50+ Junior Developer Interview Questions and Answers

I am shifting to software because of my passion for coding and the potential for growth in the industry.

• Passionate about coding and software development

• Believe software industry has more potential for growth

• Enjoy problem-solving and creating solutions through software

• Interested in exploring new technologies and advancements in software

The question covers various topics related to database management, SQL, and object-oriented programming concepts.

• Truncate is a DDL command used to delete all records from a table, while delete is a DML command used to remove specific records.

• Primary key uniquely identifies each record in a table, while a unique key ensures that all values in a column are unique.

• Composite key is a combination of multiple columns that uniquely identify a record in a table.

• Foreign key establishe...read more

Find the first repeating number from an unsorted array.

• Iterate through the array and keep track of seen numbers using a hash set.

• If a number is already in the set, it is the first repeating number.

• Return the first repeating number or -1 if no repeating number is found.

The task is to find the number of unique characters in a given string.

• Create an empty array to store unique characters.

• Iterate through each character in the string.

• If the character is not already present in the array, add it.

• Finally, return the length of the array as the number of unique characters.

Callback functions are functions passed as arguments to other functions and executed later when the parent function is called.

• Callback functions are used for asynchronous programming.

• They are commonly used in event listeners and AJAX requests.

• Callback functions can be anonymous or named functions.

• They can also be used to pass data between functions.

My favorite coding language is Python because of its simplicity and versatility.

• Python has a simple syntax which makes it easy to learn and use.

• It is a versatile language that can be used for web development, data analysis, machine learning, and more.

• Python has a large and supportive community with a vast number of libraries and frameworks available.

• It is also cross-platform, meaning that code written on one operating system can be easily run on another.

• Python is constantly e...read more

A framework is a pre-written code that provides a structure for building software applications.

• A framework provides a set of rules and guidelines for developers to follow

• It includes pre-written code for common tasks, such as handling user input or database interactions

• Frameworks can be specific to a programming language or platform, such as React for JavaScript or Django for Python

• Examples of popular frameworks include Angular, Laravel, and Ruby on Rails

Regular functions are defined using the function keyword, while arrow functions use the => syntax.

• Arrow functions have a shorter syntax than regular functions.

• Arrow functions do not have their own 'this' keyword.

• Arrow functions cannot be used as constructors.

• Regular functions can be used as methods on objects, while arrow functions cannot.

• Arrow functions are always anonymous, while regular functions can be named or anonymous.

Separate service providers in Flutter help to decouple the business logic from the UI layer, making the code more modular and maintainable.

• Separate service providers help in following the single responsibility principle by separating the UI logic from the business logic.

• They make the code more modular and easier to maintain by allowing for easier testing and reusability of code.

• Service providers can be used to handle network requests, database operations, and other business l...read more

Hash functions in Java are used to convert an input into a fixed-size string of bytes, typically for data retrieval and security purposes.

• Hash functions take an input (or 'key') and return a fixed-size string of bytes, known as the hash value.

• In Java, the hashCode() method is commonly used to generate hash codes for objects.

• Hash functions are used in data structures like HashMap to efficiently store and retrieve key-value pairs.

Footer in HTML, anchor tag details, and CSS syntax and types.

• Footer in HTML is used to display information at the bottom of a webpage.

• Anchor tag in HTML is used to create hyperlinks. Example: Link

• CSS syntax includes selectors, properties, and values. Example: h1 { color: blue; }

• Types of CSS include inline, internal, and external stylesheets.

Stack is Last In First Out (LIFO) data structure, while Queue is First In First Out (FIFO) data structure.

• Stack follows LIFO principle, where the last element added is the first one to be removed.

• Queue follows FIFO principle, where the first element added is the first one to be removed.

• Stack operations include push (add element) and pop (remove element).

• Queue operations include enqueue (add element) and dequeue (remove element).

Yes, I have experience coding for face recognition using OpenCV and Python.

• I have worked on projects involving face detection, recognition, and tracking.

• I am familiar with OpenCV libraries and have used them to implement face recognition algorithms.

• I have experience with Python programming language and its libraries for image processing.

• I have also worked with deep learning frameworks like TensorFlow and Keras for face recognition tasks.

Yes, I have experience in Python, AI, and ML.

• I have worked on various projects using Python for data analysis and automation.

• I have also implemented machine learning algorithms using libraries like scikit-learn and TensorFlow.

• I have experience in natural language processing and computer vision using AI techniques.

• I have worked on projects like sentiment analysis, image classification, and recommendation systems.

Feature branching in Github is a practice of creating a separate branch for each new feature or task to isolate changes.

• Feature branching helps in keeping the main branch clean and stable.

• Developers can work on different features simultaneously without interfering with each other's code.

• Once the feature is complete, it can be merged back into the main branch through a pull request.

• Example: Creating a 'login-feature' branch to work on implementing a new login functionality.

Node.js is a runtime environment that allows you to run JavaScript on the server side.

