10+ Cognizant Interview Questions and Answers

Sync API waits for a response before continuing, while Async API allows the program to continue executing without waiting for a response.

• Sync API is blocking and waits for a response before proceeding

• Async API is non-blocking and allows the program to continue executing while waiting for a response

• Sync microservice handles requests sequentially, while Async microservice can handle multiple requests concurrently

• Example of Sync API: REST API that waits for a response before ret...read more

Create a REST api to fetch user details using userId

• Create a GET endpoint /users/{userId} to fetch user details

• Use userId as a parameter in the endpoint

• Return user details in JSON format

• Handle errors for invalid userId

Create a global exception handler class for UserNotFound exception.

• Create a class that extends ExceptionHandler class

• Override the handleException method to handle UserNotFound exception

• Implement the logic to handle the exception, such as logging or returning a custom error message

SOLID principles and best coding practices are essential for creating maintainable and scalable software.

• S - Single Responsibility Principle: Each class should have only one responsibility.

• O - Open/Closed Principle: Classes should be open for extension but closed for modification.

• L - Liskov Substitution Principle: Subtypes should be substitutable for their base types.

• I - Interface Segregation Principle: Clients should not be forced to depend on interfaces they do not use.

• D - ...read more

Stream.map() transforms each element in a stream, while Stream.flatMap() transforms each element into a stream of values.

• map() applies a function to each element in a stream and returns a new stream with the transformed elements.

• flatMap() applies a function that returns a stream for each element in the original stream, then flattens the streams into a single stream of values.

• Example: map() - Stream.of(1, 2, 3).map(x -> x * 2) returns Stream.of(2, 4, 6).

• Example: flatMap() - St...read more

Print duplicate elements in an Array of strings

• Iterate through the array and use a HashMap to store frequency of each element

• Print elements with frequency greater than 1 as duplicates

IOC in Spring and DI offer flexibility, maintainability, and testability in software development.

• Promotes loose coupling between components

• Allows for easier unit testing and mocking

• Facilitates easier configuration and management of dependencies

• Enables better separation of concerns

• Promotes reusability of components

A top view of a binary tree shows the nodes visible from the top when looking down from the root node.

• The top view of a binary tree can be obtained by performing a level order traversal and keeping track of the horizontal distance of each node from the root.

• Nodes with the same horizontal distance are at the same level in the top view.

• Example: For the binary tree 1 -> 2 -> 3 -> 4 -> 5, the top view would be 1 -> 2 -> 3 -> 4 -> 5.

Spring IOC (Inversion of Control) is a design pattern where the control of object creation and lifecycle is shifted to a container.

• In Spring IOC, objects are created and managed by the Spring container.

• Types of Spring IOC include Constructor-based dependency injection and Setter-based dependency injection.

• Example: In Constructor-based dependency injection, dependencies are provided through the constructor of a class.

• Example: In Setter-based dependency injection, dependencies ...read more