50+ Junior Software Developer Interview Questions and Answers for Freshers

The player who picks the last coin loses the game.

• The game starts with n coins.

• Each player can pick 1 to 5 coins in one turn.

• The player who picks the last coin loses the game.

• Determine if the given n coins will result in a win or loss for the starting player.

Answering questions about golang, job switch, salary expectations, and location comfort.

• Golang is a programming language developed by Google, known for its simplicity and efficiency.

• I have used golang in my previous job to develop a microservices architecture for a web application.

• I am looking to switch jobs to gain new experiences, challenges, and opportunities for growth.

• My salary expectation is based on my skills, experience, and market standards.

• I am comfortable working i...read more

Reverse a linked list using recursion, handling all corner cases

• Create a recursive function that takes the head of the linked list as input

• Base case: if the head is null or the list contains only one node, return the head

• Recursively call the function with the next node as input and set its next pointer to the current node

• Set the current node's next pointer to null and return the new head

Write a function to check whether a binary tree is a sub-tree of another binary tree (Check for all corner cases)

• Create a function that traverses both trees and compares them

• Check if the root of the second tree matches any node in the first tree

• Handle cases where one or both trees are empty

• Handle cases where the trees have different structures

Count the number of 0's in a sorted array of 0's and 1's.

• Iterative solution: Traverse the array and count the number of 0's.

• Recursive solution: Divide the array into two halves and recursively count the number of 0's in each half.

• Binary search can also be used to find the first occurrence of 0 and then count the number of 0's after that index.

Binary Search Tree is a data structure where each node has at most two children, with left child smaller and right child larger. Time complexity is O(log n) for search, insert, and delete operations.

• Nodes have at most two children - left child is smaller, right child is larger

• Search, insert, and delete operations have time complexity of O(log n)

• Example: In a BST, if we search for a value, we can eliminate half of the remaining nodes at each step

Array is a fixed-size data structure while linked list is a dynamic data structure. ArrayList and LinkedList are implementations of List interface in Java.

• Array is a contiguous block of memory with fixed size, while linked list is a collection of nodes where each node points to the next node.

• ArrayList in Java is implemented using an array, which can dynamically resize itself. LinkedList is implemented using nodes with references to the next and previous nodes.

• Arrays are faste...read more

A list of technical questions for a Junior Software Developer position.

• Super is a keyword in Java used to refer to the parent class.

• Java is platform independent due to its bytecode being able to run on any platform with a JVM.

• Multiple Inheritance is the ability for a class to inherit from multiple parent classes.

• The diamond problem occurs when a class inherits from two classes that have a common ancestor, causing ambiguity.

• Normalization is the process of organizing data in a ...read more

Given a number n, find the number just greater than n using same digits as that of n

• Convert the number to a string and sort the digits in ascending order

• Starting from the rightmost digit, find the first digit that is smaller than the digit to its right

• Swap this digit with the smallest digit to its right that is greater than it

• Sort the digits to the right of the swapped digit in ascending order

• Concatenate the digits to get the next greater number

Program to form a string with first character of all words in a given string.

• Split the string into an array of words

• Iterate through the array and extract the first character of each word

• Join the extracted characters to form the final string

A library is a collection of functions or classes that can be called by an external program, while a framework is a set of libraries that provide a structure for building applications.

• Library is used by the developer to perform specific tasks, while a framework dictates the overall structure of the application.

• Libraries are more flexible and allow developers to pick and choose which components to use, while frameworks have a more rigid structure.

• Examples of libraries include ...read more

Software development life-cycle is a process used to design, develop, test, and deploy software applications.

• SDLC consists of several phases such as planning, analysis, design, implementation, testing, and maintenance.

• Each phase has its own set of activities and deliverables to ensure the successful completion of the project.

• SDLC models include Waterfall, Agile, Scrum, and DevOps, each with its own approach to software development.

• The goal of SDLC is to produce high-quality s...read more

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

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

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

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

Lists are mutable, ordered collections of items, while tuples are immutable, ordered collections of items.

• Lists are denoted by square brackets [], while tuples are denoted by parentheses ().

• Lists can be modified after creation, while tuples cannot be modified.

• Lists are typically used for collections of similar items that may need to be changed, while tuples are used for fixed collections of items.

• Example: list_example = [1, 2, 3], tuple_example = (4, 5, 6)

Find a pair of integers in an array with the maximum product.

• Iterate through the array and keep track of the maximum and second maximum values.

• Consider negative numbers and zero.

• Time complexity: O(n)

Python is a high-level programming language used for web development, data analysis, artificial intelligence, and more.

• Web development using frameworks like Django and Flask

• Data analysis and visualization using libraries like Pandas and Matplotlib

• Artificial intelligence and machine learning using libraries like TensorFlow and Scikit-learn

• Scripting and automation tasks

• Game development using Pygame

• Desktop application development using PyQt and Tkinter

Calculate the sum of prime numbers.

• Iterate through numbers and check if each number is prime

• If a number is prime, add it to the sum

• Return the sum of prime numbers

Yes, Java technology is likely to be utilized in the future due to its popularity, versatility, and continuous updates.

• Java is a widely used programming language in various industries, including software development.

• Many companies rely on Java for their applications and systems, making it a valuable skill for developers.

• Java's strong community support and frequent updates ensure its relevance and longevity in the tech industry.

Abstract classes are classes that cannot be instantiated and can have both abstract and non-abstract methods. Interfaces are contracts that define the methods that a class must implement.

• Abstract classes can have constructors while interfaces cannot

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

• Abstract classes can have instance variables while interfaces cannot

• Interfaces can have default methods while abstract classes cannot

• An abstract ...read more

I am proficient in Java, Python, and JavaScript.

