import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;

public class EchoClient {

	public static void main(String[] args) throws Exception {
		if( args.length != 2 ) {
			System.out.println("usage: java EchoClient hostname port");
			System.exit(0);
		}

		// Prepare address and port of the server
		String server = args[0] ;
		int port = Integer.parseInt( args[1] );
		InetAddress srvAddress = InetAddress.getByName( server );
		
		String request;

		// Create a helper scanner to read complete lines from standard input
		try(Scanner in = new Scanner( System.in )) {
		   // Read the "request" from the standard input
		   System.out.print("Say what? " );
		   request = in.nextLine(); 
		}
		
		// Prepare the socket to exchange datagrams
		try( DatagramSocket socket = new DatagramSocket() ) {
		  
		  // Convert the request string into bytes
		  byte[] reqData = request.getBytes();
		         
		  // Prepare the datagram filling in the contents and address in one go
		  DatagramPacket echoReq = new DatagramPacket( reqData, reqData.length, srvAddress, port );

		  socket.send( echoReq );

		  // Prepare an empty datagram to receive the reply
		  byte[] buffer = new byte[65536] ;
		  DatagramPacket echoReply = new DatagramPacket( buffer, buffer.length );
		        
		  socket.receive( echoReply );
		       
		  // Create a string from the contents of the datagram
		  String echoedMsg = new String( echoReply.getData(), 0, echoReply.getLength() ) ;
		  System.out.printf("Got echo: \"%s\"\n", echoedMsg ) ;
		}
	}

}