EchoClient

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

public class EchoClient {
  public static void main(String[] args) throws IOException {

    Socket echoSocket = null;
    PrintWriter out = null;
    BufferedReader in = null;

    // get hostname

    BufferedReader stdIn = new
      BufferedReader(new InputStreamReader(System.in));
    String userInput;

    System.out.print ("Enter hostname:  ");
    userInput = stdIn.readLine();

    try {
      echoSocket = new Socket(userInput, 9999);
      out = new PrintWriter(echoSocket.getOutputStream(), true);
      in = new BufferedReader
    (new InputStreamReader(echoSocket.getInputStream()));
    } catch (UnknownHostException e) {
      System.err.println("Don't know about host: " + userInput + ".");
      System.exit(1);
    } catch (IOException e) {
      System.err.println("Couldn't get I/O for the connection to: " +
             userInput + ".");
      System.exit(1);
    }

    while ((userInput = stdIn.readLine()) != null) {
      out.println(userInput);
      System.out.println("echo: " + in.readLine());
    }

    out.close();
    in.close();
    stdIn.close();
    echoSocket.close();
  }
}