group chat app in java

group chat app in java

@@ -0,0 +1,104 @@
+import java.net.*;
+import java.io.*;
+import java.util.*;
+public class GroupChat
+{
+	private static final String TERMINATE = "Exit";
+	static String name;
+	static volatile boolean finished = false;
+	public static void main(String[] args)
+	{
+		if (args.length != 2)
+			System.out.println("Two arguments required: <multicast-host> <port-number>");
+		else
+		{
+			try
+			{
+				InetAddress group = InetAddress.getByName(args[0]);
+				int port = Integer.parseInt(args[1]);
+				Scanner sc = new Scanner(System.in);
+				System.out.print("Enter your name: ");
+				name = sc.nextLine();
+				MulticastSocket socket = new MulticastSocket(port);
+
+				// Since we are deploying
+				socket.setTimeToLive(0);
+				//this on localhost only (For a subnet set it as 1)
+
+				socket.joinGroup(group);
+				Thread t = new Thread(new
+				ReadThread(socket,group,port));
+
+				// Spawn a thread for reading messages
+				t.start();
+
+				// sent to the current group
+				System.out.println("Start typing messages...\n");
+				while(true)
+				{
+					String message;
+					message = sc.nextLine();
+					if(message.equalsIgnoreCase(GroupChat.TERMINATE))
+					{
+						finished = true;
+						socket.leaveGroup(group);
+						socket.close();
+						break;
+					}
+					message = name + ": " + message;
+					byte[] buffer = message.getBytes();
+					DatagramPacket datagram = new
+					DatagramPacket(buffer,buffer.length,group,port);
+					socket.send(datagram);
+				}
+			}
+			catch(SocketException se)
+			{
+				System.out.println("Error creating socket");
+				se.printStackTrace();
+			}
+			catch(IOException ie)
+			{
+				System.out.println("Error reading/writing from/to socket");
+				ie.printStackTrace();
+			}
+		}
+	}
+}
+class ReadThread implements Runnable
+{
+	private MulticastSocket socket;
+	private InetAddress group;
+	private int port;
+	private static final int MAX_LEN = 1000;
+	ReadThread(MulticastSocket socket,InetAddress group,int port)
+	{
+		this.socket = socket;
+		this.group = group;
+		this.port = port;
+	}
+
+	@Override
+	public void run()
+	{
+		while(!GroupChat.finished)
+		{
+				byte[] buffer = new byte[ReadThread.MAX_LEN];
+				DatagramPacket datagram = new
+				DatagramPacket(buffer,buffer.length,group,port);
+				String message;
+			try
+			{
+				socket.receive(datagram);
+				message = new
+				String(buffer,0,datagram.getLength(),"UTF-8");
+				if(!message.startsWith(GroupChat.name))
+					System.out.println(message);
+			}
+			catch(IOException e)
+			{
+				System.out.println("Socket closed!");
+			}
+		}
+	}
+}