• Java

• Python

• JavaScript

Truncate removes all rows from a table, Delete removes specific rows, and Drop deletes the entire table structure.

• Truncate is a DDL command that removes all rows from a table but keeps the table structure intact.

• Delete is a DML command that removes specific rows based on a condition.

• Drop is a DDL command that deletes the entire table structure along with all its data.

• Truncate is faster than Delete as it does not log individual row deletions.

• Drop is irreversible and cannot be ...read more

HashMap is used for key-value pairs, ArrayList is used for dynamic arrays. Stream is used for processing collections.

• HashMap stores key-value pairs, allows fast retrieval based on keys.

• ArrayList stores elements in a dynamic array, allows fast access by index.

• Stream is used for processing collections in a functional style, supports operations like filter, map, reduce.

Polymorphism is the ability of a single function or method to operate on different types of data.

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

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: a superclass Animal with subclasses Dog and Cat. Both Dog and Cat can be treated as Animals.

Suitable code structure involves proper organization, readability, and maintainability.

• Use consistent naming conventions for variables, functions, and classes.

• Break down complex tasks into smaller, more manageable functions.

• Follow the SOLID principles to ensure code is modular and easy to modify.

• Use comments and documentation to explain the purpose and functionality of code.

• Consider the needs of future developers who may need to work with the code.

• Use version control to track...read more

HTML stands for Hypertext Markup Language. It is the standard markup language for creating web pages and web applications.

• HTML is used to structure content on the web.

• It consists of elements enclosed in tags, such as <p> for paragraphs.

• Attributes can be added to elements to provide additional information.

• HTML5 is the latest version of HTML, introducing new features like <video> and <canvas>.

• CSS is often used in conjunction with HTML to style web pages.

Java is a popular programming language used for developing software applications.

• Java is platform-independent, meaning it can run on any operating system.

• It has a large standard library with built-in functions and classes for common tasks.

• Java supports object-oriented programming, making it easier to organize and reuse code.

• It provides automatic memory management through garbage collection.

• Java is widely used in enterprise applications, web development, Android app developmen...read more

HashMap is a data structure in Java that stores key-value pairs.

• HashMap is part of the Java Collections framework.

• Keys in a HashMap must be unique.

• Values in a HashMap can be duplicated.

• Example: HashMap map = new HashMap<>();

• Example: map.put("John", 25);

Try catch block is used for error handling, while garbage collection is automatic memory management in programming.

• Try catch block is used to handle exceptions in code and prevent crashes.

• Garbage collection automatically manages memory by deallocating unused objects.

• Example: try { // code that may throw an exception } catch (Exception e) { // handle the exception }

• Example: Garbage collection in Java automatically deallocates memory for objects no longer in use.

Use a subquery to select the highest salary from the table

• Use a subquery to find the maximum salary in the table

• Select all columns from the table where the salary matches the maximum salary found in the subquery

Primary key is a unique identifier for a record in a database table.

• Primary key ensures data integrity and helps in faster data retrieval.

• It cannot have null or duplicate values.

• Examples of primary keys are social security number, email address, etc.

React is a JavaScript library for building user interfaces.

• Components are the building blocks of a React application

• Components can be class components or functional components

• Components can have state and props

• Components can be reused throughout the application

Sets, Lists, and Tuples are all data structures in Python with different characteristics and use cases.

• Sets are unordered collections of unique elements. Example: {1, 2, 3}

• Lists are ordered collections of elements that can be modified. Example: [1, 2, 3]

• Tuples are ordered collections of elements that cannot be modified. Example: (1, 2, 3)

Check if a number is a palindrome or not

• Convert the number to a string

• Reverse the string and compare with the original string

• If they are the same, the number is a palindrome

Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.

• Encapsulation helps in hiding the internal state of an object and only exposing necessary functionalities.

• It allows for better control over the data by preventing direct access from outside the class.

• Example: A car object encapsulates its properties like speed, fuel level, and methods like start, stop, accelerate.

• Example: A bank account object encapsulates its balance, accoun...read more

Yes, I am ready to shift to Gandhinagar.

• I am excited about the opportunity to work in Gandhinagar.

• I have researched the area and am comfortable with the location.

• I am willing to relocate and make the necessary arrangements.

• I am open to exploring the city and its culture.

JavaScript is a high-level, interpreted programming language used for creating interactive websites and web applications.

• JavaScript is commonly used for client-side web development.

• It can also be used for server-side development with Node.js.

• JavaScript allows for dynamic content, interactivity, and animations on websites.

• Examples include form validation, interactive maps, and dynamic page content.

React JS is a popular JavaScript library for building user interfaces.

• Allows for reusable components

• Virtual DOM for efficient updates

• Declarative syntax for easier development

OOPs stands for Object-Oriented Programming. It is a programming paradigm based on the concept of objects, which can contain data and code.

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

• It involves concepts like inheritance, encapsulation, polymorphism, and abstraction

• Examples of OOP languages include Java, C++, and Python

break, pass, and continue are control flow statements used in programming to alter the flow of execution.

• break: used to exit a loop or switch statement

• pass: not a keyword in most programming languages, but can be used as a placeholder for future code

• continue: used to skip the rest of the current iteration in a loop and start the next iteration

List is a data structure in Python that stores a collection of items in a specific order.

• Common methods/functions for lists in Python include append(), remove(), sort(), and index().

• Lists can contain different data types, such as strings, integers, and even other lists.

• Lists are mutable, meaning you can change the elements within a list after it has been created.