import java.io.*;
import java.net.*;

class UDPClient
{
    public static void main(String args[]) throws Exception
    {
        int portaServer = 6789;
        InetAddress IPServer = InetAddress.getByName("localhost");

        byte[] bufferOUT = new byte[1024];
        byte[] bufferIN = new byte[1024];
        BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

        // Creo socket client
        DatagramSocket clientSocket = new DatagramSocket();

        // Invio notifica di connessione
        bufferOUT = "conn!".getBytes();
        DatagramPacket sendPacket = new DatagramPacket(bufferOUT, bufferOUT.length, IPServer, portaServer);
        clientSocket.send(sendPacket);

        System.out.println("Client pronto - inserisci un dato da inviare: ");

        // Acquisizione da tastiera
        String daSpedire = input.readLine();
        bufferOUT = daSpedire.getBytes();

        // Invio pacchetto
        sendPacket = new DatagramPacket(bufferOUT, bufferOUT.length, IPServer, portaServer);
        clientSocket.send(sendPacket);

        // Ricevo pacchetto
        DatagramPacket receivePacket = new DatagramPacket(bufferIN, bufferIN.length);
        clientSocket.receive(receivePacket);
        String ricevuto = new String(receivePacket.getData());

        // Analizzo pacchetto
        int numCaratteri = receivePacket.getLength();
        ricevuto = ricevuto.substring(0, numCaratteri); //elimina i caratteri in eccesso
        System.out.println("dal SERVER:" + ricevuto);

        // Chiusura connessione
        clientSocket.close();
    }
}