70+ Interview Questions and Answers

The interview questions cover topics like encapsulation, inheritance, constructors, method overloading, overriding, exception handling, and hobbies.

• Encapsulation is the process of hiding the internal details of an object and providing access through methods.

• Inheritance is a mechanism in which one class inherits the properties and behaviors of another class.

• A constructor is a special method used to initialize objects.

• Method overloading is the ability to define multiple methods...read more

The developer reviewed and sent back the bug on the same day.

• The developer may have fixed the bug quickly.

• The developer may have found the bug to be invalid or not reproducible.

• The developer may have requested more information or clarification.

• The developer may have sent the bug back for further testing or verification.

• The developer may have sent the bug back for a second opinion or review.

Data can be passed from one component to another in React using props.

• Create a parent component that renders child components

• Pass data as props from parent to child components

• Use callback functions to pass data from child to parent components

• Use context API to pass data to multiple levels of child components

• Use Redux for global state management

React uses a virtual DOM to efficiently update the actual DOM when the state changes.

• React creates a new virtual DOM tree when the state changes

• It compares the new virtual DOM tree with the previous one to find the differences

• It then updates only the necessary parts of the actual DOM to reflect the changes

• This process is called reconciliation

• React also uses a batching mechanism to group multiple state changes together for better performance

The company is currently working on implementing AI and machine learning technologies.

• AI-powered chatbots for customer service

• Machine learning algorithms for data analysis

• Computer vision for image recognition

• Natural language processing for voice assistants

• Predictive analytics for business intelligence

OOPs concepts are the principles of Object-Oriented Programming that focus on encapsulation, inheritance, and polymorphism.

• Encapsulation: bundling of data and methods that manipulate the data within a single unit

• Inheritance: ability of a class to inherit properties and methods from a parent class

• Polymorphism: ability of objects to take on multiple forms or behaviors

• Abstraction: hiding the implementation details of a class from the outside world

• Example: A car is an object that...read more

Properties can be differentiated using Spring profiles for dev, uat, and prod.

• Define profiles in application.properties or application.yml

• Use @Profile annotation to activate specific profile

• Separate property files for each profile

• Example: application-dev.properties, application-uat.properties, application-prod.properties

Interview question for Software Engineer on OOPs concepts, character repetition in a sentence, and Selenium code for login.

• OOPs concepts include inheritance, encapsulation, polymorphism, and abstraction

• To calculate character repetition in a sentence, iterate through each character and keep a count

• Selenium code to invoke a website and enter login credentials involves using the WebDriver API and locating the login elements

• Example: driver.get('https://www.example.com'), username...read more

Code to count characters in a string and output their count.

• Create an empty dictionary to store character counts.

• Loop through each character in the string and add it to the dictionary with a count of 1 if it doesn't exist, or increment the count if it does.

• Output the dictionary with the character counts.

Java is a high-level, object-oriented programming language, while C++ is a low-level, multi-paradigm language.

• Java is platform-independent, while C++ is platform-dependent.

• Java uses automatic garbage collection, while C++ requires manual memory management.

• Java does not support pointers, while C++ does.

• Java has a simpler syntax compared to C++.

• Java is more secure due to its strong type checking and exception handling mechanisms.

React has three main lifecycle methods: Mounting, Updating, and Unmounting.

• Mounting: constructor(), static getDerivedStateFromProps(), render(), componentDidMount()

• Updating: static getDerivedStateFromProps(), shouldComponentUpdate(), render(), getSnapshotBeforeUpdate(), componentDidUpdate()

• Unmounting: componentWillUnmount()

• Examples: componentDidMount() is used to fetch data from an API, componentWillUnmount() is used to clean up any resources used by the component before it i...read more

AWS platform offers a wide range of features for cloud computing services.

