50+ Cognizant Interview Questions and Answers

NullPointerException is a runtime exception that occurs when a program tries to access or use an object reference that is null.

• It is a common exception in Java programming.

• It is thrown when a program attempts to use an object reference that has not been initialized.

• It indicates that there is an attempt to access or invoke a method on an object that is null.

• Example: String str = null; str.length();

Yes, by using the super() method in the derived class.

• super() method calls the base class method

• Derived class must inherit from the base class

• Example: class Derived(Base): def method(self): super().method()

Access specifiers define the level of access to class members. They ensure encapsulation and data hiding in object-oriented programming.

• Access specifiers are keywords used in class definitions to specify the access level of class members.

• There are three access specifiers in C++: public, private, and protected.

• Public members can be accessed from anywhere in the program, while private members can only be accessed within the class.

• Protected members can be accessed within the cla...read more

My smartphone is the most important gadget in my life.

• My smartphone helps me stay connected with family and friends

• I use it for work-related communication and tasks

• It serves as a source of entertainment during leisure time

• I can access important information and services through it

• It also serves as a camera for capturing memories

• Examples: iPhone, Samsung Galaxy, Google Pixel

Call by value and call by reference are two ways of passing arguments to a function.

• Call by value passes a copy of the argument value to the function.

• Call by reference passes a reference to the memory location of the argument.

• Call by value is used for simple data types like int, float, etc.

• Call by reference is used for complex data types like arrays, structures, etc.

C++ supports polymorphism through virtual functions and inheritance.

• Polymorphism allows objects of different classes to be treated as if they were of the same class.

• Virtual functions are declared in the base class and overridden in the derived class.

• Dynamic binding is used to determine which function to call at runtime.

• Examples include function overriding, templates, and operator overloading.

Answer to a technical interview question for Associate Software Engineer position.

• For exceptional handling, use try-catch block

• To print prime numbers till given digit, use a loop and check for prime numbers

• To print words of a sentence in reverse order, split the sentence into words and print in reverse order

• To swap 2 digits using 2 variables, use arithmetic operations

• For searching algorithm, use linear search or binary search depending on the data

• Provide additional examples o...read more

Encapsulation is hiding implementation details while abstraction is hiding unnecessary details.

• Encapsulation is achieved through access modifiers like private, protected, and public.

• Abstraction is achieved through abstract classes and interfaces.

• Encapsulation is used to protect data from outside interference.

• Abstraction is used to provide a simplified view of a complex system.

• Example of encapsulation: Getters and setters in a class.

• Example of abstraction: A car dashboard that...read more

OOPs stands for Object-Oriented Programming. It is a programming paradigm based on the concept of objects.

• OOPs is a way of organizing and designing code around objects

• Variables are used to store data within an object

• In OOPs, variables are also known as properties or attributes

• Variables can have different access modifiers like public, private, protected

• Example: A car object can have properties like color, model, and speed

String buffer and string builder are classes in Java used for manipulating strings.

• String buffer is a mutable sequence of characters that can be modified without creating a new object.

• String builder is similar to string buffer but is not synchronized, making it faster in single-threaded applications.

• Both classes provide methods for appending, inserting, deleting, and replacing characters in a string.

• Example: StringBuffer sb = new StringBuffer("Hello"); sb.append(" World"); Sy...read more

Code for palindrome in any language like c c++ or c#

• Take input string from user

• Reverse the string

• Compare original and reversed string

• If same, then it is a palindrome

IOT is the interconnection of physical devices, while AngularJS is a JavaScript framework for web development.

• IOT enables devices to communicate and exchange data, leading to automation and efficiency in various industries.

• Examples of IOT include smart homes, wearable devices, and industrial automation.

• AngularJS simplifies web development by providing a framework for building dynamic and responsive web applications.

• Examples of AngularJS include Google Analytics, PayPal, and T...read more

OOPs concepts are the fundamental principles of object-oriented programming.

