Develop Reference

How can I call a Go function from Java using the Java native interface?

It is possible to call C methods through the JNA interface in Java. How can I reach the same functionality with Go?
package main
import "fmt"
import "C"
//export Add
func Add(x, y int) int {
fmt.Printf("Go says: adding %v and %v\n", x, y)
return x + y
}

After review of the documentation about Go Shared Libraries:
It is possible to integrate the call of Go functions from Java Spring Batch. Below is a short example:
Go function:
package main
import "fmt"
import "C"
//export Add
func Add(x, y int) int {
fmt.Printf("Go says: adding %v and %v\n", x, y)
return x + y
}
After that, execute the command to generate the binary files:
go build -buildmode=c-shared -o bin/lib-cqm-transformer.so src/cqm_transformer.go
This generates the binary files:
ls -la bin/
total 2860
drwxrwxr-x 2 dmotta dmotta 4096 abr 23 01:13 .
drwxrwxr-x 5 dmotta dmotta 4096 abr 23 00:35 ..
-rw-r--r-- 1 root root 1558 abr 23 01:13 lib-cqm-transformer.h
-rw-r--r-- 1 root root 2915112 abr 23 01:13 lib-cqm-transformer.so
Finally, create the JNA class:
package com.XX.XX.batch.engine.transformer;
import com.sun.jna.Library;
import com.sun.jna.Native;
public class GoEngineTransformerTest {
static GoCqmTransformer GO_CQM_TRANSFORMER;
static {
String os = System.getProperty("os.name").toLowerCase();
String libExtension;
if (os.contains("mac os")) {
libExtension = "dylib";
} else if (os.contains("windows")) {
libExtension = "dll";
} else {
libExtension = "so";
}
String pwd = System.getProperty("user.dir");
String lib = pwd + "/golang/bin/lib-cqm-transformer." + libExtension;
GO_CQM_TRANSFORMER = (GoCqmTransformer) Native.loadLibrary(lib, GoCqmTransformer.class);
}
public interface GoCqmTransformer extends Library {
long Add(long x, long y);
}
public static void main(String[] args) {
System.out.println("Java says: about to call Go ..");
long total = GO_CQM_TRANSFORMER.Add(30, 12);
System.out.println("Java says: result is " + total);
}
}
After that, execute from the main Java class. Results:
Java HotSpot(TM) 64-Bit Server VM warning: You have loaded library /tmp/jna1412558273325390219.tmp which might have disabled stack guard. The VM will try to fix the stack guard now.
It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.
Java says: about to call Go ..
Go says: adding 30 and 12
Java says: result is 42

Unable to resolve class com.cloudbees.hudson.plugins.folder.Folder

I am trying to gather data from jenkins using groovy script and getting an error:
unable to resolve class com.cloudbees.hudson.plugins.folder.Folder
Below is the code:
import jenkins.model.*
import hudson.model.*
import groovy.time.TimeCategory
use ( TimeCategory ) {
// e.g. find jobs not run in last 1 year
sometimeago = (new Date() - 1.year)
}
jobs = Jenkins.instance.getAllItems()
lastabort = null
jobs.each { j ->
if (j instanceof com.cloudbees.hudson.plugins.folder.Folder) { return }
numbuilds = j.builds.size()
if (numbuilds == 0) {
println 'JOB: ' + j.fullName
println ' -> no build'
return
}
lastbuild = j.builds[numbuilds - 1]
if (lastbuild.timestamp.getTime() < sometimeago) {
println 'JOB: ' + j.fullName
println ' -> lastbuild: ' + lastbuild.displayName + ' = ' + lastbuild.result + ', time: ' + lastbuild.timestampString2
}
}
The error is:
rg.codehaus.groovy.control.MultipleCompilationErrorsExceptio‌​n:
startup failed: Script1.groovy: 12: unable to resolve class
com.cloudbees.hudson.plugins.folder.Folder # line 12, column 20. if (j
instanceof com.cloudbees.hudson.plugins.folder.Folder) { return } ^ 1
error at
org.codehaus.groovy.control.ErrorCollector.failIfErrors(Erro‌​rCollector.java:302)

I see Folder.java in jenkinsci/cloudbees-folder-plugin.
That means you need to:
check if you do have JENKINS/CloudBees Folders Plugin installed, or your groovy script would not be able to resolve that dependency.
Add "import com.cloudbees.hudson.plugins.folder.*" to be sure the script is able to make the instanceOf work.

