200+ Junior Software Developer Interview Questions and Answers

Multithreading allows multiple threads to run concurrently, while OOP is a programming paradigm based on the concept of objects.

• Multithreading allows for parallel execution of multiple threads within a single process.

• OOP is a programming paradigm that uses objects to represent data and methods to manipulate that data.

• In multithreading, each thread has its own stack and runs independently, while in OOP, objects encapsulate data and behavior.

• Example of multithreading: running a...read more

Many to many vs has and belongs to many association, and explanation of polymorphic association.

• Many to many association involves a join table to connect two models with a many-to-many relationship.

• Has and belongs to many association is a simpler version of many to many, where the join table is hidden.

• Polymorphic association allows a model to belong to more than one other model, using a single association.

• Example: Many to many - Students and Courses, HABTM - Users and Roles, ...read more

Inheritance is a concept in object-oriented programming where a class inherits properties and behaviors from another class.

• Inheritance allows for code reusability and promotes a hierarchical relationship between classes.

• Example: Class B inherits from Class A, gaining access to its attributes and methods.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• Example: A method that can take an object of a parent class as an argument can...read more

Input and output functions in C language are used to interact with the user and the external environment.

• Input functions in C include scanf() for reading input from the user and getchar() for reading a single character.

• Output functions in C include printf() for displaying output to the user and putchar() for displaying a single character.

• File input and output functions in C include fopen(), fclose(), fread(), and fwrite() for reading from and writing to files.

Client-side validation is the process of validating user input on the client-side before submitting it to the server.

• It is performed using JavaScript or HTML5 attributes.

• It helps to reduce server load and improve user experience.

• It can be easily bypassed, so server-side validation is also necessary.

• Examples include checking for required fields, email format, and password strength.

I approach problem solving in software development by breaking down the problem, researching, and testing solutions.

• Break down the problem into smaller, manageable tasks

• Research and gather information about the problem domain

• Brainstorm and evaluate potential solutions

• Implement and test the chosen solution

• Iterate and refine the solution based on feedback

Sensitive information in a web application can be secured through encryption, access controls, secure coding practices, and regular security audits.

• Encrypt sensitive data at rest and in transit using strong encryption algorithms.

• Implement access controls to restrict unauthorized access to sensitive information.

• Follow secure coding practices to prevent common vulnerabilities like SQL injection and cross-site scripting.

• Regularly conduct security audits and vulnerability assessm...read more

Angular Modules are containers for a group of related components, directives, and services. Data binding is a way to synchronize data between the component and the view.

• Angular Modules help organize an application into cohesive blocks of functionality.

• Data binding in Angular allows the synchronization of data between the component and the view.

• Types of data binding in Angular are one-way binding ({{}}), two-way binding ([()]), and event binding (()).

In MVC, we can redirect to a different page using the RedirectToAction method.

• Use the RedirectToAction method in the controller action method

• Pass the action name and controller name as parameters to the method

• Optionally, pass route values as a parameter to the method

• Example: return RedirectToAction("Index", "Home");

OOPs is a programming paradigm based on the concept of objects, with features like inheritance, polymorphism, interfaces, and abstract classes.

• Inheritance allows a class to inherit properties and behavior from another class. For example, a 'Car' class can inherit from a 'Vehicle' class.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass. For example, a 'Shape' superclass can have subclasses like 'Circle' and 'Square'.

• Interfaces def...read more

Object-oriented programming (OOP) is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating objects that interact with each other to solve problems

• It involves concepts like classes, objects, inheritance, polymorphism, and encapsulation

• Example: In a banking system, you can have classes like Account, Customer, and Transaction with their respective objects

String is a sequence of characters, while StringBuilder is a mutable sequence of characters used for manipulating strings efficiently.

• String is immutable in Java, meaning once created, it cannot be changed.

• StringBuilder is mutable and allows for efficient manipulation of strings.

• String concatenation using '+' operator creates a new string object each time, while StringBuilder's append method modifies the existing object.

• Use StringBuilder when frequent modifications to strings...read more

ASP.NET uses various validations like RequiredFieldValidator, RangeValidator, RegularExpressionValidator, etc.

• RequiredFieldValidator - Ensures a field is not left blank

• RangeValidator - Validates if a value falls within a specified range

• RegularExpressionValidator - Validates input based on a specified pattern

Abstraction, inheritance, encapsulation, and polymorphism are the four pillars of object-oriented programming.

• Abstraction is the process of hiding complex implementation details and showing only the necessary information to the user.

• Inheritance is the mechanism of creating a new class from an existing class, inheriting all the properties and methods of the parent class.

• Encapsulation is the practice of keeping the data and methods that operate on the data together in a single ...read more

Yes, multiple catch blocks can be used with one try block to handle different types of exceptions.

