import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.MulticastSocket;


public class DatagramExample {
	public static final int BUFFER_SIZE = 1000;
	
	public static void main(String[] args) {
		try {
			BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
			System.out.println("Enter a port to receive on.");
			int recvPort = Integer.parseInt(in.readLine());
			final DatagramSocket socket = new DatagramSocket(recvPort);
			
			Thread thread = new Thread(new Runnable() {
				public void run() {
					byte[] bytes = new byte[BUFFER_SIZE];
					DatagramPacket recvPacket = new DatagramPacket(bytes, BUFFER_SIZE);
					while (true) {
						try {
							socket.receive(recvPacket);
							String content = new String(bytes, 0, recvPacket.getLength());
							System.out.println("Content: " + content);
						} catch (Exception e) {
							e.printStackTrace();
						}
						
					}
				}
			});
			thread.start();
			
			int count = 1;
			while (true) {
				System.out.println("Enter a port to send to.");
				int sendPort = Integer.parseInt(in.readLine());
				String message = "Message " + count++;
				byte[] messageBytes = message.getBytes();
				DatagramPacket sendPacket = new DatagramPacket(messageBytes, messageBytes.length, InetAddress.getLocalHost(), sendPort);
				socket.send(sendPacket);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		
		
	}
}