• Node.js is built on Chrome's V8 JavaScript engine.

• It is used for building scalable network applications.

• Node.js uses an event-driven, non-blocking I/O model.

• It is commonly used for building web servers and APIs.

• Example: Creating a simple web server using Node.js.

Object-oriented programming concepts in C#

• Encapsulation: bundling data and methods into a single unit

• Inheritance: creating new classes from existing ones

• Polymorphism: using a single interface to represent different types

• Abstraction: hiding unnecessary details and exposing only essential features

• Example: Creating a class 'Car' with properties like 'color' and methods like 'startEngine'

• Example: Inheriting from a base class 'Animal' to create derived classes like 'Dog' and 'Cat'

Object Oriented Programming Concepts involve encapsulation, inheritance, and polymorphism.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (class). Example: class Car with properties like make, model, and methods like start(), stop().

• Inheritance: Allows a class to inherit properties and methods from another class. Example: class SUV extends Car, inheriting properties and methods from the Car class.

• Polymorphism: Ability of objects to take on...read more

Hash function in Java is a function that converts an input (or 'key') into a unique numerical value, which is used to index data in hash tables.

• Hash functions are used to quickly retrieve data in hash tables by converting keys into unique numerical values.

• In Java, hash functions are commonly used in HashMap and HashSet to store and retrieve key-value pairs efficiently.

• Examples of hash functions in Java include hashCode() method in Object class and MessageDigest class for cryp...read more

I was rated highly in C# language due to my strong understanding of object-oriented programming principles and experience with various C# frameworks.

• Strong understanding of object-oriented programming principles

• Experience with various C# frameworks such as .NET Core, ASP.NET, and Xamarin

• Ability to write clean and efficient code

• Familiarity with C# features like LINQ, async/await, and generics

Object-oriented programming is a programming paradigm based on the concept of objects, which can contain data and code.

• Objects are instances of classes, which define the structure and behavior of the objects.

• Encapsulation, inheritance, and polymorphism are key principles of OOP.

• Example: In a banking system, a 'Customer' class can have attributes like name and account balance, and methods like deposit and withdraw.

Known languages refer to programming languages while software refers to applications or programs built using those languages.

• Known languages are used to write code and give instructions to computers.

• Software is the end product that is created using known languages.

• Examples of known languages include Java, Python, C++, while examples of software include Microsoft Word, Photoshop, Chrome.

Abstraction can be achieved by hiding unnecessary details and focusing on essential features.

• Identify the essential features of the system

• Hide unnecessary details by using abstract classes or interfaces

• Encapsulate the implementation details

• Use inheritance and polymorphism to achieve abstraction

• Example: A car's essential features are its ability to move, steer, and stop. The engine's internal workings are unnecessary details that can be hidden.

• Example: An abstract class 'Vehic...read more

To post a form in PHP, use the method attribute in the form tag to specify 'POST' and set the action attribute to the PHP file that will process the form data.

• Create a form in HTML with method='POST' and action='process.php'

• Use input elements within the form to collect user data

• In the 'process.php' file, use $_POST to access the form data submitted

To upload a file in PHP, use the built-in function move_uploaded_file().

• Create a form with enctype='multipart/form-data'

• Use $_FILES['file']['name'] to get the name of the file

• Use $_FILES['file']['tmp_name'] to get the temporary location of the file

• Use move_uploaded_file() to move the file to the desired location

HTTP process in Flutter involves making network requests to fetch data from servers.

• Use packages like http or dio to make HTTP requests in Flutter.

• Send requests to a server using methods like GET, POST, PUT, DELETE.

• Handle responses using Future and async/await.

• Example: Making a GET request to fetch data from an API.

In Flutter, models are used to represent data and manage state within an application.

• Models are classes that define the structure of data in an application.

• They are used to store and manage data, as well as handle business logic.

• Models can be used to update the UI when data changes, using the setState() method.

• Example: class User { String name; int age; }

• Example: class Product { String name; double price; }

The 'using' keyword in C# is used to define a scope in which an object is created and used, and automatically disposes of the object when the scope is exited.

• Used for managing resources like files, database connections, etc.

• Ensures that the object is disposed of properly even if an exception occurs.

• Example: using (FileStream fileStream = new FileStream("example.txt", FileMode.Open)) { // code }

Data structures are ways of organizing and storing data in a computer so that it can be accessed and used efficiently.

• Data structures define how data is stored, accessed, and manipulated in a computer program.

• Examples include arrays, linked lists, stacks, queues, trees, and graphs.

• Choosing the right data structure is crucial for optimizing performance and memory usage in software development.

A responsive website is a site that is designed to adapt to different screen sizes and devices for optimal viewing experience.

• Uses flexible grids and layouts

• Utilizes media queries to adjust styles based on screen size

• Ensures content is easily readable and accessible on all devices

Optimizing SQL queries involves using indexes, minimizing data retrieval, avoiding unnecessary joins, and optimizing query structure.

