Enfin Technologies Full Stack Software Developer Interview Questions and Answers

Oops concept, basic javascript and react js coding question

Q1. React js and asp.net basic interview questions
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Q1. What is concurrent hashmap
Ans. 
ConcurrentHashMap is a thread-safe implementation of the HashMap class in Java.
• ConcurrentHashMap allows multiple threads to read and write to the map concurrently without causing any data corruption.

• It achieves thread-safety by dividing the map into segments, each of which can be locked independently.

• ConcurrentHashMap is more efficient than using synchronized collections for concurrent access.

• Example: ConcurrentHashMap...read more
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Q2. How is dependency injection different from dependency inversion
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Dependency injection is a design pattern where dependencies are provided to a class from the outside, while dependency inversion is a principle that states high-level modules should not depend on low-level modules, but both should depend on abstractions.
• Dependency injection is a technique to achieve dependency inversion.

• Dependency injection involves providing dependencies to a class from the outside, typically through ...read more
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Q3. If I add 2 same attribute values for a object to a set...will I see 2 objects in the set, if yes what changes you make to the code to insert unique objects to a set
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No, you will not see 2 objects in the set. To insert unique objects to a set, you can override the equals() and hashCode() methods in the object class.
• In a set, each element must be unique based on the equals() method. If you add 2 objects with the same attribute values, only one will be stored in the set.

• To ensure uniqueness, override the equals() and hashCode() methods in the object class. This will define how object...read more
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Q4. What is serialisation, externalisation, serializable
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Serialisation is the process of converting an object into a format that can be easily stored or transmitted. Externalisation is a way to customize the serialization process. Serializable is an interface in Java that allows objects to be serialized.
• Serialisation is the process of converting an object into a format that can be easily stored or transmitted

• Externalisation is a way to customize the serialization process

• Seri...read more
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Q5. Write a Generic method to add string or integer to List or List
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Create a generic method to add string or integer to List<Integer> or List<String>
• Create a generic method that takes a List and an element as input

• Use Java generics to specify the type of List and element

• Check the type of List and element, then add the element to the List
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Q1. What is closures in JS ?
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Closures in JavaScript are functions that have access to variables from their outer scope, even after the outer function has finished executing.
• Closures are created when a function is defined inside another function.

• The inner function has access to the outer function's variables, parameters, and even the outer function's return value.

• Closures are useful for creating private variables and data encapsulation.

• They can be ...read more
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Q2. Diff props and state ?
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Props and state are both used in React to manage and pass data, but they have different purposes and behaviors.
• Props are read-only and passed from parent components to child components.

• State is mutable and managed within a component.

• Props are used to pass data from a parent component to a child component.

• State is used to manage and update data within a component.

• Props are passed as attributes to a component in JSX.

• Stat...read more
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Q3. How to optimise the performance ?
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Performance optimization involves identifying and resolving bottlenecks to improve the efficiency of software.
• Identify and analyze performance bottlenecks

• Optimize algorithms and data structures

• Improve database performance through indexing and query optimization

• Use caching techniques to reduce database and network calls

• Minimize network latency by optimizing network requests

• Optimize front-end code by reducing DOM manipul...read more
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Q4. Diff between class based or function based component ?
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Class-based components are ES6 classes that extend React.Component, while function-based components are functions that return JSX.
• Class-based components are more feature-rich and have access to lifecycle methods.

• Function-based components are simpler and easier to read and test.

• Class-based components can have state and use lifecycle methods like componentDidMount and componentDidUpdate.

• Function-based components can use ...read more
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Q5. What is es6 features ?
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ES6 (ECMAScript 2015) introduced several new features to JavaScript, enhancing its functionality and making it more efficient.
• Arrow functions: concise syntax for writing functions

• Let and const: block-scoped variables

• Template literals: easier string interpolation

• Destructuring assignment: extracting values from arrays or objects

• Spread syntax: expanding elements in arrays or objects

• Classes: syntactical sugar for creating ...read more
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Q1. Diff. Between promise and observable
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Promise is a one-time event while Observable can emit multiple values over time.
• Promise is used for asynchronous operations that will return a single value or an error.

• Observable is used for asynchronous operations that can return multiple values over time.

• Promise can be in one of three states: pending, fulfilled, or rejected.

• Observable can emit values, errors, and completion events.

• Promise can be converted to an Obser...read more
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Q2. Lifecycle hooks in angular
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Angular lifecycle hooks are methods that get called at specific stages of a component's lifecycle.
• ngOnInit() - called after the component is initialized

• ngOnChanges() - called when the component's input properties change

• ngOnDestroy() - called just before the component is destroyed

• ngAfterViewInit() - called after the component's view has been initialized

• ngAfterContentInit() - called after the component's content has been
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Q3. Jwt security implementation in angular
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Jwt security implementation in Angular
• Install angular-jwt package

• Create an auth service to handle token storage and retrieval

• Add an HttpInterceptor to attach the token to outgoing requests

• Use guards to protect routes based on authentication status
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Q1. How do you do version upgrades
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I use version control systems like Git to manage code changes and upgrades.
• I create a new branch for the upgrade to isolate changes from the main codebase.

• I test the upgrade in the new branch to ensure compatibility and functionality.

• I merge the upgraded code back into the main branch once testing is successful.

• I document the changes made during the upgrade process for future reference.
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Q1. Can we make applications using on C# code
Ans. 
Yes, applications can be made using C# code.
• C# is a versatile programming language commonly used for developing applications.

• C# can be used to create web applications, desktop applications, mobile apps, and more.

• Popular frameworks like .NET and Xamarin support C# for application development.
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Basic questions number, logical reasoning, apptitude, values, circle etc

Q1. Introduction to your self, which language do preference, Java, oops concepts
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Q2. Opp concepts , Java, HTML, CSS, javascript, PHP, python, SQL language questions basic knowledge
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Q3. Do you have completed any project
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Q4. What is method overloading
Ans. 
Method overloading is when multiple methods in a class have the same name but different parameters.
• Allows multiple methods with the same name but different parameters to be defined in a class

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

• Example: having multiple 'calculate' methods in a class with different parameter types like int, double, etc.
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Technical related questions

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Q2. MySQL and mongodb
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