CODEWITHSUNDEEP
javamahoutrecommendation-enginemahout-recommender
orezvani
orezvani

Reputation: 3775

NoClassDefFoundError using mahout

I am starting to learn mahout, but in the first step I got a strange error in my program. I'm trying to build a simple recommender in a few lines:

import java.util.List;
import java.io.File;
import org.apache.mahout.cf.taste.model.DataModel;
import org.apache.mahout.cf.taste.impl.model.file.FileDataModel;
import org.apache.mahout.cf.taste.similarity.UserSimilarity;
import org.apache.mahout.cf.taste.impl.similarity.PearsonCorrelationSimilarity;
import org.apache.mahout.cf.taste.neighborhood.UserNeighborhood;
import org.apache.mahout.cf.taste.impl.neighborhood.NearestNUserNeighborhood;
import org.apache.mahout.cf.taste.recommender.Recommender;
import org.apache.mahout.cf.taste.recommender.RecommendedItem;
import org.apache.mahout.cf.taste.impl.recommender.GenericUserBasedRecommender;
/**
 */
public class RecommenderIntro {
    public static void main(String[] args) throws Exception {
        // TODO code application logic here
        DataModel model =
                new FileDataModel (new File("intro.csv"));
        UserSimilarity similarity =
                new PearsonCorrelationSimilarity (model);
        UserNeighborhood neighborhood =
                new NearestNUserNeighborhood (2, similarity, model);
        Recommender recommender = new GenericUserBasedRecommender (
                model, neighborhood, similarity);
        List<RecommendedItem> recommendations =
                recommender.recommend(1, 1);
        for (RecommendedItem recommendation : recommendations) {
            System.out.println(recommendation);
        }
    }
}

but I get this error

Exception in thread "main" java.lang.NoClassDefFoundError: org/slf4j/LoggerFactory
    at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<clinit>(FileDataModel.java:119)
    at recommenderintro.RecommenderIntro.main(RecommenderIntro.java:28)
Caused by: java.lang.ClassNotFoundException: org.slf4j.LoggerFactory
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    ... 2 more
Java Result: 1

what is the problem with this code? I copied it from a book!

But using all those jar files I get the following error:

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/home/omid/Desktop/slf4j-1.7.2/slf4j-jcl-1.7.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/omid/Desktop/slf4j-1.7.2/slf4j-jdk14-1.7.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/omid/Desktop/slf4j-1.7.2/slf4j-log4j12-1.7.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/omid/Desktop/slf4j-1.7.2/slf4j-nop-1.7.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/home/omid/Desktop/slf4j-1.7.2/slf4j-simple-1.7.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Detected both jcl-over-slf4j.jar AND slf4j-jcl.jar on the class path, preempting StackOverflowError. 
SLF4J: See also http://www.slf4j.org/codes.html#jclDelegationLoop for more details.
Exception in thread "main" java.lang.ExceptionInInitializerError
    at org.slf4j.impl.StaticLoggerBinder.<init>(StaticLoggerBinder.java:73)
    at org.slf4j.impl.StaticLoggerBinder.<clinit>(StaticLoggerBinder.java:42)
    at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
    at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:107)
    at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:295)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:269)
    at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:281)
    at org.apache.mahout.cf.taste.impl.model.file.FileDataModel.<clinit>(FileDataModel.java:119)
    at recommenderintro.RecommenderIntro.main(RecommenderIntro.java:28)
Caused by: java.lang.IllegalStateException: Detected both jcl-over-slf4j.jar AND slf4j-jcl.jar on the class path, preempting StackOverflowError. See also http://www.slf4j.org/codes.html#jclDelegationLoop for more details.
    at org.slf4j.impl.JCLLoggerFactory.<clinit>(JCLLoggerFactory.java:55)
    ... 9 more
Java Result: 1

am I using extra jar files?

Upvotes: 2

Views: 3256

Answers (3)

orezvani
orezvani

Reputation: 3775

Thank you all guys.

After so much confusion on this problem, I finally solved the problem! I just web to the mahout directory and added all the jar files of "mahout/utils/target/dependency/" to the classpath.

Since I had used maven to install mahout, I could also use jar files in ".m2/" folder for the dependencies but the first solution was much simpler.

Upvotes: 0

Alex Ott
Alex Ott

Reputation: 87119

Please, take source code, or at least, pom.xml from the repository with source code for examples. This pom.xml specifies all dependencies, and everything was tested for work with different Mahout's versions. Please, look to this blog post on how to start to work with examples.

Upvotes: 2

Santosh Gokak
Santosh Gokak

Reputation: 3411

You would require the jars from the slf4j project in your classpath.

Download it from : http://www.slf4j.org/download.html

Upvotes: 3

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