Fiserv Technical Lead Interview Questions and Answers

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

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

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

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.

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

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

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