import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectOutputStream;

import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.http.AccessToken;
import twitter4j.http.RequestToken;

public class Twitter4JRegister {


  public static void main(String args[]) throws Exception {

    Twitter twitter = new TwitterFactory().getInstance();
    twitter.setOAuthConsumer("consumer key", "consumer secret");
    RequestToken requestToken = twitter.getOAuthRequestToken();
    AccessToken accessToken = null;
    BufferedReader bufferedReader = new BufferedReader(
        new InputStreamReader(System.in));
    while (null == accessToken) {
      System.out
          .println("Open the following URL and grant access to your account:");
      System.out.println(requestToken.getAuthorizationURL());
      System.out
          .print("Enter the generated PIN:");
      String pin = bufferedReader.readLine();
      try {
        if (pin.length() > 0) {
          accessToken = twitter
              .getOAuthAccessToken(requestToken, pin);
        } else {
          accessToken = twitter.getOAuthAccessToken();
        }

      } catch (TwitterException e) {
        if (401 == e.getStatusCode()) {
          System.out.println("Unable to get the access token.");
        } else {
          e.printStackTrace();
        }
      }
    }
    storeAccessToken(accessToken);
    Status status = twitter.updateStatus("Client installed");
    System.out.println("Successfully updated the status to ["
        + status.getText() + "].");
    System.exit(0);
  }

  private static void storeAccessToken(AccessToken accessToken) {

    try {
      FileOutputStream fileOutputStream = new FileOutputStream(
          "token.txt");
      ObjectOutputStream objectOutputStream = new ObjectOutputStream(
          fileOutputStream);
      objectOutputStream.writeObject(accessToken.getToken());
      objectOutputStream.flush();
      fileOutputStream = new FileOutputStream("tokenSecret.txt");
      objectOutputStream = new ObjectOutputStream(fileOutputStream);
      objectOutputStream.writeObject(accessToken.getTokenSecret());

      objectOutputStream.flush();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }

  }

}

import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;

import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterFactory;
import twitter4j.http.AccessToken;

public class Twitter4JUpdate {

  public static void main(String args[]) throws Exception {

    TwitterFactory factory = new TwitterFactory();
    AccessToken accessToken = loadAccessToken();
    Twitter twitter = factory.getOAuthAuthorizedInstance("consumer key",
        "consumer secret", accessToken);
    Status status = twitter.updateStatus("Client registered");
    System.out.println("Successfully updated the status to ["
        + status.getText() + "].");
    System.exit(0);
  }

  private static AccessToken loadAccessToken() {
    String token = null;
    String tokenSecret = null;
    try {
      FileInputStream fileInputStream = new FileInputStream("token.txt");
      ObjectInputStream objectInputStream = new ObjectInputStream(
          fileInputStream);
      token = (String) objectInputStream.readObject();
      fileInputStream = new FileInputStream("tokenSecret.txt");
      objectInputStream = new ObjectInputStream(fileInputStream);
      tokenSecret = (String) objectInputStream.readObject();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return new AccessToken(token, tokenSecret);

  }

}

java Twitter4JUpdate update

import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;

import org.apache.tools.ant.Task;

import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.http.AccessToken;

public class TweetTask extends Task {

  private String status;

  public void execute() {

try {

      TwitterFactory factory = new TwitterFactory();
      AccessToken accessToken = loadAccessToken();
      Twitter twitter = factory.getOAuthAuthorizedInstance(
          "consumer key", "consumer secret", accessToken);
      Status updatedStatus = twitter.updateStatus(status);
      System.out.println("Updated status to: "
          + updatedStatus.getText());

    } catch (TwitterException e) {

      e.printStackTrace();

    }

  }

  private AccessToken loadAccessToken() {

    String token = null;
    String tokenSecret = null;
    try {
      FileInputStream fileInputStream = new FileInputStream(
          "accessToken.txt");
      ObjectInputStream objectInputStream = new ObjectInputStream(
          fileInputStream);
      token = (String) objectInputStream.readObject();
      fileInputStream = new FileInputStream("accessTokenSecret.txt");
      objectInputStream = new ObjectInputStream(fileInputStream);
      tokenSecret = (String) objectInputStream.readObject();
    } catch (IOException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
    }
    return new AccessToken(token, tokenSecret);

  }

  public String getStatus() {
    return status;
  }

  public void setStatus(String status) {
    this.status = status;
  }

}

<?xml version="1.0" encoding="UTF-8"?>
<project default="default" basedir=".">

  <taskdef name="tweet"
     classname="TweetTask"
     classpath="Twitter4J Jar file" />

  <target name="default">
  
    <tstamp>
      <format property="build.completed" 
        pattern="HH:mm:ss z dd-MM-yyyy" />
    </tstamp>
    <tweet status="build completed at ${build.completed}" />
    
  </target>
  
</project>