HashMap

A HashMap is a data structure that stores key-value pairs using hashing for fast access, insertion and deletion. Keys are unique and each maps to exactly one value. It offers average O(1) time complexity for basic operations and is widely used for efficient lookups, caching and data mapping in applications.

What are the differences between a Java HashMap and a Hashtable?

How can I iterate over a HashMap in Java?

Popular Topics

Array

An array is a systematic arrangement of similar objects, usually in rows and columns.

Two Pointes

It is a tech to solve coding problems.

Query

In databases, a query is a request to retrieve, insert, update or delete data. Written in SQL (Structured Query Language), queries can be simple, like fetching all rows from a table, or complex, involving joins, conditions and aggregations. They are essential for interacting with and managing database information efficiently.

Git

Git is an open-source distributed version control system.

Interview

A structured conversation where one participant asks questions and the other provides answers of those questions.

String

String is a data type used in most of the programming language. String is a sequence of characters and can contain letters, spaces , symbols ,numbers etc. commonly used for text, though sometimes for arbitrary data.

DSA

DSA (Data Structures and Algorithms) is a fundamental concept in computer science that focuses on efficiently storing, organizing and processing data. Data structures like arrays, linked lists, stacks and trees manage data, while algorithms provide step-by-step solutions to problems. Mastering DSA is essential for writing optimized, scalable and high-performance code.

Coding Problems

Practice Coding Problems to boost your skill.

Database

A database is an organized collection of data. It is the collection of schemas, tables, queries, reports, views, and other objects. The data are typically organized to model aspects of reality in a way that supports processes requiring information. Use this tag if you have questions about designing a database.

Software Design

Software design is the process of planning and structuring a software system’s architecture, components, interfaces, and data flow to meet functional and non-functional requirements. It ensures scalability, maintainability and performance. Key approaches include modular design, object-oriented design and architectural patterns like MVC and microservices for efficient, reliable software development.

Most Popular Tools

Explore our top online tools including a blank page for notes, a QR code generator, word counter and collaborative editor. These free, easy-to-use utilities help you write, analyze, share and organize content faster. Perfect for developers, creators and students to streamline everyday digital tasks efficiently.

Blank Page

Create a blank canvas for your ideas, notes or sketches. Use this tool for rough work and jotting down your thoughts

QR Code Generator

A QR Code Generator is a tool that instantly converts text, URLs or other data into a scannable QR code. Users can create custom QR codes for websites, contact info or messages. It's commonly used for quick access, sharing and printing without needing a backend or complex setup.

Word Counter

Perform various string operations like counting characters, words or letters.

Collaborative Editor

Collab Editor is a powerful, free-to-use online platform that lets you collaborate in real-time. Whether you re working on documents, brainstorming idea, or discussing projects etc