30+ Cognizant Interview Questions and Answers

DBMS is a software system that manages databases and their access. ACID properties ensure data consistency and reliability.

• DBMS stands for Database Management System

• It is a software system that manages databases and their access

• ACID properties ensure data consistency and reliability

• ACID stands for Atomicity, Consistency, Isolation, and Durability

• Atomicity ensures that a transaction is treated as a single unit of work

• Consistency ensures that the database remains in a valid sta...read more

Constructors are special methods used to initialize objects, while methods are regular functions that perform specific tasks.

• Constructors have the same name as the class, while methods have unique names.

• Constructors are called automatically when an object is created, while methods need to be called explicitly.

• Constructors do not have a return type, while methods have a return type.

• Constructors are used to set initial values of instance variables, while methods can perform var...read more

OOPs stands for Object-Oriented Programming. It is used in Java to create modular programs and reusable code.

• OOPs is a programming paradigm that focuses on objects and their interactions

• Java is an object-oriented language that supports encapsulation, inheritance, and polymorphism

• OOPs allows for code reusability, modularity, and easier maintenance

• Example: creating a class for a car object with properties like make, model, and year, and methods like start and stop

The purpose of a default constructor is to initialize the object's instance variables with default values.

• A default constructor is automatically provided by the compiler if no constructor is defined in the class.

• It is used to create an object of the class with default values for its instance variables.

• Default constructors are useful when we want to create an object without passing any initial values.

Access modifiers control the visibility and accessibility of classes, methods, and variables in Java.

• public access modifier allows a class, method, or variable to be accessed from any other class.

• default access modifier (no keyword) allows a class, method, or variable to be accessed only within the same package.

• To connect Java to a database, you can use JDBC (Java Database Connectivity) API.

• The superclass of all classes in Java is the Object class.

• SQL query to delete the last...read more

Java is a high-level programming language used for developing applications. OOPs concepts are the principles of object-oriented programming. String is a sequence of characters.

• Java is an object-oriented language that is platform-independent.

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

• String is a class in Java that represents a sequence of characters.

• Types of strings include immutable, mutable, and interned strings.

The main method is static because it needs to be called by the Java Virtual Machine (JVM) without creating an instance of the class.

• Static methods can be called directly using the class name, without creating an object of the class.

• The main method is the entry point of a Java program, and it needs to be called by the JVM to start the execution.

• If the main method were not static, we would need to create an object of the class containing the main method to call it, which is not...read more

Abstraction focuses on hiding the implementation details while encapsulation focuses on bundling the data and methods that operate on the data into a single unit.

• Abstraction is about hiding the complexity of the implementation and showing only the necessary details to the user.

• Encapsulation is about bundling the data and methods that operate on the data into a single unit.

• Abstraction allows for creating simple interfaces for complex systems.

• Encapsulation helps in achieving da...read more

Database connectivity code implementation involves establishing a connection between a database and a software application.

• Use appropriate database drivers for the specific database management system (e.g. JDBC for MySQL, SQLite3 for SQLite).

• Establish a connection using connection strings with necessary credentials (username, password, database name, host).

• Execute SQL queries to interact with the database (e.g. SELECT, INSERT, UPDATE, DELETE).

• Handle exceptions and errors that...read more

To test a website on different devices, use responsive design testing tools, emulators, physical devices, and browser developer tools.

• Use responsive design testing tools like BrowserStack or Responsinator to simulate different screen sizes.

• Utilize emulators like Android Studio's emulator or Xcode's simulator to test on various mobile devices.

• Test on physical devices to ensure accurate performance and user experience.

• Use browser developer tools like Chrome DevTools to simulate...read more

Java is a high-level programming language. String is a sequence of characters. Dependency Injection is a design pattern.

• Java is an object-oriented language with features like platform independence, automatic memory management, and multithreading.

• String is a class in Java used to represent a sequence of characters. It is immutable and can be concatenated using the '+' operator.

• Dependency Injection is a design pattern used to remove hard-coded dependencies between objects. It a...read more

Tree traversal code implementation involves visiting each node in a tree data structure in a specific order.

• There are three main types of tree traversal: in-order, pre-order, and post-order.

• In-order traversal visits the left subtree, then the root, then the right subtree.

• Pre-order traversal visits the root, then the left subtree, then the right subtree.

• Post-order traversal visits the left subtree, then the right subtree, then the root.

Constructor is a special method used to initialize an object, while a method is a function that performs a specific task.

• Constructors are called automatically when an object is created, while methods need to be called explicitly.

• Constructors have the same name as the class, while methods can have any name.

• Constructors can have parameters, while methods may or may not have parameters.

• API call process involves making requests to an API endpoint, sending data, and receiving a re...read more

Code to reverse a string

• Create an empty string to store the reversed string

• Loop through the original string from end to start

• Append each character to the empty string

• Return the reversed string

An Epic is a large body of work that can be broken down into smaller tasks called User Stories.

• Epic is a high-level requirement that is too large to be completed in a single iteration.

• User Story is a small, specific piece of work that can be completed in a single iteration.

• Epics are usually broken down into multiple User Stories for implementation.

• User Stories are more detailed and focused compared to Epics.

• Example: Epic - Develop a new feature for the website. User Story - A...read more

Final is an adjective, finally is an adverb, and finalize is a verb.

• Final is used to describe something that is last or ultimate (e.g. final exam)

• Finally is used to indicate the end of a series of events or actions (e.g. finally, we reached our destination)

• Finalize is used to complete or finish something (e.g. finalize a contract)

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

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

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

Java is independent because of its platform-independent nature.

