Hamed Minaee Hamed Minaee - 2 months ago 25
Java Question

Sentiment analysis with standford nlp does not work

I am trying to use standford nlp to get the sentiment of a text:
Here is my code:

import java.util.Properties;

import edu.stanford.nlp.ling.CoreAnnotations;
import edu.stanford.nlp.pipeline.Annotation;
import edu.stanford.nlp.pipeline.StanfordCoreNLP;
import edu.stanford.nlp.rnn.RNNCoreAnnotations;
import edu.stanford.nlp.sentiment.SentimentCoreAnnotations;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.util.CoreMap;

public class SentimentAnalyzer {

public static void main(String[] args) {
findSentiment("");
}

public static void findSentiment(String line) {
line = "I started taking the little pill about 6 years ago.";
Properties props = new Properties();
props.setProperty("annotators", "tokenize, ssplit, parse, sentiment");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);
int mainSentiment = 0;
if (line != null && line.length() > 0) {
int longest = 0;
Annotation annotation = pipeline.process(line);
for (CoreMap sentence : annotation
.get(CoreAnnotations.SentencesAnnotation.class)) {
Tree tree = sentence
.get(SentimentCoreAnnotations.AnnotatedTree.class);
int sentiment = RNNCoreAnnotations.getPredictedClass(tree);
String partText = sentence.toString();
if (partText.length() > longest) {
mainSentiment = sentiment;
longest = partText.length();
}

}
}
if (mainSentiment == 2 || mainSentiment > 4 || mainSentiment < 0) {
System.out.println("Neutral " + line);
}
else{
}
/*
* TweetWithSentiment tweetWithSentiment = new TweetWithSentiment(line,
* toCss(mainSentiment)); return tweetWithSentiment;
*/

}
}


Also I use the instruction from this link:
https://blog.openshift.com/day-20-stanford-corenlp-performing-sentiment-analysis-of-twitter-using-java/

But I get the following error:

Exception in thread "main" java.lang.NullPointerException
at edu.stanford.nlp.rnn.RNNCoreAnnotations.getPredictedClass(RNNCoreAnnotations.java:58)
at SentimentAnalyzer.findSentiment(SentimentAnalyzer.java:27)
at SentimentAnalyzer.main(SentimentAnalyzer.java:14)


which point to this line:

Tree tree = sentence.get(SentimentCoreAnnotations.AnnotatedTree.class);


Does anyone have any idea?

Answer

Use this instead:

Tree tree = sentence.get(SentimentCoreAnnotations.SentimentAnnotatedTree.class);

Edit: To get positive, negative, and neutral comments, use this snippet:

switch (mainSentiment) {
        case 0:
            return "Very Negative";
        case 1:
            return "Negative";
        case 2:
            return "Neutral";
        case 3:
            return "Positive";
        case 4:
            return "Very Positive";
        default:
            return "";
        }
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