Coforge Senior Software Engineer Interview Questions and Answers

Q1. What are props and state?
Ans. 
Props are inputs to components, while state is a component's internal data that can change over time.
• Props (short for properties) are read-only and passed from parent to child components.

• State is mutable and managed within the component itself, allowing it to change over time.

• Example of props: <ChildComponent name='John' /> where 'name' is a prop.

• Example of state: this.setState({ count: this.state.count + 1 }) up...read more
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Q2. What is spread operator?
Ans. 
The spread operator expands iterable elements into individual elements, simplifying array and object manipulation in JavaScript.
• Syntax: The spread operator is represented by three dots (...).

• Usage with arrays: It can be used to create a new array by combining existing arrays. Example: const newArray = [...array1, ...array2];

• Usage with objects: It allows for shallow copying and merging of objects. Example: const newObje...read more
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Q3. How to optimize react?
Ans. 
Optimize React by minimizing re-renders, using memoization, and leveraging code-splitting techniques.
• Use React.memo to prevent unnecessary re-renders of functional components.

• Implement useCallback and useMemo hooks to memoize functions and values.

• Utilize React.lazy and Suspense for code-splitting to load components only when needed.

• Avoid inline functions in render methods to reduce re-creation on each render.

• Use the sh...read more
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Q4. Can we replce redux with react hooks?
Ans. 
React hooks can replace Redux for state management in simpler applications, but Redux offers more structure for complex states.
• React's useState and useReducer hooks can manage local state effectively.

• For global state, useContext combined with useReducer can mimic Redux functionality.

• Example: useReducer can handle complex state logic similar to Redux reducers.

• Redux provides middleware support (like redux-thunk) for asyn...read more
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Q5. What are new in ES6?
Ans. 
ES6 introduces significant improvements to JavaScript, enhancing syntax and functionality for developers.
• Arrow Functions: Shorter syntax for function expressions. Example: const add = (a, b) => a + b;

• Template Literals: Multi-line strings and string interpolation. Example: const greeting = `Hello, ${name}!`;

• Destructuring Assignment: Unpacking values from arrays or properties from objects. Example: const [x, y] = [1, ...read more
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Q6. What is default parameter in ES6?
Ans. 
Default parameters in ES6 allow functions to initialize parameters with default values if no argument is provided.
• Default parameters are defined in the function signature: `function multiply(a, b = 1) { return a * b; }`.

• If no value is passed for `b`, it defaults to `1`: `multiply(5)` returns `5`.

• Default parameters can be any expression, including function calls: `function greet(name = getDefaultName()) { ... }`.

• They ca...read more
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Q7. What are design principles?
Ans. 
Design principles are fundamental guidelines that inform and shape software architecture and design decisions.
• Separation of Concerns: Different functionalities should be separated into distinct sections, e.g., MVC architecture.

• Single Responsibility Principle: A class should have one reason to change, like a User class managing user data only.

• Open/Closed Principle: Software entities should be open for extension but clos...read more
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Q8. What is Liskov Substitution Principle?
Ans. 
Liskov Substitution Principle states that objects of a superclass should be replaceable with objects of a subclass without affecting functionality.
• Subtypes must be substitutable for their base types without altering the correctness of the program.

• Example: If 'Bird' is a superclass, 'Sparrow' and 'Penguin' should be subclasses that can replace 'Bird' without issues.

• Violating this principle can lead to unexpected behavio...read more
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Q9. What is Interface Segregation Principle?
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The Interface Segregation Principle advocates for creating smaller, specific interfaces rather than large, general-purpose ones.
• Clients should not be forced to depend on interfaces they do not use.

• Example: Instead of a single 'Animal' interface with methods like 'fly', 'swim', and 'walk', create separate interfaces like 'Flyable', 'Swimmable', and 'Walkable'.

• This reduces the impact of changes and promotes better code o...read more
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Q10. What is request delegate in ASP.net core?
Ans. 
A request delegate in ASP.NET Core handles HTTP requests and defines how to process them in middleware.
• Request delegates are functions that take an HttpContext and return a Task.

• They are used in middleware to process requests and responses.

• Example: app.Use(async (context, next) => { await next(); });

• Delegates can be composed to create a pipeline of request processing.

• They allow for separation of concerns in handling...read more
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Q1. Core Java concepts , multithreading
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Q2. Aws , 2 dsa easy level coding , 2 sql find max highest salary
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Q1. Technical discussion over how the microservices communicate internally.
Ans. 
Microservices communicate via APIs, messaging queues, and event-driven architectures for efficient data exchange and service coordination.
• RESTful APIs: Microservices expose endpoints for HTTP requests, e.g., a user service providing /users endpoint.

• gRPC: A high-performance RPC framework using Protocol Buffers, suitable for internal service communication.

• Message Queues: Services can communicate asynchronously using tool...read more
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Q2. Immutable class implementation
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An immutable class ensures that its instances cannot be modified after creation, promoting safety and simplicity.
• Use 'final' keyword for fields to prevent reassignment.

• Provide a constructor to initialize all fields.

• No setter methods should be present.

• Return copies of mutable objects instead of the original in getters.

• Example: A Point class with x and y coordinates.
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Q3. Singleton class implementation
Ans. 
A Singleton class ensures a class has only one instance and provides a global point of access to it.
• Use a private constructor to prevent instantiation from outside the class.

• Implement a static method to provide access to the single instance.

• Use lazy initialization to create the instance only when needed.

• Consider thread safety using synchronized methods or double-checked locking.
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Q1. What are distributes transactions and how these can be handled in microservices
Ans. 
Distributed transactions involve multiple systems coordinating to ensure data consistency across different services in a microservices architecture.
• Distributed transactions involve multiple services or databases working together to ensure data consistency.

• In microservices, handling distributed transactions can be challenging due to the decentralized nature of the architecture.

• One approach to handling distributed transa...read more
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Q2. Spring boot @Transactional annotation working
Ans. 
The @Transactional annotation in Spring Boot manages transaction boundaries for database operations.
• Defines the scope of a single database transaction.

• Automatically rolls back transactions on runtime exceptions.

• Can be applied at the method or class level.

• Example: @Transactional public void saveUser(User user) { userRepository.save(user); }

• Supports propagation behaviors like REQUIRED, REQUIRES_NEW, etc.
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Calculate the sum between two positive integers in an array.