Multi-Threaded Chat System 💬

A real-time chat application built using Java Sockets. This project features a client-server architecture capable of handling multiple simultaneous users with private messaging, blocking capabilities, and colored terminal UI.

Features

• Multi-Client Support: Handle many users at once using a thread-per-client model.
• Private Messaging: Send direct messages to specific users.
• User Blocking: Feature to ignore messages from specific participants.
• File Transfer Basic functionality of sending files to server.

Concepts Used

• Networking: TCP/IP Sockets, Input/Output Streams, and Port Binding.
• Concurrency: Multi-threading (Runnable), volatile variables.
• Synchronization: Thread-safe collections (SynchronizedSet) and synchronized blocks for race-condition prevention.
• Protocol Design: Custom command parsing and state management.

⌨️ List of Commands

Command	Action
/list	Show all online users
/msg <user> <text>	Send a private message
/msgall <text>	Broadcast message to everyone
/block <user>	Ignore a specific user
/unblock <user>	Resume seeing messages from a user
/help	Show command menu
/exit	Safely disconnect from server
@ <filename>	Sends and store files in server directory

How to Run

1. Compile the files:

   javac *.java

2. Run the server:

   java ChatServer <port_no>

3. Run the clients in seperate terminals:

   java ChatClient localhost <port_no>