When running groovy scripts that import libraries in Jenkins, check that your Jenkins build step is an "Execute system Groovy script", not a plain old "Execute Groovy script".
The 'system' scripts run on the existing JVM, as opposed to spawning a new one and therefore losing access to the shared libraries available to the original Jenkins JVM instance.
Groovy Script vs System Groovy Script - https://plugins.jenkins.io/groovy/

Issue in R arules package using java

For a university project I have to implement arules(package of R) in java. I have successfully integrated R and java using JRI. I did not understand how to get output of "inspect(Groceries[1:1])". I have tried with asString(),asString[]() but this gives me following error:
Exception in thread "main" java.lang.NullPointerException
at TestR.main(TestR.java:11)
Also, how can implement summary(Groceries) in java? How to get output of summary in String array or string?
R code:
>data(Groceries)
>inspect(Groceries[1:1])
>summary(Groceries)
Java code:
import org.rosuda.JRI.Rengine;
import org.rosuda.JRI.REXP;
public class TestR {
public static void main(String[] args){
Rengine re = new Rengine(new String[]{"--no-save"}, false, null);
re.eval("library(arules)");
re.eval("data(Groceries)");
REXP result = re.eval("inspect(Groceries[1:1])");
System.out.println(result.asString());
}
}

Appears that the inspect function in pkg:arules returns NULL. The output you see is a "side-effect". You can attempt to "capture output" but this is untested since I don't have experience with this integration across languages. Try instead.:
REXP result = re.eval("capture.output( inspect(Groceries[1:1]) )");
In an R console session you will get:
library(arules)
data("Adult")
rules <- apriori(Adult)
val <- inspect(rules[1000])
> str(val)
NULL
> val.co <- capture.output(inspect(rules[1000]))
> val.co
[1] " lhs rhs support confidence lift"
[2] "1 {education=Some-college, "
[3] " sex=Male, "
[4] " capital-loss=None} => {native-country=United-States} 0.1208181 0.9256471 1.031449"
But I haven't tested this in a non-interactive session. May need to muck with the file argument to capture.output, ... or it may not work at all.

What's the idiomatic way to do this Java function in Clojure?

I'm replicating this Java function into Clojure.
Config createConfig(Map<String, String> options) {
Config conf = new Config();
String foo = options.get("foo");
if (foo != null) { conf.setFoo(foo); }
String bar = options.get("bar");
if (bar != null) { conf.setBar(bar); }
// many other configs
return conf;
}
I came up with this,
(defn create-config [options]
(let [conf (Config.)]
(when-let [a (:foo options)] (.setFoo a))
(when-let [a (:bar options)] (.setBar a))
conf))
Is there a better way to do this?

How about this?
(defn create-config [{:keys (foo bar)}]
(let [config (Config.)]
(when foo (.setFoo config foo))
(when bar (.setBar config bar))))
Probably better would be to create a generic macro that can set any number of fields on an object based on a Clojure map. This could be prettier, but it works:
(defmacro set-fields
[options obj]
(let [o (gensym)
m (gensym)]
`(let [~m ~options
~o ~obj]
~#(map (fn [[field value]]
(let [setter (symbol (str "set" (clojure.string/capitalize (name field))))]
`(. ~o (~setter ~value))))
options)
~o)))
;; call like:
(set-fields {:daemon true :name "my-thread"} (Thread.))
;; translates to:
;; (let [G__1275 {:daemon true, :name "my-thread"}
;; G__1274 (Thread.)]
;; (. G__1274 (setDaemon true))
;; (. G__1274 (setName "my-thread"))
;; G__1274)
I'm not checking for null as this only looks at exactly what is passed in the options.

maybe checkout some->>
fillertext fillertext

java.lang.NullPointerException in OpenNLP using RJB (Ruby Java Bridge)