• Multiple catch blocks can be used to handle different types of exceptions thrown within the try block.

• Each catch block can specify a different type of exception to catch and handle.

• The catch blocks are evaluated in order, so the first catch block that matches the thrown exception type will be executed.

• If no catch block matches the thrown exception type, the exception will propaga...read more

The project is a web-based inventory management system for a retail store.

• Designed E-R Diagram with entities like Product, Supplier, Customer, Order, and Inventory

• Database design includes tables for each entity with appropriate relationships and attributes

• Used SQL to create tables, define constraints, and write queries for data retrieval and manipulation

Delays are interruptions or setbacks in a process. They can be avoided by proper planning and communication.

• Identify potential delays and plan for them

• Communicate effectively with team members and stakeholders

• Use project management tools to track progress and identify issues

• Address issues promptly to prevent further delays

• Continuously evaluate and improve processes to minimize delays

Key concepts of OOP include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (class).

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

• Polymorphism: The ability for objects of different classes to respond to the same method call.

• Abstraction: Hiding the complex implementation details and showing only the necessary features to the outside world.

Variables used in Constructors

• Instance variables

• Local variables

• Parameters

Promises in JavaScript are used to handle asynchronous operations and avoid callback hell.

• Promises represent a value that may not be available yet but will be resolved at some point in the future.

• They have three states: pending, fulfilled, or rejected.

• Promises can be chained using .then() and .catch() methods.

• They can also be used with async/await syntax.

• Example: new Promise((resolve, reject) => {...}).then(result => {...}).catch(error => {...})

Method overloading is having multiple methods in the same class with the same name but different parameters, while method overriding is redefining a method in a subclass with the same name and parameters as in the superclass.

• Method overloading is resolved at compile time based on the method signature, while method overriding is resolved at runtime based on the object type.

• Method overloading is used to provide multiple methods with the same name but different functionality, wh...read more

OOPS concepts refer to Object-Oriented Programming concepts such as inheritance, encapsulation, polymorphism, and abstraction. They are used to create modular, reusable, and maintainable code.

• Inheritance: Allows a class to inherit properties and behavior from another class. Example: Parent class 'Animal' and child class 'Dog'.

• Encapsulation: Bundling data and methods that operate on the data into a single unit. Example: Class 'Car' with private variables and public methods.

• Pol...read more

To check for JWT in Postman, use the 'Authorization' tab and select 'Bearer Token' type.

• In Postman, go to the 'Authorization' tab of your request.

• Select 'Bearer Token' from the dropdown menu.

• Enter the JWT token in the provided field.

• Send the request to authenticate using the JWT.

Use encryption to hide network data from inspection.

• Implement SSL/TLS to encrypt data transmitted over the network

• Use VPNs to create secure tunnels for data transmission

• Utilize firewalls to restrict access to network data

• Implement secure coding practices to prevent data leakage

• Use encryption algorithms like AES to protect sensitive data

Interface defines only method signatures while abstract class can have method implementations.

• Interface cannot have method implementations, only method signatures

• Abstract class can have method implementations along with abstract methods

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

• Interfaces are used to achieve multiple inheritance in Java

• Abstract classes can have constructors while interfaces cannot

Quick sort and Merge sort are popular sorting algorithms used to efficiently sort arrays of elements.

• Quick sort: Divide and conquer algorithm, picks a pivot element and partitions the array around the pivot. Recursively sorts subarrays.

• Merge sort: Divide and conquer algorithm, divides the array into two halves, recursively sorts the halves, and then merges them back together.

• Example: Quick sort - [3, 6, 8, 10, 1, 2, 1], Merge sort - [7, 2, 4, 1, 5, 3]

Implementation of a linked list in code format

• Define a Node class with data and next pointer

• Create LinkedList class with methods like insert, delete, search

• Handle edge cases like empty list, inserting at beginning/end

Promises in JavaScript are used to handle asynchronous operations and provide a way to handle the result or error of an asynchronous operation.

• Use .then() method to handle the resolved value of a promise

• Use .catch() method to handle any errors that occur during the promise execution

• Use Promise.all() to handle multiple promises concurrently

• Use async/await to work with promises in a more synchronous way

Create a form to input data and display it below the form.

• Create an HTML form with input fields for data entry

• Use JavaScript to capture the form data on submission

• Display the captured data below the form using DOM manipulation

Triggers are database operations that automatically execute in response to certain events on a table or view.

• DML Triggers: Execute on data manipulation events like INSERT, UPDATE, DELETE. Example: A trigger that logs changes to a table.

• DDL Triggers: Execute on data definition language events like CREATE, ALTER, DROP. Example: A trigger that prevents dropping a table.

• LOGON Triggers: Execute when a user logs into the database. Example: A trigger that restricts access based on u...read more

Python has two major versions - Python 2 and Python 3. Python 3 has multiple subversions like 3.6, 3.7, 3.8, etc.