• Scalability: Easily scale resources up or down based on demand

• Flexibility: Choose from a variety of programming languages, databases, and operating systems

• Security: Built-in security features to protect data and applications

• Cost-effective: Pay only for the resources you use

• Reliability: High availability and redundancy to ensure uptime

• Storage options: Various storage options like S3, EBS, and Glacier

• Comp...read more

A technical interview is a job interview for positions in the technology industry where candidates are evaluated on their technical skills and knowledge.

• Technical interviews typically involve coding challenges, problem-solving exercises, and discussions about technical concepts.

• Candidates may be asked to write code on a whiteboard, solve algorithmic problems, or explain their approach to solving a technical challenge.

• Interviewers may also ask questions about the candidate's e...read more

Java 8 features include lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions allow functional programming in Java.

• Functional interfaces enable the use of lambda expressions.

• Streams provide a concise way to perform operations on collections.

• Default methods allow interfaces to have implementation.

• Date and Time API improvements.

• Nashorn JavaScript engine.

• Parallel operations on collections.

• Type annotations.

• Repeatable annotations.

• Method referen...read more

Some popular Bigdata frameworks include Apache Hadoop, Apache Spark, and Apache Flink.

• Apache Hadoop: Used for distributed storage and processing of large data sets.

• Apache Spark: In-memory data processing engine for big data analytics.

• Apache Flink: Stream processing framework with high throughput and low latency.

Different types of file formats in Hadoop include Avro, Parquet, ORC, SequenceFile, and TextFile.

• Avro

• Parquet

• ORC

• SequenceFile

• TextFile

Single inheritance allows a class to inherit from only one parent class, while multiple inheritance allows a class to inherit from multiple parent classes.

• Single inheritance: class A can inherit from class B.

• Multiple inheritance: class A can inherit from class B and class C.

• Single inheritance is simpler and easier to understand.

• Multiple inheritance can lead to ambiguity and complexity, known as the diamond problem.

• Languages like Java support single inheritance, while language...read more

Method hiding is a concept in object-oriented programming where a subclass defines a method with the same name as a method in its superclass.

• Method hiding is also known as static polymorphism or compile-time polymorphism.

• It is achieved by using the 'static' keyword in the subclass method definition.

• The subclass method with the same name as the superclass method hides the superclass method.

• Method hiding is different from method overriding, where a subclass method replaces the ...read more

Dependency injection is a design pattern used in Spring to inject dependencies into an object at runtime.

• Dependency injection is used to reduce tight coupling between classes

• Spring provides three types of dependency injection: constructor injection, setter injection, and field injection

• Constructor injection is the preferred method as it ensures that all dependencies are provided at object creation

• Setter injection is used when optional dependencies are needed

• Field injection is...read more

SQL index is used to improve the performance of queries by allowing faster data retrieval. SP and CTE are different ways to organize and execute SQL queries.

• SQL index is a data structure that improves the speed of data retrieval operations on a database table.

• Stored Procedures (SP) are precompiled SQL queries that can be reused and executed multiple times.

• Common Table Expressions (CTE) are temporary result sets that can be referenced within a SELECT, INSERT, UPDATE, or DELETE...read more

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

• Encapsulation: Objects can encapsulate data and behavior within a single unit.

• Inheritance: Objects can inherit attributes and methods from other objects.

• Polymorphism: Objects can take on multiple forms or have different behaviors based on their data type.

• Reusability: Objects and classes can be reused in different parts of a program.

• Modular...read more

Join operations combine data from two or more tables based on a related column.

• Join operations are used to retrieve data from multiple tables in a single query.

• Common types of join operations include inner join, left join, right join, and full outer join.

• Inner join returns only the matching rows from both tables, while left join returns all rows from the left table and matching rows from the right table.

• Right join is similar to left join, but returns all rows from the right t...read more

Authentication can be implemented using various methods such as OAuth, JWT, and session-based authentication.

• OAuth allows users to authenticate using third-party services such as Google or Facebook.

• JWT is a token-based authentication method that allows users to authenticate without the need for a session.

