🏷️ Online Auction System

A console-based Online Auction System built in Java that simulates real-time bidding with multiple users, auction timers, and leaderboard ranking.

This project demonstrates core Java concepts such as OOP, Multithreading, Collections, and Auction Bidding Logic.

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🚀 Features

• 👤 Multiple bidder support
• 🔐 Admin login to create auctions
• ⏱️ Real-time countdown timer for auctions
• 💰 Dynamic bidding system
• 🏆 Bidder leaderboard ranking
• 📊 Highest bid tracking
• 📦 Auction winner display
• 🧠 Thread-based auction closing
• 📚 Clean object-oriented project structure

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🧱 Project Structure

OnlineAuctionSystem
│
├── User.java
├── Admin.java
├── Bid.java
├── Item.java
├── AuctionManager.java
├── CountdownTimer.java
└── Main.java

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🛠️ Technologies Used

• Java
• OOP (Object-Oriented Programming)
• Multithreading
• Java Collections (ArrayList)
• Comparator Sorting
• Console-based UI

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⚙️ How It Works

1. Admin logs in to the system.
2. Admin creates a new auction item.
3. Auction timer starts automatically.
4. Users place bids on the item.
5. Highest bid is updated in real-time.
6. When the timer ends, the auction closes.
7. The highest bidder wins the item.
8. Leaderboard shows top bidders.

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▶️ How to Run

1. Clone the repository

git clone https://github.com/yogeshkumarsaini/online-auction-system-java.git

2. Open the project in IntelliJ / Eclipse / VS Code

3. Compile the files

javac *.java

4. Run the program

java Main