💬 Chat App with Socket Programming (Java)

🔗 GitHub Repository:
https://github.com/vyawaha/java-chat-app-socket-programming.git

A real-time client-server chat application built using Java Socket Programming that allows multiple users to communicate simultaneously through TCP sockets.

The project demonstrates practical implementation of:

• Client-server architecture
• TCP socket communication
• Multithreading
• Real-time message exchange
• Public broadcasting
• Private messaging
• User management
• Chat history logging

---

📌 Project Overview

Modern applications such as messaging platforms, multiplayer games, customer support systems, collaboration tools, and notification systems rely heavily on real-time communication.

This project implements the fundamental networking concepts behind these systems by creating a centralized Java chat server where multiple clients can connect, communicate, and exchange messages in real time.

---

🔗 Project Information

Category	Details
Project Name	Chat App with Socket Programming
Language	Java
Project Type	Networking / Backend Application
Communication	TCP Socket Programming
Architecture	Client-Server Architecture
Concurrency	Multithreading
Storage	File Based Chat Logging
Repository	https://github.com/vyawaha/java-chat-app-socket-programming.git

---

🎯 Problem Statement

Design and develop a real-time chat application where:

• Multiple clients can connect to one server
• Users can send messages simultaneously
• Messages are delivered instantly
• Users can communicate privately
• Server manages client connections
• Chat activity is stored for future reference

---

🚀 Features

Core Features

✅ TCP socket based communication
✅ Client-server architecture
✅ Multiple client support
✅ Real-time message exchange
✅ Username identification
✅ Join notification
✅ Leave notification
✅ Public message broadcasting
✅ Private messaging
✅ Chat history logging
✅ Graceful client disconnect
✅ Exception handling

---

🏗️ System Architecture

             Client 1
                |
                |
             Socket
                |
                |
Client 2 ---- Java Chat Server ---- Client 3
                |
                |
        Client Handler Threads
                |
                |
        Message Broadcasting
                |
                |
        Chat History Logger

---

🔄 Working Flow

Client Starts

      ↓

Connects to Server using Socket

      ↓

Server Accepts Connection

      ↓

Client Handler Thread Created

      ↓

User Enters Username

      ↓

Messages Sent To Server

      ↓

Server Processes Message

      ↓

Broadcast / Private Delivery

      ↓

Message Logged

---

🛠️ Technologies Used

Technology	Purpose
Java	Programming Language
Socket API	Network Communication
ServerSocket	Server Connection Handling
Thread	Concurrent Client Handling
BufferedReader	Reading Input
PrintWriter	Sending Output
File Handling	Chat Logging
Git/GitHub	Version Control

---

📚 Java Concepts Used

Socket

Used for communication between client and server.

ServerSocket

Used by the server to listen for incoming client connections.

Threads

Each client connection runs independently using a separate thread.

Collections

ArrayList is used to maintain active connected clients.

Synchronization

Used to safely access shared client data.

Exception Handling

Handles network failures and unexpected disconnections.

---

📂 Project Structure

java-chat-app-socket-programming
│
├── src
│   │
│   ├── server
│   │   ├── ChatServer.java
│   │   └── ClientHandler.java
│   │
│   ├── client
│   │   └── ChatClient.java
│   │
│   └── common
│       └── ChatLogger.java
│
├── logs
│   └── chat_history.txt
│
├── screenshots
│
├── docs
│   └── Testing_Report.md
│
├── README.md
├── LICENSE
└── .gitignore

---

▶️ How To Run The Project

Requirements

Install:

• Java JDK 17 or above
• Git
• VS Code / IntelliJ IDEA / Eclipse

Check Java:

java -version

---

Compile Project

From project root:

javac -d out src\common\*.java src\server\*.java src\client\*.java

---

Start Server

Open Terminal 1:

java -cp out server.ChatServer

Output:

==============================
 Java Chat Server
==============================

Server started successfully.
Listening on port : 5000
Waiting for clients...

---

Start Client 1

Open Terminal 2:

java -cp out client.ChatClient

Username:

Alice

---

Start Client 2

Open Terminal 3:

java -cp out client.ChatClient

Username:

Bob

---

Start Client 3

Open Terminal 4:

java -cp out client.ChatClient

Username:

Charlie

---

💬 Chat Commands

Public Message

Type:

Hello everyone

Output:

Alice: Hello everyone

---

Private Message

Format:

@username message

Example:

@Bob Hello Bob

Only Bob receives:

[Private] Alice: Hello Bob

---

📝 Chat Logging

All messages are stored in:

logs/chat_history.txt

Example:

Alice joined the chat

Bob joined the chat

Alice: Hello everyone

[Private] Alice: Hello Bob

Bob left the chat

---

🎥 Live Demo / Execution Flow

Demo Steps

1. Start Java Chat Server

java -cp out server.ChatServer

2. Connect multiple clients:

Alice
Bob
Charlie

3. Test communication:

• Send public messages
• Send private messages
• Disconnect users
• Verify notifications
• Check chat history

Expected Behavior

Server:

Alice joined the chat
Bob joined the chat

Alice: Hello Bob

[Private] Alice: Hi Bob

Bob left the chat

Client:

Alice: Hello everyone

[Private] Alice: Hi Bob

Chat log:

logs/chat_history.txt

---

🧪 Testing

The project was tested with:

Test Case	Result
Server startup	✅ PASS
Client connection	✅ PASS
Multiple clients	✅ PASS
Message broadcasting	✅ PASS
Private messaging	✅ PASS
User disconnect	✅ PASS
Chat logging	✅ PASS
Exception handling	✅ PASS

---

📸 Project Screenshots

Phase 1 - Project Structure

Complete project folder organization.

Phase 9 - Server Running and Client Communication

Multiple users communicating through Java socket server.

Phase 9 - Chat History Logging

Stored messages generated by the application.

Phase 11 - Multiple Client Testing

Testing communication between multiple users.

Phase 11 - Private Messaging

Testing user-to-user private communication.

---

🌍 Industry Relevance

This project demonstrates concepts used in:

• Messaging applications
• Multiplayer games
• Customer support systems
• Collaboration platforms
• Real-time notification systems
• Distributed applications

The same networking principles are used in large-scale backend systems.

---

🔮 Future Improvements

Possible enhancements:

• Java Swing / JavaFX GUI
• User authentication
• Database integration
• Multiple chat rooms
• File sharing
• Message encryption
• Cloud deployment
• Online/offline status
• End-to-end encryption

---

🎓 Learning Outcomes

Through this project, I learned:

✅ TCP/IP communication
✅ Socket programming
✅ Multithreaded server design
✅ Client-server architecture
✅ Real-time communication systems
✅ Network exception handling
✅ GitHub project management

---

🏷️ GitHub Topics

java
socket-programming
tcp
networking
client-server
multithreading
threads
backend
java-project
console-application
oop
computer-networks
chat-application
server
github-portfolio

---

👨‍💻 Author

Muktai Vyawahare

Computer Science Engineering Student

GitHub Portfolio Project

---

⭐ Support

If you like this project, consider giving it a ⭐ on GitHub.

Explore the implementation of Java networking, socket programming, and multithreaded backend systems.