I am trying to use the open-nlp Ruby gem to access the Java OpenNLP processor through RJB (Ruby Java Bridge). I am not a Java programmer, so I don't know how to solve this. Any recommendations regarding resolving it, debugging it, collecting more information, etc. would be appreciated.
The environment is Windows 8, Ruby 1.9.3p448, Rails 4.0.0, JDK 1.7.0-40 x586. Gems are rjb 1.4.8 and louismullie/open-nlp 0.1.4. For the record, this file runs in JRuby but I experience other problems in that environment and would prefer to stay native Ruby for now.
In brief, the open-nlp gem is failing with java.lang.NullPointerException and Ruby error method missing. I hesitate to say why this is happening because I don't know, but it appears to me that the dynamic loading of the Jars file opennlp.tools.postag.POSTaggerME#1b5080a cannot be accessed, perhaps because OpenNLP::Bindings::Utils.tagWithArrayList isn't being set up correctly. OpenNLP::Bindings is Ruby. Utils, and its methods, are Java. And Utils is supposedly the "default" Jars and Class files, which may be important.
What am I doing wrong, here? Thanks!
The code I am running is copied straight out of github/open-nlp. My copy of the code is:
class OpennlpTryer
$DEBUG=false
# From https://github.com/louismullie/open-nlp
# Hints: Dir.pwd; File.expand_path('../../Gemfile', __FILE__);
# Load the module
require 'open-nlp'
#require 'jruby-jars'
=begin
# Alias "write" to "print" to monkeypatch the NoMethod write error
java_import java.io.PrintStream
class PrintStream
java_alias(:write, :print, [java.lang.String])
end
=end
=begin
# Display path of jruby-jars jars...
puts JRubyJars.core_jar_path # => path to jruby-core-VERSION.jar
puts JRubyJars.stdlib_jar_path # => path to jruby-stdlib-VERSION.jar
=end
puts ENV['CLASSPATH']
# Set an alternative path to look for the JAR files.
# Default is gem's bin folder.
# OpenNLP.jar_path = '/path_to_jars/'
OpenNLP.jar_path = File.join(ENV["GEM_HOME"],"gems/open-nlp-0.1.4/bin/")
puts OpenNLP.jar_path
# Set an alternative path to look for the model files.
# Default is gem's bin folder.
# OpenNLP.model_path = '/path_to_models/'
OpenNLP.model_path = File.join(ENV["GEM_HOME"],"gems/open-nlp-0.1.4/bin/")
puts OpenNLP.model_path
# Pass some alternative arguments to the Java VM.
# Default is ['-Xms512M', '-Xmx1024M'].
# OpenNLP.jvm_args = ['-option1', '-option2']
OpenNLP.jvm_args = ['-Xms512M', '-Xmx1024M']
# Redirect VM output to log.txt
OpenNLP.log_file = 'log.txt'
# Set default models for a language.
# OpenNLP.use :language
OpenNLP.use :english # Make sure this is lower case!!!!
# Simple tokenizer
OpenNLP.load
sent = "The death of the poet was kept from his poems."
tokenizer = OpenNLP::SimpleTokenizer.new
tokens = tokenizer.tokenize(sent).to_a
# => %w[The death of the poet was kept from his poems .]
puts "Tokenize #{tokens}"
# Maximum entropy tokenizer, chunker and POS tagger
OpenNLP.load
chunker = OpenNLP::ChunkerME.new
tokenizer = OpenNLP::TokenizerME.new
tagger = OpenNLP::POSTaggerME.new
sent = "The death of the poet was kept from his poems."
tokens = tokenizer.tokenize(sent).to_a
# => %w[The death of the poet was kept from his poems .]
puts "Tokenize #{tokens}"
tags = tagger.tag(tokens).to_a
# => %w[DT NN IN DT NN VBD VBN IN PRP$ NNS .]
puts "Tags #{tags}"
chunks = chunker.chunk(tokens, tags).to_a
# => %w[B-NP I-NP B-PP B-NP I-NP B-VP I-VP B-PP B-NP I-NP O]
puts "Chunks #{chunks}"
# Abstract Bottom-Up Parser
OpenNLP.load
sent = "The death of the poet was kept from his poems."
parser = OpenNLP::Parser.new
parse = parser.parse(sent)
=begin
parse.get_text.should eql sent
parse.get_span.get_start.should eql 0
parse.get_span.get_end.should eql 46
parse.get_child_count.should eql 1
=end
child = parse.get_children[0]
child.text # => "The death of the poet was kept from his poems."
child.get_child_count # => 3
child.get_head_index #=> 5
child.get_type # => "S"
puts "Child: #{child}"
# Maximum Entropy Name Finder*
OpenNLP.load
# puts File.expand_path('.', __FILE__)
text = File.read('./spec/sample.txt').gsub!("\n", "")