• Java code is compiled into bytecode which can run on any platform with a JVM.

• It follows the 'Write Once, Run Anywhere' (WORA) principle.

• Java's platform independence is achieved through its architecture and class libraries.

• Java's platform independence makes it a popular choice for developing cross-platform applications.

C++ is a high-level programming language used for developing system software, application software, and video games.

• C++ is an extension of the C programming language

• It supports object-oriented programming concepts like classes, inheritance, polymorphism, etc.

• It is a compiled language and provides low-level memory manipulation features

• C++ is widely used in developing operating systems, device drivers, game engines, and financial software

• Some popular C++ libraries are STL, Boos...read more

Abstract classes are used to provide a common interface and partial implementation for related classes.

• Abstract classes are used when you want to create a base class that cannot be instantiated on its own but can be inherited by other classes.

• They are useful when you want to define common methods and properties that multiple related classes should have.

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

• Abstract methods are declared without an implementation and ...read more

final keyword is used in Java to make a variable, method or class unchangeable or unextendable.

• final variables cannot be reassigned

• final methods cannot be overridden

• final classes cannot be extended

• final keyword is used for optimization in Java

• final keyword is used to ensure immutability in Java

Authentication is the process of verifying the identity of a user, while authorization is the process of granting access to specific resources.

• Authentication confirms the identity of a user through credentials such as username and password.

• Authorization determines what resources a user can access based on their role or permissions.

• Examples of authentication include logging into a website or entering a PIN at an ATM.

• Examples of authorization include granting access to certain ...read more

The increment operator is used to increase the value of a variable by 1.

• The increment operator is denoted by ++.

• It can be used with both integers and floating-point numbers.

• It can be used as a prefix (++x) or postfix (x++).

• When used as a prefix, the value is incremented before the expression is evaluated.

• When used as a postfix, the value is incremented after the expression is evaluated.

• Example: int x = 5; x++; // x is now 6

• Example: int y = 10; ++y; // y is now 11

JDBC-SQL is a Java API for connecting and executing SQL queries on a database.

• JDBC stands for Java Database Connectivity

• It allows Java programs to interact with databases using SQL

• JDBC provides classes and interfaces for connecting to a database, sending queries, and retrieving results

• Example: Establishing a connection to a database, creating a statement, executing queries, and processing results

The volatile keyword in software engineering is used to indicate that a variable's value can be modified by multiple threads.

• Volatile keyword ensures that the variable's value is always read from and written to the main memory, rather than cached in a thread's local cache.

• It is used to prevent unexpected behavior in multi-threaded environments where multiple threads may access and modify the same variable simultaneously.

• The volatile keyword is often used in scenarios where va...read more

I have experience working with various software including Microsoft Office Suite, SAP, Oracle, and HRIS systems.

• Microsoft Office Suite

• SAP

• Oracle

• HRIS systems

An abstract class is a class that cannot be instantiated and is meant to be subclassed.

• An abstract class can have abstract methods that must be implemented by its subclasses.

• An abstract class can also have non-abstract methods that can be inherited by its subclasses.

• An abstract class provides a common interface for its subclasses.

• An abstract class can have instance variables and constructors.

• An abstract class cannot be instantiated directly but can be used as a reference type...read more

Appraisal email to candidate

• Start with a positive opening, mentioning the candidate's strengths

• Provide specific examples of the candidate's achievements or contributions

• Highlight areas for improvement in a constructive manner

• End on a positive note, expressing confidence in the candidate's potential

• Offer support for any further development or training opportunities

DBMS is a software that manages databases, while RDBMS is a type of DBMS that uses a relational model.

• DBMS stands for Database Management System

• It is a software that allows users to create, manipulate, and manage databases

• RDBMS is a type of DBMS that organizes data into tables with rows and columns

• It enforces the relational model and supports SQL for querying and managing data

• Examples of DBMS: MySQL, Oracle, SQL Server

• Examples of RDBMS: PostgreSQL, SQLite, MySQL

Test cases for data grid involve verifying data display, sorting, filtering, pagination, editing, and deleting functionalities.

• Verify data is displayed correctly in the grid

• Test sorting functionality by sorting columns in ascending and descending order

• Test filtering functionality by applying filters and checking if data is displayed correctly

• Test pagination by navigating through multiple pages of data

• Test editing functionality by updating data in the grid

• Test deleting functio...read more

The volume of a cabin refers to the amount of space inside the cabin.

• Volume can be calculated by multiplying the length, width, and height of the cabin.

• For example, if a cabin is 10 feet long, 8 feet wide, and 6 feet high, the volume would be 480 cubic feet.

• Volume is often measured in cubic units such as cubic feet or cubic meters.

Code Sandbox allows running tasks for front-end development

• Open Code Sandbox and create a new project

• Add necessary dependencies and files

• Run tasks using npm scripts or command line

• Examples: build, start, test

Priority and severity are used in software testing to determine the urgency and impact of a defect.

• Priority is the level of importance assigned to a defect, based on factors like business impact and customer requirements.

• Severity is the impact of a defect on the system, ranging from minor inconveniences to critical failures.

• Examples: A spelling mistake in a button label may have low severity but high priority if it affects user experience. A system crash would have high sever...read more

I have over 10 years of experience in sourcing candidates for various positions in operations and HR.

• Utilized job boards, social media, and networking events to source qualified candidates

• Developed relationships with staffing agencies and headhunters to expand candidate pool

• Implemented employee referral programs to encourage internal sourcing

• Utilized applicant tracking systems to streamline sourcing process