• Python has two major versions - Python 2 and Python 3

• Python 3 has multiple subversions like 3.6, 3.7, 3.8, etc.

• The latest version of Python 3 is 3.9 as of 2021

Guido van Rossum created Python in 1989 while working at CWI in the Netherlands.

• Guido van Rossum created Python in 1989.

• He was working at CWI (Centrum Wiskunde & Informatica) in the Netherlands at the time.

• Python was released as open source in 1991.

Dependency injection is a design pattern where components are given their dependencies rather than creating them internally.

• Allows for easier testing by mocking dependencies

• Promotes loose coupling between components

• Can be implemented using constructor injection, setter injection, or interface injection

IIFE stands for Immediately Invoked Function Expression. It is a function that is executed as soon as it is defined.

• IIFE is enclosed in parentheses () to make it an expression.

• It is followed by another set of parentheses () to invoke the function immediately.

• It is commonly used to create a private scope for variables and functions.

• Example: (function() { console.log('Hello World!'); })();

Java is an object-oriented language while C is a procedural language.

• Java is platform-independent while C is platform-dependent.

• Java has automatic garbage collection while C requires manual memory management.

• Java has built-in support for multithreading while C requires external libraries.

• Java has a larger standard library compared to C.

• Java is more secure than C due to its strong type checking and exception handling.

• C is faster than Java in terms of execution speed.

• C is commo...read more

OOP is a programming paradigm that uses objects to represent real-world entities. Project details can be explained using OOP concepts.

• OOP is based on the concept of classes and objects

• Classes are like blueprints for objects

• Objects have properties and methods

• Encapsulation, inheritance, and polymorphism are key OOP concepts

• Example: A car class can have properties like make, model, and year, and methods like start and stop

A programme to check if a given string is a palindrome.

• Create a function that takes a string as input.

• Convert the string to lowercase and remove any non-alphanumeric characters.

• Reverse the string and compare it to the original string.

• If they are the same, return true. Otherwise, return false.

A thread is a lightweight process that can run concurrently with other threads. Multithreading is the ability to have multiple threads in a single process.

• Threads share the same memory space as the parent process

• Multithreading can improve performance by allowing multiple tasks to be executed simultaneously

• Synchronization is important to prevent race conditions and ensure thread safety

• Examples of multithreading include web servers handling multiple requests and video games ren...read more

Different types of queues include linear, circular, priority, and double-ended.

• Linear queue follows a First-In-First-Out (FIFO) order.

• Circular queue is similar to linear queue but the last element points to the first element.

• Priority queue assigns a priority to each element and dequeues the highest priority element first.

• Double-ended queue allows insertion and deletion at both ends.

Swapping array elements and reversing string using recursion.

• Create a recursive function that swaps the first and last elements of the array until the middle is reached.

• Create a recursive function that reverses the string by swapping the first and last characters until the middle is reached.

• Use a temporary variable to store the value of the element being swapped.

• Make sure to handle edge cases such as empty arrays or strings.

Project 1 is a web application for managing inventory and sales data using Java, Spring Boot, and MySQL.

• Tech stack used: Java, Spring Boot, MySQL

• Implemented SQL queries for retrieving and updating data

• Utilized inheritance in Java for creating reusable code

• Performed joins in SQL to fetch data from multiple tables

Header files contain declarations of functions, variables, and constants used in a program.

• Header files are included in source code files using #include directive.

• They help in organizing code by separating declarations from implementation.

• Common header files in C/C++ include , , and .

OOPs stands for Object-Oriented Programming and its pillars are Inheritance, Encapsulation, Abstraction, and Polymorphism.

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

• Encapsulation restricts access to certain components within a class, protecting the data.

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

• Polymorphism allows objects to be treated as instances of their parent class, enabling flexibilit...read more

Asynchronous tasks in JavaScript allow for non-blocking operations, improving performance and user experience.

• Use callbacks, promises, or async/await to handle asynchronous tasks

• Callbacks: Functions passed as arguments to be executed once the task is complete

• Promises: Objects representing the eventual completion or failure of an asynchronous operation

• Async/await: Syntactic sugar for promises, making asynchronous code look synchronous

• Example: Fetching data from an API, handlin...read more

Angular Life Cycle Hooks are methods that allow you to tap into the lifecycle of a component or directive.

• ngOnChanges - called when an input property changes

• ngOnInit - called once the component is initialized

• ngDoCheck - called during every change detection run

• ngAfterContentInit - called after content (ng-content) has been projected into the component

• ngAfterContentChecked - called after every check of the projected content

• ngAfterViewInit - called after the component's view has...read more

To find the mean of an array, add all the elements and divide by the number of elements.

• Add all the elements of the array

• Divide the sum by the number of elements

• Return the mean value