Re: Help wiith input/output of jar

"John B. Matthews" <nospam@nospam.invalid>
Wed, 12 Aug 2009 18:38:36 -0400
In article
 bH <> wrote:

On Aug 10, 11:01??pm, "John B. Matthews" <nos...@nospam.invalid> wrote:

In article
<> wrote:


Finally, you wanted information about telnet and port in a
Windows XP. My internet wanderings suggest that it is but with
specifics to ports, security and firewalls.

In the interim, I stumbled across a machine running Vista, and I
thought I'd give it a try. Enabling telnet turned out to be an
obscure, tedious administrative task. Moreover, it proved easier to
com[m]andeer an open port that to finesse the firewall.

When I finally got the programs to run with frames, I placed them
in jars. And now each can be used as a click on it to demonstrate
EchoServer and EchoClient.

Capital idea! You probably finished before me. :-)


Hi John,
The following is my effort to revise your code to
my EchoServer. I do not understand how to write a
thread in a similar manner that you did. Yet I did
use some of lines that you have written.
It is necessary in this situation to have the
EchoServer to be running when the EchoClient
is started.
Thanks again for your efforts.

It looks like your EchoClient is blocking the EDT in actionPerformed().
As client and server are largely symmetric, here's an example that does

package net;

import java.awt.*;
import java.awt.event.*;
import java.util.Scanner;
import javax.swing.*;

 * A simple network client-server pair
 * @author John B. Matthews
public class Echo implements ActionListener, Runnable {

    private static final String HOST = "";
    private static final int PORT = 12345;
    private final JTextField tf = new JTextField(25);
    private final JTextArea ta = new JTextArea(15, 25);
    private final JButton send = new JButton("Send");
    private volatile PrintWriter out;
    private Scanner in;
    private Thread client;
    private Kind kind;

    public static enum Kind {
        Client(100, "Trying"), Server(500, "Awaiting");
        private int offset;
        private String activity;
        private Kind(int offset, String activity) {
            this.offset = offset;
            this.activity = activity;

    public Echo(Kind kind) {
        this.kind = kind;
        JFrame f = new JFrame("Echo " + kind);
        f.add(tf, BorderLayout.NORTH);
        f.add(new JScrollPane(ta), BorderLayout.CENTER);
        f.add(send, BorderLayout.SOUTH);
        f.setLocation(kind.offset, 300);
        display(kind.activity + HOST + " on port " + PORT);
        client = new Thread(this, "Client");

    public void start() {

    public void actionPerformed(ActionEvent ae) {
        String s = tf.getText();
        if (out != null) {

    public void run() {
        try {
            Socket socket;
            if (kind == Kind.Client) {
                socket = new Socket(HOST, PORT);
            } else {
                ServerSocket ss = new ServerSocket(PORT);
                socket = ss.accept();
            in = new Scanner(socket.getInputStream());
            out = new PrintWriter(socket.getOutputStream(), true);
            while (true) {
        } catch (Exception e) {

    private void display(String s) {
        ta.append(s + "\u23CE\n");

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Echo(Kind.Server).start();
                new Echo(Kind.Client).start();

John B. Matthews
trashgod at gmail dot com

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