• Session-based authentication involves creating a session for the user upon successful login and storing the session ID in a cookie.

• Authentication can also be implemented usin...read more

Python function using pandas to remove duplicate rows from a dataframe.

• Import pandas library

• Use drop_duplicates() method on the dataframe

• Specify subset of columns if needed

• Example: df.drop_duplicates(subset=['column1', 'column2'])

SQL is a programming language used to manage and manipulate relational databases.

• SQL stands for Structured Query Language

• It is used to create, modify, and query databases

• SQL is used in various industries including finance, healthcare, and e-commerce

• Common SQL commands include SELECT, INSERT, UPDATE, and DELETE

Regression, sanity, and smoke testing are different types of software testing.

• Regression testing is done to ensure that new code changes do not negatively impact existing functionality.

• Sanity testing is a narrow and focused testing to quickly determine if a new functionality is working as expected.

• Smoke testing is a preliminary testing to check if the software build is stable enough for further testing.

• Regression testing is comprehensive and time-consuming, sanity testing is ...read more

Spring MVC is a framework for building web applications in Java. IOC stands for Inversion of Control, a design pattern used in Spring.

• Spring MVC is a part of the Spring Framework that provides a model-view-controller architecture for developing web applications.

• It follows the MVC pattern, where the model represents the data, the view represents the user interface, and the controller handles the requests and manages the flow of data.

• IOC, or Inversion of Control, is a principle...read more

Abstraction is hiding implementation details while polymorphism is using a single interface for multiple types.

• Abstraction allows us to focus on the essential features of an object while hiding the implementation details.

• Polymorphism allows us to use a single interface to represent multiple types of objects.

• Abstraction and polymorphism are closely related and often used together in object-oriented programming.

• For example, a car can be abstracted as a vehicle with properties l...read more

Collections in Java are classes and interfaces that provide a way to store and manipulate groups of objects.

• Collections are used to manage groups of objects in Java.

• They provide a way to store, retrieve, and manipulate data in a structured manner.

• Some examples of collections in Java include ArrayList, LinkedList, HashSet, and HashMap.

• Collections can be used to sort, search, and filter data, among other things.

Salary expectations refer to the amount of money a software engineer anticipates earning in a job.

• Salary expectations are influenced by factors such as experience, skills, location, and industry.

• Software engineers with more experience and in-demand skills may have higher salary expectations.

• Location plays a role in salary expectations as cost of living varies across different regions.

• The industry in which a software engineer works can also impact salary expectations.

• For examp...read more

SQL code to perform upsert using joins

• Use the MERGE statement in SQL to perform upsert operations

• Join the source table with the target table on the appropriate columns

• Specify the conditions for matching records and update the target table accordingly

• Insert the non-matching records from the source table into the target table

Function returns a value while procedure does not.

• Function returns a value, procedure does not

• Functions are used for calculations and return a value, procedures are used for executing a sequence of statements

• Example: Function to calculate the square of a number, Procedure to display a message

A program to generate Fibonacci series using iterative or recursive approach.

• Use a loop to generate Fibonacci series iteratively

• Use recursion to generate Fibonacci series recursively

• Start with 0 and 1 as the first two numbers in the series

• Add the previous two numbers to get the next number in the series

Long form refers to the complete or expanded version of an acronym or abbreviation.

• Long form is used to provide clarity and avoid confusion.

• It is commonly used in technical fields and academia.

• Examples include NASA (National Aeronautics and Space Administration) and AIDS (Acquired Immune Deficiency Syndrome).

Program to check if a given string is a palindrome or not.

• Convert the string to lowercase to ignore case sensitivity

• Use two pointers, one at the start and one at the end of the string

• Compare the characters at both pointers and move them towards each other

• If all characters match, the string is a palindrome

A string is a sequence of characters.

• Strings are used to represent text in programming languages.

• They are enclosed in quotes, either single or double.

• Strings can be concatenated using the + operator.

