Visa Lead Engineer Interview Questions and Answers

Q1. What is dependency injection?
Ans. 
Dependency injection is a design pattern in which components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by mocking dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: Instead of a class creating an instance of another...read more
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Q2. What is app.use in .net core?
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app.use in .NET Core is used to add middleware to the request pipeline.
• app.use is a method used in ASP.NET Core to add middleware components to the request pipeline.

• Middleware components are software components that are executed in the request pipeline to handle requests and responses.

• Middleware components can perform tasks such as authentication, logging, error handling, and more.

• Example: app.use(new MiddlewareCompone
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Q3. What is difference between Interface and abstract class?
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Interface is a contract that defines the methods a class must implement, while abstract class can have both abstract and concrete methods.
• Interface cannot have any implementation, while abstract class can have both abstract and concrete methods.

• A class can implement multiple interfaces but can only inherit from one abstract class.

• Interfaces are used to achieve multiple inheritance in Java, while abstract classes are us...read more
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Q4. Boxing Unboxing
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Q5. ArrayList and List
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Q6. Can abstract class instantiated?
Ans. 
No, abstract classes cannot be instantiated.
• Abstract classes are meant to be inherited and extended by other classes.

• Attempting to instantiate an abstract class will result in a compilation error.

• Abstract classes can have abstract methods that must be implemented by the subclass.
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Q7. How to optimize react application?
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Optimizing a React application involves code splitting, lazy loading, minimizing bundle size, using memoization, and optimizing render performance.
• Implement code splitting to load only necessary code for each route or component.

• Utilize lazy loading to defer loading of non-essential components until they are needed.

• Minimize bundle size by removing unused code, optimizing images, and using tree shaking.

• Use memoization te...read more
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Q8. Props destructuring?
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Q9. Parent child component communication in react?
Ans. 
Parent child component communication in React involves passing data from parent to child components and triggering events from child to parent components.
• Use props to pass data from parent to child components

• Use callback functions to trigger events from child to parent components

• Context API can be used for passing data to deeply nested components
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Q10. What is useRef, useMemo, useCallback?
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useRef is used to persist a value across renders, useMemo is used to memoize expensive calculations, useCallback is used to memoize functions.
• useRef is commonly used to access DOM elements or persist values between renders.

• useMemo is used to memoize expensive calculations to avoid re-computation.

• useCallback is used to memoize functions to prevent unnecessary re-renders.

• Example: useRef can be used to store a reference t...read more
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1. One question regarding the MaxPartitions for a given array, if array is [4, 3, 2, 6 , 5, 10, 9] => upon sorting it appears like [2, 3, 4, 5, 6, 7, 9, 10] ..Max slices are [2,3,4] [5, 6] [9, 10] so slice count is 3

2. Another one Max integer upon removal 5 digit

Q1. Two technical rounds happened 1. One technical round : It was all about the Architecture , Design patterns on Microservices like CircuitBreaker etc and also security concepts, 2. Another technical round...read more
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