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Trouble Adding .jar to classpath

Discussion in 'Java' started by zhacker, Feb 1, 2012.

  1. zhacker

    zhacker New Member

    Feb 1, 2012
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    Hi everyone,

    I have been programming in java for a while but I haven't used external .jar archives previously. Now, I am faced with the current situation:

    1- I have a java file (SNPHarvester.java) located in my /home directory.
    2- Under: /home/lib/ I have two .jar archives, namely: commons-math-1.2.jar and weka.jar
    3- In the sourcecode (SNPHarvester.java), I have the following import statements:

    import weka.core.Utils;

    import org.apache.commons.math.distribution.ChiSquaredDistribution;
    import org.apache.commons.math.distribution.ChiSquaredDistributionImpl;


    my weka.jar has the structure: weka/core/Utils.class
    my commons-math-1.2.jar contains the structure: /org/apache/commons/math/distribution/ChiSquaredDistribution.class and ChiSquaredDistributionImpl.class - However, notice the name of the .jar archive - unlike my weka.jar, commons-math-1.2 does not show up in the import statement.

    Now, when I compile using the following:

    javac -cp ".:lib/weka.jar:lib/commons-math-1.2.jar" SNPHarvester.java it outputs the following:

    [zibrahimbrc@bignode lib]$ javac -cp ".:lib/weka.jar:lib/commons-math-1.2.jar" SNPHarvester.java
    javac: file not found: SNPHarvester.java
    Usage: javac <options> <source files>
    use -help for a list of possible options

    Which I am assuming it's okay. However, the following exception is generated when I run the corresponding .class file:

    [zibrahimbrc@bignode snp_harvester]$ java SNPHarvester
    Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/math/distribution/ChiSquaredDistribution
    Caused by: java.lang.ClassNotFoundException: org.apache.commons.math.distribution.ChiSquaredDistribution
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
    Could not find the main class: SNPHarvester. Program will exit.

    It's not finding the classes in commons-math-1.2.jar

    Any ideas about what I'm doing wrong? your help is highly appreciated. Thank you very much in advance.

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