I want to use CoreNLP in my Android project. But when I create a CoreNLP instance like this:
import java.util.Properties;
import edu.stanford.nlp.ling.CoreAnnotations;
import edu.stanford.nlp.neural.rnn.RNNCoreAnnotations;
import edu.stanford.nlp.pipeline.Annotation;
import edu.stanford.nlp.pipeline.StanfordCoreNLP;
import edu.stanford.nlp.sentiment.SentimentCoreAnnotations;
import edu.stanford.nlp.trees.Tree;
import edu.stanford.nlp.util.CoreMap;
public class NLP {
private StanfordCoreNLP pipeline;
Properties props;
public NLP() {
props = new Properties();
props.setProperty("annotators", "tokenize, ssplit, pos, parse, sentiment");
pipeline = new StanfordCoreNLP(props);//-->ERROR, SEE BELOW
}
public int findSentiment(String line) {
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();
}
}
}
return mainSentiment;
}
}
The project links to the following .jar files:
On my desktop java environment with java 1.8.0_92, this code runs correctly, but when running the code on an Android (after compiling without error), I am getting the error when the NLP class is instantiated:
Caused by: java.lang.IllegalArgumentException: Can't return head of null or leaf Tree. at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:158) at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:138) at edu.stanford.nlp.pipeline.ParserAnnotator.(ParserAnnotator.java:132) at edu.stanford.nlp.pipeline.AnnotatorImplementations.parse(AnnotatorImplementations.java:132) at edu.stanford.nlp.pipeline.StanfordCoreNLP$10.create(StanfordCoreNLP.java:719) at edu.stanford.nlp.pipeline.AnnotatorPool.get(AnnotatorPool.java:85) at edu.stanford.nlp.pipeline.StanfordCoreNLP.construct(StanfordCoreNLP.java:292) at edu.stanford.nlp.pipeline.StanfordCoreNLP.(StanfordCoreNLP.java:129) at edu.stanford.nlp.pipeline.StanfordCoreNLP.(StanfordCoreNLP.java:125)
I am using CoreNLP 3.4.1. It's not the most recent version, but it works with Java 7 on Android. How can I use CoreNLP correctly on Android?
I was looking for the answer. I have checked the jar. There is a class AbstractCollinsHeadFinder.java. From this class, this error comes
edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:158) at edu.stanford.nlp.trees.AbstractCollinsHeadFinder.determineHead(AbstractCollinsHeadFinder.java:138)
There are 2 root causes for this error.
If tree is leaf, then this error occurs.
@Override
public Tree determineHead(Tree t, Tree parent) {
if (nonTerminalInfo == null) {
throw new IllegalStateException("Classes derived from AbstractCollinsHeadFinder must create and fill HashMap nonTerminalInfo.");
}
// The error mainly generate for the following condition
if (t == null || t.isLeaf()) {
throw new IllegalArgumentException("Can't return head of null or leaf Tree.");
}
if (DEBUG) {
log.info("determineHead for " + t.value());
}
Tree[] kids = t.children();
-------------
-------------
return theHead;
}
I have also checked your code. In your setProperty(...), there are some parameters. Maybe there are some parameter missing. So, you can create a object by following the code.
// creates a StanfordCoreNLP object, with POS tagging, lemmatization, NER, parsing, and coreference resolution
Properties props = new Properties();
props.setProperty("annotators", "tokenize, ssplit, pos, lemma, ner, parse, dcoref");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);
creates a StanfordCoreNLP object
import java.io.*;
import java.util.*;
import edu.stanford.nlp.io.*;
import edu.stanford.nlp.ling.*;
import edu.stanford.nlp.pipeline.*;
import edu.stanford.nlp.trees.*;
import edu.stanford.nlp.trees.TreeCoreAnnotations.*;
import edu.stanford.nlp.util.*;
public class StanfordCoreNlpExample {
public static void main(String[] args) throws IOException {
PrintWriter xmlOut = new PrintWriter("xmlOutput.xml");
Properties props = new Properties();
props.setProperty("annotators",
"tokenize, ssplit, pos, lemma, ner, parse");
StanfordCoreNLP pipeline = new StanfordCoreNLP(props);
Annotation annotation = new Annotation(
"This is a short sentence. And this is another.");
pipeline.annotate(annotation);
pipeline.xmlPrint(annotation, xmlOut);
// An Annotation is a Map and you can get and use the
// various analyses individually. For instance, this
// gets the parse tree of the 1st sentence in the text.
List<CoreMap> sentences = annotation
.get(CoreAnnotations.SentencesAnnotation.class);
if (sentences != null && sentences.size() > 0) {
CoreMap sentence = sentences.get(0);
Tree tree = sentence.get(TreeAnnotation.class);
PrintWriter out = new PrintWriter(System.out);
out.println("The first sentence parsed is:");
tree.pennPrint(out);
}
}
}