• Encapsulation - binding data and functions together

• Inheritance - creating new classes from existing ones

• Polymorphism - ability of objects to take on many forms

• Abstraction - hiding implementation details

• Example: A car is an object that encapsulates data like speed and functions like accelerate and brake

• Example: A child class can inherit properties and methods from a parent class

• Example: A shape class c...read more

Spring Boot simplifies Spring framework development by providing auto-configuration, embedded servers, and production-ready features.

• Spring Boot provides auto-configuration which reduces the need for manual configuration, making development faster and easier.

• It includes embedded servers like Tomcat, Jetty, or Undertow, eliminating the need for deploying applications on external servers.

• Spring Boot offers production-ready features such as metrics, health checks, and externaliz...read more

For loop is used to iterate over a block of code multiple times based on a condition.

• Used to execute a block of code multiple times

• Iterates over a sequence of values

• Can be used with arrays, lists, or ranges

• Example: for(int i=0; i<5; i++) { //code block }

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

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: The ability for objects to be treated as instances of their parent class or their own class.

• Abstraction: Hidin...read more

Java is not considered a pure OOP language because it supports primitive data types and allows for procedural programming.

• Java supports primitive data types like int, double, and boolean which are not objects.

• Java allows for procedural programming with features like static methods and variables.

• In pure OOP languages like Smalltalk, everything is an object and there are no primitive data types or procedural features.

OOPs is a programming paradigm based on the concept of objects. ML is a subset of AI that enables machines to learn from data.

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

• Encapsulation is the process of hiding implementation details from the user.

• Inheritance allows a class to inherit properties and methods from another class.

• Polymorphism allows objects to take on multiple forms or behaviors.

• Abstraction is the process of hiding complex implem...read more

ML stands for Machine Learning, a subset of artificial intelligence that focuses on the development of algorithms and models that allow computers to learn from and make predictions or decisions based on data.

• ML involves training algorithms to recognize patterns in data and make decisions or predictions without being explicitly programmed.

• Common techniques in ML include supervised learning, unsupervised learning, and reinforcement learning.

• Examples of ML applications include r...read more

Arrays have a fixed size, while lists can dynamically grow and shrink.

• Arrays have a fixed size, while lists can dynamically grow and shrink.

• Arrays can only store elements of the same data type, while lists can store different data types.

• Arrays are accessed by index, while lists are accessed by iterators or pointers.

• Examples: Array - ['apple', 'banana', 'cherry'], List - ['apple', 5, true]

Collections in Java are pre-built data structures that allow storing and manipulating groups of objects.

• Collections provide a set of interfaces and classes to work with data structures like lists, sets, maps, etc.

• They offer various methods to add, remove, search, sort, and iterate over elements in the collection.

• Examples of collections include ArrayList, HashSet, TreeMap, etc.

• Collections framework is part of the Java API and is widely used in Java programming.

• It helps in writ...read more

C++ is a compiled language while Java is an interpreted language.

• C++ is faster and more efficient than Java.

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

• C++ supports multiple inheritance while Java only supports single inheritance.

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

• Java has a larger standard library than C++.

• C++ is commonly used for system programming and game development while Java is commonly used for web and mo...read more

I would like to see improvements in the website's user interface, search functionality, and mobile responsiveness.

• Enhance user interface with modern design elements and intuitive navigation

• Improve search functionality by implementing filters, sorting options, and predictive search

• Optimize website for mobile devices to ensure seamless user experience on all screen sizes

I am expecting a competitive salary based on industry standards and my qualifications.

• Research industry standards for Associate Software Engineer salaries

• Consider my qualifications, experience, and skills when determining salary expectations

• Be prepared to negotiate based on the company's offer and benefits package

I am using these frameworks in my project to increase efficiency, reduce development time, and ensure code quality.

