Online chat program

Question

hey guys, im new to the whole networking thing, and this is my first attempt at using the internet. i am making a chat program, and having some troubles.
import java.net.*;
import javax.swing.*;
import java.io.*;
import java.awt.event.*;
import java.awt.*;
import java.util.*;
public class CHAT2 extends JFrame implements Runnable, ActionListener
    Thread Client = new Thread(this, "Client");
    DatagramSocket ds;
    public int buffer_size = 1024;
    public byte buffer[] = new byte[buffer_size];
    public final int PORT = 3677;
    JTextField jt;
    JTextArea jto;
    public CHAT2() {
    Thread.currentThread().setName("Server");
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    try {
        ds = new DatagramSocket(PORT);
        }catch(SocketException ec) {
    JPanel jp = new JPanel();
    jp.setLayout(new GridLayout(2,2));
    setTitle("MChat");
    setSize(400,400);
    setResizable(false);
    jt = new JTextField();
    jto = new JTextArea();
    jto.setFont(new Font("Arial", Font.BOLD, 12));
    jto.setForeground(Color.BLUE);
    jto.setEditable(false);
    //jt.setSize(100,20);
    //jt.setLocation(10,50);
    JButton b = new JButton("Send Message");
    //b.setSize(100,40);
    //b.setLocation(10,100);
    getContentPane().setLayout(new BorderLayout());
    //getContentPane().add(b);
    jp.add(jt);
    jp.add(b);
    getContentPane().add(jto, BorderLayout.CENTER);
    getContentPane().add(jp, BorderLayout.SOUTH);
    b.addActionListener(this);
    Client.start();
public void run() {
    try {
        for(;;) {
            buffer = new byte[buffer_size];
            DatagramPacket p = new DatagramPacket(buffer, buffer.length);
        try {
            ds.receive(p);
    }catch(IOException ec) {
    String temp = new String(p.getData(), 0, p.getLength());
    System.out.println(temp);
    if(jto.getText().length() > 1) jto.setText(jto.getText() + "\n" + temp);
    else jto.setText(temp);
    Thread.sleep(1);
    }catch(InterruptedException ec) {
public void actionPerformed(ActionEvent ae)
    send(jt.getText());
public void send(String e)
    int c = 0;
    while(c < e.length()) {
    buffer[c] = (byte) (e.charAt(c) );
    c++;
    try {
    ds.send(new DatagramPacket(buffer,c, InetAddress.getLocalHost(), PORT));
    }catch(IOException ec) {
public static void main(String args[])
    System.out.println(new Date().getDay());
    CHAT2 ch = new CHAT2();
    ch.setVisible(true);
}it works when i use it on my computer, but when trying to go across my network it does not. i have a feeling it traces back to this line
ds.send(new DatagramPacket(buffer,c, InetAddress.getLocalHost(), PORT));
any ideas on how to fix it?
(remember i am very new to networking, so dont expect me to know much....)

Answer 1

InetAddress.getLocalHost() gets your localhost ip. i.e. the ip of the computer you are running the program on which means you will send the package to the same computer. to send it to another computer enter the ip-address of it.