opennlp.groovy has NullPointerException - groovy

Question

I am trying to get the following code snippet from GitHub to work so that I can use OpenNLP tools in Groovy scripts.
(OpenNLP class from https://gist.github.com/nagaimasato/1178725)
#!/usr/bin/env groovy
#Grapes(
#Grab(
group='org.apache.opennlp',
module='opennlp-tools',
version='1.5.3'
)
)
import opennlp.tools.tokenize.*
import opennlp.tools.postag.*
OpenNLP nlp = new OpenNLP()
def tokens = nlp.workTokenize("Hello world")
println tokens
class OpenNLP {
static TokenizerModel tokenizerModel
static POSModel posModel
static {
def classLoader = OpenNLP.class.classLoader
classLoader.getResource('opennlp/en-token.bin').withInputStream {
tokenizerModel = new TokenizerModel(it)
}
classLoader.getResource('opennlp/en-pos-maxent.bin').withInputStream {
posModel = new POSModel(it)
}
}
Tokenizer tokenizer
POSTagger tagger
OpenNLP() {
tokenizer = new TokenizerME(tokenizerModel)
tagger = new POSTaggerME(posModel)
}
List workTokenize(String text) {
return tokenizer.tokenize(text)
}
List posTag(List tokens) {
return [tokens, tagger.tag(tokens)].transpose()
}
}
I get the following error when I try to run the script:
Caught: java.lang.ExceptionInInitializerError
java.lang.ExceptionInInitializerError
at Greetings.class$(Greetings.groovy)
at Greetings.$get$$class$OpenNLP(Greetings.groovy)
at Greetings.run(Greetings.groovy:13)
Caused by: java.lang.NullPointerException: Cannot invoke method withInputStream() on null object
at OpenNLP.<clinit>(Greetings.groovy:25)
... 3 more
I have en-token.bin and en-pos-maxent.bin in the right place for the script to find, but classLoader.getResource("opennlp/en-token.bin") is indeed null when I print it. Any ideas?

Answer 1

Make sure the en-token.bin and en-pos-maxent.bin files are in a directory named opennlp and that the classpath includes the parent directory of opennlp.
Note that ./ is included in the classpath when you execute your Groovy script, so if you have your opennlp directory in the same directory as your Groovy script and you also invoke the Groovy script while you are in that directory, it should work (at least it worked for me). But if you execute the script while you are not currently in that directory (e.g. by using a path like path/to/script.groovy) it won't work. In that case, you can just invoke it using groovy -cp path/to path/to/script.groovy, thus putting the parent directory of your opennlp directory into the classpath manually.