Get the TCP/IP address, not localhost

Question

I found this code in the book Java 2 : Exam Guide by Barry Boone and William R Stanek. This code is giving me the internal IP 127.0.0.1 But I want something like 115.245.12.61. How could I get this. I am providing my code below

import java.io.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;

public class SingleChat extends Panel {
    Socket sock;
    TextArea ta_RecText;
    private GridBagConstraints c;
    private GridBagLayout gridBag;
    private Frame frame;
    private Label label;
    public int port = 5001;
    private TextField tf_Send;
    private DataOutputStream remoteOut;
    static String szUserName = "";

    public static void main (String [] args){
        final Frame f = new Frame("Waiting For Connection...");
        String s = null;
        Color fore , back;
        fore = new java.awt.Color(255, 255, 255);
        back = new java.awt.Color(0, 173, 232);
        if (args.length > 0)
            s = args[0];
        SingleChat chat = new SingleChat(f);
        Panel pane = new Panel(), butPane = new Panel();
        Label l_Label = new Label("//RADconnect");
        l_Label.setForeground(fore);
        l_Label.setBackground(back);
        l_Label.setFont(new java.awt.Font("Lucida Console", 0, 24));
        pane.add(l_Label);
        f.setForeground(fore);
        f.setBackground(back);
        f.add("North", pane);
        f.add("Center", chat);
        Button but = new Button("EXIT");
        but.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(ActionEvent e) {
                f.dispose();
                System.exit(0);
            }
        });
        but.setBackground(fore);
        but.setForeground(back);
        butPane.add(but);
        f.add("South", butPane);
        f.setSize(450, 350);
        f.show();
        if (s == null){
            chat.server();
        }
        else{
            chat.client(s);
        }
    }

    public SingleChat (Frame f){
        frame = f;
        frame.addWindowListener(new WindowExitHandler());
        Insets insets = new Insets (10, 20, 5, 10);
        gridBag = new GridBagLayout();
        setLayout(gridBag);
        c = new GridBagConstraints();
        c.insets = insets;
        c.gridx = 0;
        c.gridx = 0;
        label = new Label("Text To Send:");
        gridBag.setConstraints(label, c);
        add(label);
        c.gridx = 1;
        tf_Send = new TextField(40);
        tf_Send.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(ActionEvent e) {
                try{
                    //Intercept Messages And Send Them
                    String msg = tf_Send.getText();
                    remoteOut.writeUTF(szUserName+": "+msg);
                    tf_Send.setText("");
                    ta_RecText.append(szUserName+": "+msg+"\n");
                } catch (IOException x) {
                    displayMsg(x.getMessage()+": Connection to Peer Lost");
                }
            }
        });
        gridBag.setConstraints(tf_Send, c);
        add(tf_Send);
        c.gridy = 1;
        c.gridx = 0;
        label = new Label("Text Recived:");
        gridBag.setConstraints(label, c);
        add(label);
        c.gridx = 1;
        ta_RecText = new TextArea(5, 40);
        gridBag.setConstraints(ta_RecText, c);
        add(ta_RecText);
        ta_RecText.setForeground(Color.BLACK);
        tf_Send.setForeground(Color.BLACK);
    }

    private void server(){
        ServerSocket sv_Sock = null;
        try {
            InetAddress sv_Addr = InetAddress.getByName(null);
            displayMsg("Waiting For Connection on "+sv_Addr.getHostAddress()+":"+port);
            sv_Sock = new ServerSocket(port, 1);
            sock = sv_Sock.accept();
            displayMsg("Accepted Connection From "+sock.getInetAddress().getHostName());
            remoteOut = new DataOutputStream(sock.getOutputStream());
            new SingleChatRecive(this).start();
        } catch (IOException x){
            displayMsg(x.getMessage()+": Falied to connect to client");
        }
        finally {
            if (sv_Sock != null){
                try{
                    sv_Sock.close();
                } catch (IOException x){
                }
            }
        }
    }
    private void client(String sv_Name){
        try {
            if (sv_Name.equals("local")){
                sv_Name = null;
            }
            InetAddress sv_Addr = InetAddress.getByName(sv_Name);
            sock = new Socket(sv_Addr.getHostName(), port);
            remoteOut = new DataOutputStream(sock.getOutputStream());
             displayMsg("Connected to Server "+sv_Addr.getHostName()+":"+sock.getPort());
             new SingleChatRecive(this).start();
        } catch (IOException e){
            displayMsg(e.getMessage()+": Failed to connect to server");
        }
    }
    void displayMsg(String sz_Title){
        frame.setTitle(sz_Title);
    }
    protected void finalize() throws Throwable {
        try {
            if (remoteOut != null){
                remoteOut.close();
            }
            if (sock != null){
                sock.close();
            }
        } catch (IOException e){
        }
        super.finalize();
    }
    class WindowExitHandler extends WindowAdapter{
        public void windowClosing(WindowEvent e){
            Window w = e.getWindow();
            w.setVisible(false);
            w.dispose();
            System.exit(0);
        }
    }
    void saveData(){

    }
}

class SingleChatRecive extends Thread {
    private SingleChat chat;
    private DataInputStream remoteIn;
    private boolean listening = true;
    public SingleChatRecive(SingleChat chat){
        this.chat = chat;
    }
    public synchronized void run(){
        String s;
        try {
            remoteIn = new DataInputStream(chat.sock.getInputStream());
            while (listening) {
                s = remoteIn.readUTF();
                chat.ta_RecText.append(s+"\n");
            }
        } catch (IOException e){
            chat.displayMsg(e.getMessage()+": Connection to Peer Lost!");
        } finally {
            try {
                if (remoteIn != null) {
                    remoteIn.close();
                }
            } catch (IOException e){
            }
        }
    }
}

What changes could be done to avoid getting 127.0.0.1 THANKS

Answer 1

From your code:

InetAddress sv_Addr = InetAddress.getByName(null);

From the javadoc: "If the host is null then an InetAddress representing an address of the loopback interface is returned."

The IP address of the loopback interface is 127.0.0.1.

To get other IP addresses you must exchange null with a valid host name. Your local machine name could do if that is where you are running your server, but any valid host name should work.

InetAddress sv_Addr = InetAddress.getByName("myserver.mydomain.com");