import java.net.* ;
import java.util.* ;

public class EchoClient {

	static final int ECHOPORT = 8000;
	static final String LOCALSERVER = "localhost";

	public static void main(String[] args) throws Exception {
		if( args.length > 1 ) {
			System.err.printf("usage: java EchoClient [server_computer] \n") ;
			System.exit(0);
		}
		// Get server IP address and create an UDP socket
		String server = LOCALSERVER;
		if( args.length == 1) server = args[0];
		InetAddress serverAddress = InetAddress.getByName( server ) ;
		DatagramSocket socket = new DatagramSocket();
		// Read a message from the input console
		Scanner in = new Scanner( System.in );
		System.out.printf("Echo client - please type a messsage: ") ;
		String request = in.nextLine();
		// Prepare a datagram to send to the server in a compact way
		// send it, wait for the reply, print it
		DatagramPacket datagram = new DatagramPacket( request.getBytes(), 
		    request.length(), serverAddress, ECHOPORT ) ;
		socket.send( datagram );
		socket.receive( datagram );
		socket.close() ;
		System.out.printf("Got: \"%s\"\n", 
			new String( datagram.getData(), 0, datagram.getLength() ) ) ;
	} // main
}