• Common string operations include length, substring, and replace.

IC555 is a popular integrated circuit used in electronic devices for generating accurate and stable timing signals.

• IC555 is a timer IC that can be used in various applications such as oscillators, pulse generators, and frequency dividers.

• It is commonly used in electronic circuits for controlling the timing of events.

• IC555 has three operational modes: monostable, astable, and bistable.

• In the monostable mode, it generates a single pulse of a specific duration.

• In the astable mod...read more

Data structures are ways of organizing and storing data in a computer so that it can be accessed and used efficiently.

• Data structures are used to manage large amounts of data efficiently

• They can be implemented using arrays, linked lists, trees, graphs, and more

• Examples include stacks, queues, hash tables, and binary search trees

Multi threading is the ability of a program to perform multiple tasks concurrently.

• Allows for efficient use of CPU resources

• Improves program responsiveness and user experience

• Can be used for parallel processing and background tasks

• Examples include web servers, video players, and gaming applications

Lambda function is an anonymous function that can be passed as an argument or returned as a value.

• Lambda functions are also known as anonymous functions.

• They are commonly used in functional programming languages.

• Lambda functions can be used to create closures.

• They can be used to write concise and readable code.

• Example: lambda x: x*2 defines a function that doubles its input.

Finally block is used in exception handling to execute code regardless of whether an exception is thrown or not.

• Finally block is used in conjunction with try and catch blocks in exception handling.

• Code inside the finally block will always be executed, even if an exception is thrown.

• Common use cases include closing resources like files or database connections.

• Example: try { // code that may throw an exception } catch(Exception e) { // handle exception } finally { // cleanup co...read more

Iterate through array to find second max number

• Iterate through the array and keep track of the largest and second largest numbers

• Compare each element with the largest and second largest numbers to update them accordingly

• Return the second largest number found

Web API filters and routing are essential for managing and directing traffic to the appropriate endpoints.

• Filters can be used to modify or validate incoming requests before they reach the endpoint.

• Routing determines which endpoint should handle a particular request based on the URL or other criteria.

• Filters and routing can be configured using frameworks like Express.js or ASP.NET.

• Examples of filters include authentication middleware, rate limiting, and input validation.

• Exampl...read more

I am familiar with technologies such as React, Node.js, Docker, Kubernetes, and AWS.

• React

• Node.js

• Docker

• Kubernetes

• AWS

The statue of four lions is a famous monument located in India.

• The statue is located in the city of Delhi.

• It was built in the 16th century by Emperor Ashoka.

• The four lions represent power, courage, pride, and confidence.

• The statue is a symbol of Indian sovereignty and is featured on the national emblem.

• It is also a popular tourist attraction.

SQL joins are used to combine rows from two or more tables based on a related column between them.

• SQL joins are used to retrieve data from multiple tables based on a related column between them

• Types of SQL joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• INNER JOIN returns rows when there is at least one match in both tables

• LEFT JOIN returns all rows from the left table and the matched rows from the right table

• RIGHT JOIN returns all rows from the right table and ...read more

Foreign key is a field in a database table that links to a primary key in another table.

• Used to establish a relationship between two tables in a database

• Ensures referential integrity

• Prevents invalid data from being inserted into the foreign key column

• Example: CustomerID in Orders table linking to CustomerID in Customers table

Python is dynamically typed, interpreted language while Java is statically typed, compiled language.

• Python is easier to learn and write code quickly

• Java is more verbose and requires more boilerplate code

• Python is better for scripting and data analysis

• Java is better for enterprise applications and large-scale projects

• Python has a simpler syntax and is more readable

• Java has better performance and is more secure

Hadoop is a distributed storage system while Spark is a fast and general-purpose cluster computing system.

• Hadoop is primarily used for batch processing of large datasets, while Spark is used for real-time data processing.

• Hadoop uses MapReduce for processing data, while Spark uses in-memory processing for faster computation.