tokenizer = OpenNLP::TokenizerME.new
segmenter = OpenNLP::SentenceDetectorME.new
puts "Tokenizer: #{tokenizer}"
puts "Segmenter: #{segmenter}"
ner_models = ['person', 'time', 'money']
ner_finders = ner_models.map do |model|
OpenNLP::NameFinderME.new("en-ner-#{model}.bin")
end
puts "NER Finders: #{ner_finders}"
sentences = segmenter.sent_detect(text)
puts "Sentences: #{sentences}"
named_entities = []
sentences.each do |sentence|
tokens = tokenizer.tokenize(sentence)
ner_models.each_with_index do |model, i|
finder = ner_finders[i]
name_spans = finder.find(tokens)
name_spans.each do |name_span|
start = name_span.get_start
stop = name_span.get_end-1
slice = tokens[start..stop].to_a
named_entities << [slice, model]
end
end
end
puts "Named Entities: #{named_entities}"
# Loading specific models
# Just pass the name of the model file to the constructor. The gem will search for the file in the OpenNLP.model_path folder.
OpenNLP.load
tokenizer = OpenNLP::TokenizerME.new('en-token.bin')
tagger = OpenNLP::POSTaggerME.new('en-pos-perceptron.bin')
name_finder = OpenNLP::NameFinderME.new('en-ner-person.bin')
# etc.
puts "Tokenizer: #{tokenizer}"
puts "Tagger: #{tagger}"
puts "Name Finder: #{name_finder}"
# Loading specific classes
# You may want to load specific classes from the OpenNLP library that are not loaded by default. The gem provides an API to do this:
# Default base class is opennlp.tools.
OpenNLP.load_class('SomeClassName')
# => OpenNLP::SomeClassName
# Here, we specify another base class.
OpenNLP.load_class('SomeOtherClass', 'opennlp.tools.namefind')
# => OpenNLP::SomeOtherClass
end
The line which is failing is line 73: (tokens == the sentence being processed.)
tags = tagger.tag(tokens).to_a #
# => %w[DT NN IN DT NN VBD VBN IN PRP$ NNS .]
tagger.tag calls open-nlp/classes.rb line 13, which is where the error is thrown. The code there is:
class OpenNLP::POSTaggerME < OpenNLP::Base
unless RUBY_PLATFORM =~ /java/
def tag(*args)
OpenNLP::Bindings::Utils.tagWithArrayList(#proxy_inst, args[0]) # <== Line 13
end
end
end
The Ruby error thrown at this point is: `method_missing': unknown exception (NullPointerException). Debugging this, I found the error java.lang.NullPointerException. args[0] is the sentence being processed. #proxy_inst is opennlp.tools.postag.POSTaggerME#1b5080a.
OpenNLP::Bindings sets up the Java environment. For example, it sets up the Jars to be loaded and the classes within those Jars. In line 54, it sets up defaults for RJB, which should set up OpenNLP::Bindings::Utils and its methods as follows:
# Add in Rjb workarounds.
unless RUBY_PLATFORM =~ /java/
self.default_jars << 'utils.jar'
self.default_classes << ['Utils', '']
end
utils.jar and Utils.java are in the CLASSPATH with the other Jars being loaded. They are being accessed, which is verified because the other Jars throw error messages if they are not present. The CLASSPATH is:
.;C:\Program Files (x86)Java\jdk1.7.0_40\lib;C:\Program Files (x86)Java\jre7\lib;D:\BitNami\rubystack-1.9.3-12\ruby\lib\ruby\gems\1.9.1\gems\open-nlp-0.1.4\bin
The applications Jars are in D:\BitNami\rubystack-1.9.3-12\ruby\lib\ruby\gems\1.9.1\gems\open-nlp-0.1.4\bin and, again, if they are not there I get error messages on other Jars. The Jars and Java files in ...\bin include:
jwnl-1.3.3.jar
opennlp-maxent-3.0.2-incubating.jar
opennlp-tools-1.5.2-incubating.jar
opennlp-uima-1.5.2-incubating.jar
utils.jar
Utils.java
Utils.java is as follows:
import java.util.Arrays;
import java.util.ArrayList;
import java.lang.String;
import opennlp.tools.postag.POSTagger;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.namefind.NameFinderME; // interface instead?
import opennlp.tools.util.Span;
// javac -cp '.:opennlp.tools.jar' Utils.java
// jar cf utils.jar Utils.class
public class Utils {
public static String[] tagWithArrayList(POSTagger posTagger, ArrayList[] objectArray) {
return posTagger.tag(getStringArray(objectArray));
}
public static Object[] findWithArrayList(NameFinderME nameFinder, ArrayList[] tokens) {