• Frameworks provide pre-built components and libraries that can be easily integrated into the project

• They help in standardizing the codebase and following best practices

• Frameworks often come with built-in security features and updates, reducing the risk of vulnerabilities

• Using frameworks can also improve scalability and maintainability of the project

• For example, I...read more

The salary of 5.5 LPA is offered to candidates who are clear super coders.

• Demonstrate exceptional coding skills to qualify as a clear super coder.

• Show proficiency in various programming languages and problem-solving abilities.

• Possess a strong understanding of data structures and algorithms.

• Provide examples of successful projects or coding challenges completed.

• Highlight any relevant certifications or achievements in the field of software engineering.

COBOL is a high-level programming language used primarily for business applications.

• COBOL stands for Common Business-Oriented Language.

• It was designed in 1959 by CODASYL and is still widely used in legacy systems.

• COBOL programs are divided into four divisions: Identification, Environment, Data, and Procedure.

• It uses English-like syntax and is known for its readability and self-documenting code.

• Example: DISPLAY 'Hello, World!'

Use a subquery to find the second highest number in SQL

• Use a subquery to select the maximum number excluding the highest number

• Order the numbers in descending order and limit the result to the second row

Method overloading in Java allows multiple methods with the same name but different parameters.

• Method overloading is achieved by having methods with the same name but different parameters in a class.

• The compiler determines which method to call based on the number and type of arguments passed.

• Example: void print(int num) and void print(String str) are overloaded methods with different parameters.

Water pollution is a serious environmental issue caused by the release of harmful substances into water bodies.

• Water pollution is mainly caused by industrial waste, agricultural runoff, and improper disposal of chemicals and plastics.

• It leads to the contamination of drinking water sources, harming aquatic life, and disrupting ecosystems.

• Examples of water pollutants include oil spills, pesticides, heavy metals, and sewage.

• Efforts to combat water pollution include implementing ...read more

Object-oriented programming paradigm focusing on objects and classes.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (class).

• Inheritance: Ability of a class to inherit properties and behavior from another class.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation details and showing only the necessary features.

I prefer Java for its platform independence, strong community support, and extensive libraries.

• Platform independence allows Java code to run on any device with a Java Virtual Machine (JVM)

• Strong community support ensures quick resolution of issues and access to resources

• Extensive libraries provide pre-built solutions for common programming tasks

• Java is widely used in enterprise applications, web development, and mobile development

Answer the question as prompted by the chatbot

• Listen carefully to the chatbot's prompt

• Repeat the sentence as accurately as possible

• Provide a clear and concise response to the question

The impact of artificial intelligence on society

• AI has revolutionized various industries such as healthcare, finance, and transportation

• Ethical concerns surrounding AI, such as job displacement and privacy issues

• Potential benefits of AI, such as improved efficiency and decision-making

• Examples like self-driving cars, virtual assistants, and medical diagnosis systems

Types of joins include inner join, outer join (left, right, full), cross join, and self join.

• Inner join: Returns rows when there is a match in both tables

• Outer join: Returns all rows from one table and matching rows from the other table

• Cross join: Returns the Cartesian product of the two tables

• Self join: Joins a table to itself

C++ is an extension of C with additional features like classes and inheritance.

• C++ supports object-oriented programming concepts like classes and inheritance, while C does not.

• C++ has a more extensive standard library compared to C.

• C++ allows function overloading and templates, which are not available in C.

• C++ supports exception handling, while C does not have built-in support for it.

Kubernetes (k8s) is an open-source container orchestration platform that automates the deployment, scaling, and management of containerized applications.

• Kubernetes follows a master-slave architecture where the master node controls the cluster and the worker nodes run the containers.

• It uses etcd for storing configuration data, API server for communication, scheduler for assigning workloads, and controller manager for maintaining desired state.

• Kubernetes allows for horizontal s...read more

A linked list is a data structure consisting of nodes where each node points to the next node in the sequence.

• Consists of nodes connected by pointers

• Each node contains data and a reference to the next node

• Can be singly linked (each node points to the next) or doubly linked (each node points to the next and previous)

Garbage collection is a process in programming where the system automatically reclaims memory occupied by objects that are no longer in use.

