java.lang.NullPointerException while doing sentimental analysis with stanford-nlp API

I am new to stanford-nlp API. I am trying to just sentimental analysis with stanford API but it's throwing exception. please see the below logs.

Adding annotator tokenize
Adding annotator ssplit
Adding annotator pos
Reading POS tagger model from edu/stanford/nlp/models/pos-tagger/english-left3words/english-left3words-distsim.tagger ... done [1.4 sec].
Adding annotator lemma
Adding annotator ner
Loading classifier from edu/stanford/nlp/models/ner/english.all.3class.distsim.crf.ser.gz ... done [5.3 sec].
Loading classifier from edu/stanford/nlp/models/ner/english.muc.7class.distsim.crf.ser.gz ... done [2.3 sec].
Loading classifier from edu/stanford/nlp/models/ner/english.conll.4class.distsim.crf.ser.gz ... done [4.7 sec].
Adding annotator parse
Loading parser from serialized file edu/stanford/nlp/models/lexparser/englishPCFG.ser.gz ... done [1.1 sec].
Adding annotator dcoref
Adding annotator sentiment
Exception in thread "main" java.lang.NoClassDefFoundError: org/ejml/simple/SimpleBase
    at edu.stanford.nlp.pipeline.SentimentAnnotator.<init>    (SentimentAnnotator.java:48)
    at  edu.stanford.nlp.pipeline.StanfordCoreNLP$14.create(StanfordCoreNLP.java:850)
    at edu.stanford.nlp.pipeline.AnnotatorPool.get(AnnotatorPool.java:81)
    at edu.stanford.nlp.pipeline.StanfordCoreNLP.construct(StanfordCoreNLP.java:262)
    at edu.stanford.nlp.pipeline.StanfordCoreNLP.<init>(StanfordCoreNLP.java:129)
    at edu.stanford.nlp.pipeline.StanfordCoreNLP.<init>(StanfordCoreNLP.java:125)
    at io.stanford.NLP.findSentiment(NLP.java:30)
    at io.stanford.TestStanford.main(TestStanford.java:8)
Caused by: java.lang.ClassNotFoundException: org.ejml.simple.SimpleBase
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    ... 8 more

Solution

What is the code that produces this output? My strong suspicion is that you have not included the "sentiment" annotator in your annotators list, either in the properties file you are using to run the code, or the properties object you have passed into the annotation pipeline. Without running the sentiment annotator, the document will not have the sentiment annotations attached, and will therefore null pointer when trying to retrieve them.