return nameFinder.find(getStringArray(tokens));
}
public static Object[] chunkWithArrays(ChunkerME chunker, ArrayList[] tokens, ArrayList[] tags) {
return chunker.chunk(getStringArray(tokens), getStringArray(tags));
}
public static String[] getStringArray(ArrayList[] objectArray) {
String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);
return stringArray;
}
}
So, it should define tagWithArrayList and import opennlp.tools.postag.POSTagger. (OBTW, just to try, I changed the incidences of POSTagger to POSTaggerME in this file. It changed nothing...)
The tools Jar file, opennlp-tools-1.5.2-incubating.jar, includes postag/POSTagger and POSTaggerME class files, as expected.
Error messages are:
D:\BitNami\rubystack-1.9.3-12\ruby\bin\ruby.exe -e $stdout.sync=true;$stderr.sync=true;load($0=ARGV.shift) D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb
.;C:\Program Files (x86)\Java\jdk1.7.0_40\lib;C:\Program Files (x86)\Java\jre7\lib;D:\BitNami\rubystack-1.9.3-12\ruby\lib\ruby\gems\1.9.1\gems\open-nlp-0.1.4\bin
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/bin/
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/bin/
Tokenize ["The", "death", "of", "the", "poet", "was", "kept", "from", "his", "poems", "."]
Tokenize ["The", "death", "of", "the", "poet", "was", "kept", "from", "his", "poems", "."]
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:13:in `method_missing': unknown exception (NullPointerException)
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:13:in `tag'
from D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:73:in `<class:OpennlpTryer>'
from D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
Modified Utils.java:
import java.util.Arrays;
import java.util.Object;
import java.lang.String;
import opennlp.tools.postag.POSTagger;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.namefind.NameFinderME; // interface instead?
import opennlp.tools.util.Span;
// javac -cp '.:opennlp.tools.jar' Utils.java
// jar cf utils.jar Utils.class
public class Utils {
public static String[] tagWithArrayList(POSTagger posTagger, Object[] objectArray) {
return posTagger.tag(getStringArray(objectArray));
}f
public static Object[] findWithArrayList(NameFinderME nameFinder, Object[] tokens) {
return nameFinder.find(getStringArray(tokens));
}
public static Object[] chunkWithArrays(ChunkerME chunker, Object[] tokens, Object[] tags) {
return chunker.chunk(getStringArray(tokens), getStringArray(tags));
}
public static String[] getStringArray(Object[] objectArray) {
String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);
return stringArray;
}
}
Modified error messages:
Uncaught exception: uninitialized constant OpennlpTryer::ArrayStoreException
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:81:in `rescue in <class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:77:in `<class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
Revised error with Utils.java revised to "import java.lang.Object;":
Uncaught exception: uninitialized constant OpennlpTryer::ArrayStoreException
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:81:in `rescue in <class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:77:in `<class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
Rescue removed from OpennlpTryer shows error trapped in classes.rb:
Uncaught exception: uninitialized constant OpenNLP::POSTaggerME::ArrayStoreException
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:16:in `rescue in tag'
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:13:in `tag'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:78:in `<class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
Same error but with all rescues removed so it's "native Ruby"
Uncaught exception: unknown exception
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:15:in `method_missing'
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp/classes.rb:15:in `tag'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:78:in `<class:OpennlpTryer>'