• Use indexes on columns frequently used in WHERE clauses

• Minimize data retrieval by selecting only necessary columns

• Avoid unnecessary joins by using EXISTS or IN clauses instead

• Optimize query structure by avoiding subqueries and using appropriate join types

Closure is a function that has access to its outer function's variables, even after the outer function has returned.

• Closure is created when a function is defined inside another function.

• The inner function has access to the outer function's variables and parameters.

• The inner function can access the outer function's variables even after the outer function has returned.

• Closures can be used to create private variables and methods in JavaScript.

The 'this' keyword refers to the current object in which the code is being executed.

• The value of 'this' depends on how a function is called.

• In a global context, 'this' refers to the global object (window in a browser).

• In a function context, 'this' refers to the object that the function is a method of.

• In an event context, 'this' refers to the element that triggered the event.

• In a constructor function, 'this' refers to the object being created.

• Arrow functions do not have their ...read more

InnoDB is the default storage engine in MySQL.

• InnoDB is the default storage engine in MySQL since version 5.5.

• It supports transactions, foreign keys, and row-level locking.

• Other storage engines like MyISAM and MEMORY are also available.

Handled incident by identifying root cause, implementing solution, and documenting for future reference.

• Identify the root cause of the incident

• Implement a solution to resolve the incident

• Document the incident and solution for future reference

Padding is extra space added to the edges of an element, often used to create visual separation or alignment.

• Padding is used in CSS to control the spacing between the content and the border of an element.

• It can be specified in various units like pixels, percentages, or em.

• Padding is applied to all four sides of an element by default, but can be customized for individual sides using shorthand properties.

• Example: padding: 10px; or padding: 5px 10px 15px 20px; (top, right, botto...read more

PHP is a server-side scripting language used for web development.

• PHP stands for Hypertext Preprocessor.

• It is widely used for creating dynamic web pages.

• PHP code is embedded within HTML code.

• PHP can interact with databases like MySQL.

• Popular PHP frameworks include Laravel and Symfony.

Merge sort is a divide and conquer algorithm that divides the input array into two halves, sorts them separately, and then merges them back together in sorted order.

• Divide the input array into two halves

• Recursively sort each half

• Merge the sorted halves back together

A linked list is a data structure where each element points to the next element in the sequence.

• Consists of nodes connected by pointers

• Can be singly linked or doubly linked

• Allows for efficient insertion and deletion operations

ASP.NET life cycle is a series of events that occur during the processing of a web request.

• The life cycle starts when a request is made and ends when a response is sent back to the client.

• It includes events like Application_Start, Page_Init, Page_Load, Page_PreRender, and Page_Unload.

• During the life cycle, the page goes through various stages like initialization, loading, rendering, and unloading.

• Developers can use events and methods to customize the behavior of the page duri...read more

Loops are programming constructs that allow for the repeated execution of a block of code based on a condition.

• Loops help automate repetitive tasks in programming.

• Common types of loops include for, while, and do-while loops.

• Example: for loop in Python - for i in range(5): print(i)

LinkedList is better for frequent insertions and deletions, ArrayList is better for random access.

• LinkedList uses pointers to connect elements, ArrayList uses a dynamic array.

• LinkedList is slower for random access but faster for insertions and deletions.

• ArrayList is faster for random access but slower for insertions and deletions.

• Example: LinkedList is used in undo functionality where elements are frequently added and removed.

• Example: ArrayList is used in scenarios where rand...read more

Using Java 8, reverse an array of strings

• Use Arrays.stream() to convert the array to a stream

• Use Collections.reverse() to reverse the stream

• Use Collectors.toList() to convert the stream back to a list

Machine learning is a subset of AI that enables computers to learn and make decisions without explicit programming.

• Machine learning is a branch of artificial intelligence.

• It focuses on developing algorithms that allow computers to learn and improve from experience.

• Machine learning models can analyze large amounts of data to make predictions or decisions.

• Examples of machine learning include image recognition, natural language processing, and recommendation systems.

ES6 introduced new features to improve JavaScript syntax and functionality.

• Arrow functions for concise syntax

• Let and const for block-scoped variables

• Template literals for string interpolation

• Destructuring for easy object and array manipulation

• Default parameters for function arguments

• Spread and rest operators for easy array manipulation

• Classes for object-oriented programming

• Promises for asynchronous programming

• Modules for better code organization

OOPS Concepts in C# include inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance allows a class to inherit properties and behavior from another class.

• Encapsulation restricts access to class members and methods.

• Polymorphism allows objects to be treated as instances of their parent class.

• Abstraction hides the implementation details and only shows the necessary features.

Hash set stores unique elements only, while hash map stores key-value pairs.

• Hash set does not allow duplicate elements, while hash map allows duplicate values but not duplicate keys.

• In Java, HashSet and HashMap are implementations of these data structures.

• Example: HashSet can be used to store a collection of unique usernames, while HashMap can be used to store username-password pairs.