• Garbage collection helps in managing memory efficiently by automatically deallocating memory that is no longer needed.

• It reduces the risk of memory leaks and helps in preventing bugs related to manual memory management.

• Examples of programming languages with garbage collection include Java, C#, and Python.

In Java, 'static' keyword is used to create class-level variables and methods that can be accessed without creating an instance of the class.

• Static variables are shared among all instances of a class.

• Static methods can be called without creating an instance of the class.

• Static blocks are used to initialize static variables.

• Static variables are initialized only once, at the start of the program execution.

• Example: public class MyClass { static int count = 0; }

Turbines are used to convert kinetic energy into mechanical energy. There are various types of turbines such as steam, gas, and hydraulic.

• Turbines are used in power generation, aviation, and marine propulsion.

• Steam turbines are used in thermal power plants to generate electricity.

• Gas turbines are used in aircraft engines and power plants.

• Hydraulic turbines are used in hydroelectric power plants.

• Wind turbines are used to generate electricity from wind energy.

• Turbines can be cl...read more

OOPs concepts are fundamental principles of object-oriented programming like Inheritance, Polymorphism, Encapsulation, and Abstraction.

• Inheritance: Allows a class to inherit properties and behavior from another class.

• Polymorphism: Allows objects to be treated as instances of their parent class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Abstraction: Hides the complex implementation details and only shows the necessary features.

I have experience working with technologies such as Java, Python, SQL, HTML, CSS, JavaScript, and Git in my projects.

• Java

• Python

• SQL

• HTML

• CSS

• JavaScript

• Git

Dependency injection is a design pattern where components are given their dependencies rather than creating them internally.

• Allows for easier testing by providing mock dependencies

• Promotes loose coupling between components

• Improves code reusability and maintainability

• Examples: Constructor injection, Setter injection, Interface injection

AWS is a cloud computing platform provided by Amazon, while DevOps is a software development methodology that combines software development with IT operations.

• AWS (Amazon Web Services) is a cloud computing platform that offers a wide range of services such as computing power, storage, databases, and more.

• DevOps is a software development methodology that focuses on collaboration, communication, automation, and integration between software developers and IT operations professio...read more

To swap two variables, use a temporary variable to store one value before swapping them.

• Create a temporary variable to store one of the values

• Assign the first variable to the temporary variable

• Assign the second variable to the first variable

• Assign the temporary variable to the second variable

I am a dedicated and passionate software engineer with experience in Java, Python, and web development.

• Experienced in Java, Python, and web development technologies

• Strong problem-solving skills

• Excellent communication and teamwork abilities

Pointers are variables that store memory addresses of other variables or functions.

• Pointers are used to access and manipulate memory directly.

• They are commonly used in programming languages like C and C++.

• Example: int *ptr; // declaring a pointer to an integer variable

The 4 pillars of OOP are Inheritance, Encapsulation, Abstraction, and Polymorphism.

• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Abstraction: Hiding the complex implementation details and showing only the necessary features of an object.

• Polymorphism: Ability of an object to take on many forms.

Threading in Python allows for concurrent execution of multiple tasks within a single process.

• Threading in Python is achieved using the 'threading' module.

• Threads are lightweight processes that share the same memory space.

• Threads can be created by subclassing the 'Thread' class and implementing the 'run' method.

• Python's Global Interpreter Lock (GIL) limits the effectiveness of threading for CPU-bound tasks, but it is still useful for I/O-bound tasks.

• Example: Creating and star...read more

The candidate is asked to repeat sentences spoken by an AI voice.

• Listen carefully to the sentences spoken by the AI voice.

• Repeat the sentences accurately and clearly.

• Pay attention to pronunciation and intonation.

• Ask for clarification if needed.

Operating systems are software that manage computer hardware and software resources.

• Windows

• MacOS

• Linux

• iOS

• Android