D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
Revised Utils.java:
import java.util.Arrays;
import java.util.ArrayList;
import java.lang.String;
import opennlp.tools.postag.POSTagger;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.namefind.NameFinderME; // interface instead?
import opennlp.tools.util.Span;
// javac -cp '.:opennlp.tools.jar' Utils.java
// jar cf utils.jar Utils.class
public class Utils {
public static String[] tagWithArrayList(
System.out.println("Tokens: ("+objectArray.getClass().getSimpleName()+"): \n"+objectArray);
POSTagger posTagger, ArrayList[] objectArray) {
return posTagger.tag(getStringArray(objectArray));
}
public static Object[] findWithArrayList(NameFinderME nameFinder, ArrayList[] tokens) {
return nameFinder.find(getStringArray(tokens));
}
public static Object[] chunkWithArrays(ChunkerME chunker, ArrayList[] tokens, ArrayList[] tags) {
return chunker.chunk(getStringArray(tokens), getStringArray(tags));
}
public static String[] getStringArray(ArrayList[] objectArray) {
String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);
return stringArray;
}
}
I ran cavaj on Utils.class that I unzipped from util.jar and this is what I found. It differs from Utils.java by quite a bit. Both come installed with the open-nlp 1.4.8 gem. I don't know if this is the root cause of the problem, but this file is the core of where it breaks and we have a major discrepancy. Which should we use?
import java.util.ArrayList;
import java.util.Arrays;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.namefind.NameFinderME;
import opennlp.tools.postag.POSTagger;
public class Utils
{
public Utils()
{
}
public static String[] tagWithArrayList(POSTagger postagger, ArrayList aarraylist[])
{
return postagger.tag(getStringArray(aarraylist));
}
public static Object[] findWithArrayList(NameFinderME namefinderme, ArrayList aarraylist[])
{
return namefinderme.find(getStringArray(aarraylist));
}
public static Object[] chunkWithArrays(ChunkerME chunkerme, ArrayList aarraylist[], ArrayList aarraylist1[])
{
return chunkerme.chunk(getStringArray(aarraylist), getStringArray(aarraylist1));
}
public static String[] getStringArray(ArrayList aarraylist[])
{
String as[] = (String[])Arrays.copyOf(aarraylist, aarraylist.length, [Ljava/lang/String;);
return as;
}
}
Utils.java in use as of 10/07, compiled and compressed into utils.jar:
import java.util.Arrays;
import java.util.ArrayList;
import java.lang.String;
import opennlp.tools.postag.POSTagger;
import opennlp.tools.chunker.ChunkerME;
import opennlp.tools.namefind.NameFinderME; // interface instead?
import opennlp.tools.util.Span;
// javac -cp '.:opennlp.tools.jar' Utils.java
// jar cf utils.jar Utils.class
public class Utils {
public static String[] tagWithArrayList(POSTagger posTagger, ArrayList[] objectArray) {
return posTagger.tag(getStringArray(objectArray));
}
public static Object[] findWithArrayList(NameFinderME nameFinder, ArrayList[] tokens) {
return nameFinder.find(getStringArray(tokens));
}
public static Object[] chunkWithArrays(ChunkerME chunker, ArrayList[] tokens, ArrayList[] tags) {
return chunker.chunk(getStringArray(tokens), getStringArray(tags));
}
public static String[] getStringArray(ArrayList[] objectArray) {
String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);
return stringArray;
}
}
Failures are occurring in BindIt::Binding::load_klass in line 110 here:
# Private function to load classes.
# Doesn't check if initialized.
def load_klass(klass, base, name=nil)
base += '.' unless base == ''
fqcn = "#{base}#{klass}"
name ||= klass
if RUBY_PLATFORM =~ /java/
rb_class = java_import(fqcn)
if name != klass
if rb_class.is_a?(Array)
rb_class = rb_class.first
end
const_set(name.intern, rb_class)
end
else
rb_class = Rjb::import(fqcn) # <== This is line 110
const_set(name.intern, rb_class)
end
end
The messages are as follows, however they are inconsistent in terms of the particular method that is identified. Each run may display a different method, any of POSTagger, ChunkerME, or NameFinderME.
