Smack API

Smack is an Open Source XMPP (Jabber) Java client library.
Writing a gTalk (Jabber/XMPP) client in Java has a example code. But it has exception.

java.lang.NullPointerException
at org.jivesoftware.smack.sasl.SASLMechanism.authenticate(SASLMechanism.java:117)

Just set SASL Authentication is disable, like below.
config.setSASLAuthenticationEnabled(false);

The complete java code is:

import java.util.*;
import java.io.*;

import org.jivesoftware.smack.Chat;
import org.jivesoftware.smack.packet.Message;
import org.jivesoftware.smack.ConnectionConfiguration;
import org.jivesoftware.smack.MessageListener;
import org.jivesoftware.smack.Roster;
import org.jivesoftware.smack.RosterEntry;
import org.jivesoftware.smack.XMPPConnection;
import org.jivesoftware.smack.XMPPException;

public class ChatClient implements MessageListener {
    XMPPConnection connection;

    public void login(String userName, String password) throws XMPPException {
        ConnectionConfiguration config = new ConnectionConfiguration(
                "talk.google.com", 5222, "gmail.com");
        config.setCompressionEnabled(true);
        config.setSASLAuthenticationEnabled(false);
        connection = new XMPPConnection(config);

        connection.connect();
        connection.login(userName, password);
    }

    public void sendMessage(String message, String to) throws XMPPException {
        Chat chat = connection.getChatManager().createChat(to, this);
        chat.sendMessage(message);
    }

    public void displayBuddyList() {
        Roster roster = connection.getRoster();
        roster.setSubscriptionMode(Roster.SubscriptionMode.accept_all);
        Collection<RosterEntry> entries = roster.getEntries();

        System.out.println("\n\n" + entries.size() + " buddy(ies):");
        for (RosterEntry r : entries) {
            System.out.println(r.getUser());
        }
    }

    public void disconnect() {
        connection.disconnect();
    }

    public void processMessage(Chat chat, Message message) {
        if (message.getType() == Message.Type.chat)
            System.out.println(chat.getParticipant() + " says: "
                    + message.getBody());
    }

    public static void main(String args[]) throws XMPPException, IOException {
        // declare variables
        ChatClient c = new ChatClient();
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String msg;

        // turn on the enhanced debugger
        XMPPConnection.DEBUG_ENABLED = false;

        // provide your login information here
        c.login("SendAccount", "SendPassword");

        c.displayBuddyList();
        System.out.println("-----");
        System.out.println("Enter your message in the console.");
        System.out.println("All messages will be sent to abhijeet.maharana");
        System.out.println("-----\n");

        while (!(msg = br.readLine()).equals("bye")) {
            // your buddy's gmail address goes here
            c.sendMessage(msg, "XXXXX@gmail.com");
        }

        c.disconnect();
        System.exit(0);
    }
}