• Spark is faster than Hadoop due to its ability to store data in-memory and perform multiple operations in memory.

• Hadoop is more suitable for processing lar...read more

F1 score is a measure of a test's accuracy that considers both the precision and recall of the test.

• F1 score is the harmonic mean of precision and recall.

• It is calculated using the formula: 2 * (precision * recall) / (precision + recall)

• F1 score ranges from 0 to 1, where 1 is the best possible score.

• It is commonly used in binary classification tasks.

SQL is a standard language for managing relational databases, while PL/SQL is a procedural extension for SQL.

• SQL is a standard language used to manage and manipulate data in relational databases.

• PL/SQL is a procedural language extension for SQL, allowing for more complex programming capabilities.

• SQL is used for querying and updating data, while PL/SQL is used for writing procedural code like loops and conditional statements.

• SQL is declarative, while PL/SQL is procedural.

Hashmap is not synchronized and allows null values, while Hashtable is synchronized and does not allow null values.

• Hashmap is faster than Hashtable due to lack of synchronization.

• Hashmap allows null values while Hashtable does not.

• Hashtable is thread-safe while Hashmap is not.

• Both are used to store key-value pairs.

• Hashmap is part of the Java Collections Framework while Hashtable is a legacy class.

Networking concepts in computer science involve understanding how data is transmitted and communicated between devices on a network.

• Understanding of OSI model and TCP/IP protocol suite

• Knowledge of IP addressing, subnetting, and routing

• Familiarity with network devices such as routers, switches, and firewalls

• Understanding of network security concepts like encryption and authentication

• Experience with network troubleshooting and monitoring tools

Var, const, and scope are key concepts in JavaScript for declaring variables and managing their scope.

• Var is used to declare variables with function scope.

• Const is used to declare variables with block scope that cannot be reassigned.

• Scope refers to the visibility and accessibility of variables within a program.

Annotations are used in Spring to provide metadata to the Spring framework.

• Annotations are used to configure Spring beans and their dependencies.

• Some commonly used annotations in Spring are @Autowired, @Component, @Controller, @Service, and @Repository.

• Annotations can also be used for AOP (Aspect-Oriented Programming) in Spring.

• Annotations can be used to define transaction boundaries in Spring.

• Annotations can be used to handle exceptions in Spring.

• Annotations can be used to d...read more

Threads are lightweight processes that enable multitasking within a single process.

• Threads share the same memory space as the parent process

• Threads can communicate with each other through shared memory

• Threads can be created and destroyed dynamically

• Examples include GUI applications, web servers, and video games

Polymorphism is the ability of a single function or method to operate on different data types.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: Inheritance in object-oriented programming languages like Java allows for polymorphism.

Method Overriding is a feature that allows a subclass to provide a specific implementation of a method that is already provided by its superclass.

• Occurs in inheritance when a subclass provides a specific implementation of a method that is already provided by its superclass

• The method in the subclass must have the same name, return type, and parameters as the method in the superclass

• The overridden method in the subclass should have the same or broader access modifier than the m...read more

Types of test steps in software testing

• Unit testing - testing individual units or components of the software

• Integration testing - testing how different units or components work together

• System testing - testing the entire system as a whole

• Acceptance testing - testing if the software meets the requirements and is ready for release

• Regression testing - testing to ensure that changes or updates to the software did not introduce new bugs

• Performance testing - testing the software's ...read more

DBMS concepts in computer science involve understanding database design, management, and querying.

• Understanding database design principles such as normalization and denormalization

• Knowledge of database management tasks like indexing, transactions, and concurrency control

• Familiarity with querying languages like SQL and query optimization techniques

• Understanding of data modeling and relationships between entities in a database

• Knowledge of different types of database systems lik...read more

Cross join combines each row from the first table with each row from the second table.

• Cross join does not require any common columns between the two tables.

• It results in a Cartesian product of the two tables.

• Useful when you want to combine all rows from one table with all rows from another table.