D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:110:in `import': opennlp/tools/namefind/NameFinderME (NoClassDefFoundError)
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:110:in `load_klass'
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:89:in `block in load_default_classes'
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:87:in `each'
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:87:in `load_default_classes'
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/bind-it-0.2.7/lib/bind-it/binding.rb:56:in `bind'
from D:/BitNami/rubystack-1.9.3-12/ruby/lib/ruby/gems/1.9.1/gems/open-nlp-0.1.4/lib/open-nlp.rb:14:in `load'
from D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:54:in `<class:OpennlpTryer>'
from D:/BitNami/rubystack-1.9.3-12/projects/RjbTest/app/helpers/opennlp_tryer.rb:1:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
The interesting point about these errors are that they are originating in OpennlpTryer line 54 which is:
OpenNLP.load
At this point, OpenNLP fires up RJB which uses BindIt to load the jars and classes. This is well before the errors that I was seeing at the beginning of this question. However, I can't help but think it is all related. I really don't understand the inconsistency of these errors at all.
I was able to add the logging function in to Utils.java, compile it after adding in an "import java.io.*" and compress it. However, I pulled it out because of these errors as I didn't know if or not it was involved. I don't think it was. However, because these errors are occurring during load, the method is never called anyway so logging there won't help...
For each of the other jars, the jar is loaded then each class is imported using RJB. Utils is handled differently and is specified as the "default". From what I can tell, Utils.class is executed to load its own classes?
Later update on 10/07:
Here is where I am, I think. First, I have some problem replacing Utils.java, as I described earlier today. That problem probably needs solved before I can install a fix.
Second, I now understand the difference between POSTagger and POSTaggerME because the ME means Maximum Entropy. The test code is trying to call POSTaggerME but it looks to me like Utils.java, as implemented, supports POSTagger. I tried changing the test code to call POSTagger, but it said it couldn't find an initializer. Looking at the source for each of these, and I am guessing here, I think that POSTagger exists for the sole purpose to support POSTaggerME which implements it.
The source is opennlp-tools file opennlp-tools-1.5.2-incubating-sources.jar.
What I don't get is the whole reason for Utils in the first place? Why aren't the jars/classes provided in bindings.rb enough? This feels like a bad monkeypatch. I mean, look what bindings.rb does in the first place:
# Default JARs to load.
self.default_jars = [
'jwnl-1.3.3.jar',
'opennlp-tools-1.5.2-incubating.jar',
'opennlp-maxent-3.0.2-incubating.jar',
'opennlp-uima-1.5.2-incubating.jar'
]
# Default namespace.
self.default_namespace = 'opennlp.tools'
# Default classes.
self.default_classes = [
# OpenNLP classes.
['AbstractBottomUpParser', 'opennlp.tools.parser'],
['DocumentCategorizerME', 'opennlp.tools.doccat'],
['ChunkerME', 'opennlp.tools.chunker'],
['DictionaryDetokenizer', 'opennlp.tools.tokenize'],
['NameFinderME', 'opennlp.tools.namefind'],
['Parser', 'opennlp.tools.parser.chunking'],
['Parse', 'opennlp.tools.parser'],
['ParserFactory', 'opennlp.tools.parser'],
['POSTaggerME', 'opennlp.tools.postag'],
['SentenceDetectorME', 'opennlp.tools.sentdetect'],
['SimpleTokenizer', 'opennlp.tools.tokenize'],
['Span', 'opennlp.tools.util'],
['TokenizerME', 'opennlp.tools.tokenize'],
# Generic Java classes.
['FileInputStream', 'java.io'],
['String', 'java.lang'],
['ArrayList', 'java.util']
]
# Add in Rjb workarounds.
unless RUBY_PLATFORM =~ /java/
self.default_jars << 'utils.jar'
self.default_classes << ['Utils', '']
end

