Null pointer exception in Twitter twitter4j 2.2.5

Question

I have to get tweets related to search query. So I m using the twitter4j 2.2.5. When I enter a word to search It gives the error.

I have to access the tweets in the twitter and I will store it in the database and I will get the sentimental analysis in java.

public class TweetOperator {


    private static final String consumerKey = "XXXXXXXXXXXXXXXXxxxxxxxxxxx";
    private static final String consumerSecret = "XXXXXXXXXXXXXXXXxxxxxxxxxxx";;
    private static final String tokenKey = "XXXXXXXXXXXXXXXXxxxxxxxxxxx";;
    private static final String tokenSecret = "XXXXXXXXXXXXXXXXxxxxxxxxxxx";;



    Twitter twitter;


    public TweetOperator(int mode) {
        try {
            db = Operator.getInstance();
        } catch(Exception ex) {
            ex.printStackTrace();
        }
        this.mode = mode;

        AccessToken token = new AccessToken(tokenKey, tokenSecret);
        twitter.setOAuthAccessToken(token);// Exception occurs here 
          twitter =  new TwitterFactory().getInstance();
        twitter.setOAuthConsumer(consumerKey, consumerSecret);

    }

    @Override
    protected void finalize() throws Throwable{
        super.finalize();
    }





}

stack trace :

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at sentimentanalysis.twitterapi.TweetOperator.<init>(TweetOperator.java:57)
        at sentimentanalysis.search.Search.<init>(Search.java:34)
        at sentimentanalysis.view.SentimentAnalysisView.searchSubmitActionPerformed(SentimentAnalysisView.java:249)
        at sentimentanalysis.view.SentimentAnalysisView.access$200(SentimentAnalysisView.java:22)
        at sentimentanalysis.view.SentimentAnalysisView$3.actionPerformed(SentimentAnalysisView.java:135)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
        at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
        at java.awt.Component.processMouseEvent(Component.java:6505)
        at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
        at java.awt.Component.processEvent(Component.java:6270)
        at java.awt.Container.processEvent(Container.java:2229)
        at java.awt.Component.dispatchEventImpl(Component.java:4861)
        at java.awt.Container.dispatchEventImpl(Container.java:2287)
        at java.awt.Component.dispatchEvent(Component.java:4687)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
        at java.awt.Container.dispatchEventImpl(Container.java:2273)
        at java.awt.Window.dispatchEventImpl(Window.java:2719)
        at java.awt.Component.dispatchEvent(Component.java:4687)
        at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
        at java.awt.EventQueue.access$200(EventQueue.java:103)
        at java.awt.EventQueue$3.run(EventQueue.java:694)
        at java.awt.EventQueue$3.run(EventQueue.java:692)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
        at java.awt.EventQueue$4.run(EventQueue.java:708)
        at java.awt.EventQueue$4.run(EventQueue.java:706)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

Answer 1

Write your code inside

new Thread(new Runnable() {
    @Override
    public void run() {



    }
}).start();

Answer 2

Recently Twitter has upgraded its API to accept only SSL requests. But TwitterFactory by default disable SSL.

Adding to the Nigel Tufnel code, update the code as below

    ConfigurationBuilder builder = new ConfigurationBuilder();
    builder.setUseSSL(true);

    TwitterFactory factory = new TwitterFactory(builder.build());
    Twitter twitter = factory.getInstance();

Tweet was an depricated. Status was the new interface we need to use. Please check the sample program below.

package twitter;
import java.util.List;
import twitter4j.Query;
import twitter4j.QueryResult;
import twitter4j.Status;
import twitter4j.Twitter;
import twitter4j.TwitterException;
import twitter4j.TwitterFactory;
import twitter4j.auth.AccessToken;
import twitter4j.conf.ConfigurationBuilder;
public class XYZ {
public static void main(String[] args) {
    String oauth_consumer_key="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    String oauth_token="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    String oauth_consumer_secret="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    String oauth_token_secret ="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
    ConfigurationBuilder builder = new ConfigurationBuilder();
    builder.setUseSSL(true);
    TwitterFactory factory = new TwitterFactory(builder.build());
    Twitter twitter = factory.getInstance();

    twitter.setOAuthConsumer(oauth_consumer_key, oauth_consumer_secret);
    AccessToken accessToken = new AccessToken(oauth_token, oauth_token_secret);         
    twitter.setOAuthAccessToken(accessToken);  

    Query arg0 = new Query("query");
    try {
        QueryResult queryResult = twitter.search(arg0 );
        System.out.println(queryResult.getCount());
        List<Status> statuses = queryResult.getTweets();
        for(Status status:statuses){
            System.out.println(status.getText());
        }

    } catch (TwitterException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

}

Answer 3

You're assigning twitter to new TwitterFactory().getInstance() after you're calling twitter.setOAuthAccessToken. twitter instance variable is initialized to null and you're getting Null pointer exception.

Changing the line order should work:

twitter =  new TwitterFactory().getInstance();
twitter.setOAuthAccessToken(token);