods with implementation.

• Interface can only have abstract methods and constants.

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

• Example: Abstract class - Animal with abstract method 'eat', Interface - Flyable with method 'fly'.

Java 8 introduced several new features including lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions: Enable functional programming in Java by expressing instances of single-method interfaces (functional interfaces) concisely.

• Functional interfaces: Interfaces with a single abstract method, such as java.util.function.Function or java.util.function.Predicate.

• Streams: Allow for processing sequences of elements in a functional style, support...read more

The digin pattern implemented for string pool is a technique to reuse string objects to optimize memory usage.

• String pool is a cache of string objects stored in memory.

• When a string is created, it is first checked if it already exists in the pool.

• If it does, a reference to the existing string object is returned instead of creating a new one.

• This helps in reducing memory consumption and improving performance.

• Examples: String s1 = "Hello"; String s2 = "Hello"; Here, s1 and s2 w...read more

Concurrent hashmap allows multiple threads to access and modify the map concurrently without causing data inconsistency.

• Concurrent hashmap is thread-safe and allows multiple threads to access and modify the map concurrently.

• It uses a technique called lock striping to divide the map into segments and apply locks to each segment instead of the entire map.

• This allows multiple threads to access different segments of the map concurrently without causing data inconsistency.

• Concurre...read more

Temporary table is a table that exists temporarily in the database and is used to store intermediate results.

• Temporary tables are created and used within a single session or transaction.

• They are stored in the tempdb database in SQL Server.

• They can be used to store intermediate results during complex queries or to simplify complex joins.

• They are automatically dropped when the session or transaction ends or when they are explicitly dropped.

• They can be created using the CREATE T...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