SEE FULL CODE AT END FOR THE COMPLETE CORRECTED CLASSES.RB MODULE
I ran into the same problem today. I didn't quite understand why the Utils class were being used, so I modified the classes.rb file in the following way:
unless RUBY_PLATFORM =~ /java/
def tag(*args)
#proxy_inst.tag(args[0])
#OpenNLP::Bindings::Utils.tagWithArrayList(#proxy_inst, args[0])
end
end
In that way I can make the following test to pass:
sent = "The death of the poet was kept from his poems."
tokens = tokenizer.tokenize(sent).to_a
# => %w[The death of the poet was kept from his poems .]
tags = tagger.tag(tokens).to_a
# => ["prop", "prp", "n", "v-fin", "n", "adj", "prop", "v-fin", "n", "adj", "punc"]
R_G Edit:
I tested that change and it eliminated the error. I am going to have to do more testing to ensure the outcome is what should be expected. However, following that same pattern, I made the following changes in classes.rb as well:
def chunk(tokens, tags)
chunks = #proxy_inst.chunk(tokens, tags)
# chunks = OpenNLP::Bindings::Utils.chunkWithArrays(#proxy_inst, tokens,tags)
chunks.map { |c| c.to_s }
end
...
class OpenNLP::NameFinderME < OpenNLP::Base
unless RUBY_PLATFORM =~ /java/
def find(*args)
#proxy_inst.find(args[0])
# OpenNLP::Bindings::Utils.findWithArrayList(#proxy_inst, args[0])
end
end
end
This allowed the entire sample test to execute without failure. I will provide a later update regarding verification of the results.
FINAL EDIT AND UPDATED CLASSES.RB per Space Pope and R_G:
As it turns out, this answer was key to the desired solution. However, the results were inconsistent as it was corrected. We continued to drill down into it and implemented strong typing during the calls, as specified by RJB. This converts the call to use of the _invoke method where the parameters include the desired method, the strong type, and the additional parameters. Andre's recommendation was key to the solution, so kudos to him. Here is the complete module. It eliminates the need for the Utils.class that was attempting to make these calls but failing. We plan to issue a github pull request for the open-nlp gem to update this module:
require 'open-nlp/base'
class OpenNLP::SentenceDetectorME < OpenNLP::Base; end
class OpenNLP::SimpleTokenizer < OpenNLP::Base; end
class OpenNLP::TokenizerME < OpenNLP::Base; end
class OpenNLP::POSTaggerME < OpenNLP::Base
unless RUBY_PLATFORM =~ /java/
def tag(*args)
#proxy_inst._invoke("tag", "[Ljava.lang.String;", args[0])
end
end
end
class OpenNLP::ChunkerME < OpenNLP::Base
if RUBY_PLATFORM =~ /java/
def chunk(tokens, tags)
if !tokens.is_a?(Array)
tokens = tokens.to_a
tags = tags.to_a
end
tokens = tokens.to_java(:String)
tags = tags.to_java(:String)
#proxy_inst.chunk(tokens,tags).to_a
end
else
def chunk(tokens, tags)
chunks = #proxy_inst._invoke("chunk", "[Ljava.lang.String;[Ljava.lang.String;", tokens, tags)
chunks.map { |c| c.to_s }
end
end
end
class OpenNLP::Parser < OpenNLP::Base
def parse(text)
tokenizer = OpenNLP::TokenizerME.new
full_span = OpenNLP::Bindings::Span.new(0, text.size)
parse_obj = OpenNLP::Bindings::Parse.new(
text, full_span, "INC", 1, 0)
tokens = tokenizer.tokenize_pos(text)
tokens.each_with_index do |tok,i|
start, stop = tok.get_start, tok.get_end
token = text[start..stop-1]
span = OpenNLP::Bindings::Span.new(start, stop)
parse = OpenNLP::Bindings::Parse.new(text, span, "TK", 0, i)
parse_obj.insert(parse)
end
#proxy_inst.parse(parse_obj)
end
end
class OpenNLP::NameFinderME < OpenNLP::Base
unless RUBY_PLATFORM =~ /java/
def find(*args)
#proxy_inst._invoke("find", "[Ljava.lang.String;", args[0])
end
end
end

I don't think you're doing anything wrong at all. You're also not the only one with this problem. It looks like a bug in Utils. Creating an ArrayList[] in Java doesn't make much sense - it's technically legal, but it would be an array of ArrayLists, which a) is just plain odd and b) terrible practice with regard to Java generics, and c) won't cast properly to String[] like the author intends in getStringArray().
Given the way the utility's written and the fact that OpenNLP does, in fact, expect to receive a String[] as input for its tag() method, my best guess is that the original author meant to have Object[] where they have ArrayList[] in the Utils class.
Update
To output to a file in the root of your project directory, try adjusting the logging like this (I added another line for printing the contents of the input array):
try {
File log = new File("log.txt");
FileWriter fileWriter = new FileWriter(log);
BufferedWriter bufferedWriter = new BufferedWriter(fileWriter);
bufferedWriter.write("Tokens ("+objectArray.getClass().getSimpleName()+"): \r\n"+objectArray.toString()+"\r\n");
bufferedWriter.write(Arrays.toString(objectArray));
bufferedWriter.close();
}
catch (Exception e) {
e.printStackTrace();
}